TSUNAMIS IN JAPAN
Japan gave the world the word tsunami.More than 800 tsunamis have been generated in the Pacific in the last century. Some 22 percent of these were generated off of Japan According to geological evidence catastrophic tsunamis like the one that hit Sumatra, Thailand and Sri Lanka in 2004, strike Japan every 400 or 500 years.
There are worries that a large tsunami on the Pacific coast could kill tens of thousands of people and cause hundreds of billions of dollars in damage. A large earthquake off the east coast of Japan could produce a huge tsunami and people would only have minutes to evacuate even if they are given a warning when the earthquake occurs.
Geologists looking for evidence of past tsunamis examine exposed dirt and rock along river banks, road cuts and cliffs or simply dig into the ground or take core samples to check whether layers of sediment contain any materials deposited by tsunami. A tsunami carries sand, shells and even large stones inland from the sea, depositing them on the ground as it recedes. Layers discovered today are viewed as evidence of past tsunamis. The height of tsunami sediments is an indicator of the height of a tsunami.
damage from 1983 tsunami
History of Large Tsunamis in Japan
A tsunami in 1618 leveled much of the area around Sendai leveled by the 2011 one. On January 27, 1700, a large tsunami hit a 1,000 kilometer section of Japan’s Pacific coast. It crested at five meters and washed hundred of meters inland and washed up rivers more than two kilometers. The tsunami was generated by a massive earthquake off the American Pacific Northwest coast.
The highest recorded tsunami caused by an offshore earthquake occurred off Ishigaki Island in the Ryukyu chain on April 24, 1771. According to the Guinness Book of Records. it tossed an 830-ton block of coral more than 1½ miles inland and may have been as high as 279 feet.
Unzen, a large volcano on Kyushu near Nagasakai, erupted catastrophically in 1792. An earthquake triggered by the eruption and the collapse of a lava dome sent an entire mountain side sliding into the ocean. The ensuing 100-meter-high tsunami submerged coastal villages, killing about 15,000 people. Tsunamis engulfed the city of Shimabara with water reaching as far inland as the gates of the city castle. More than 43 square miles of the Shimabara peninsula was covered by water. The waves then traveled across the bay, washing away nearly 6,000 houses and 1,600 fishing boats along another 75-miles section of coastline.
An 8.2 earthquake in Hokaido in 1952 and an 8 earthquake in 1843 caused tsunamis between four and seven meters (See Tsunamis).
Occurrences of Major Pacific Tsunamis More Frequent Than Previously Thought
November 2011, Kyodo reported: “The probability of a major earthquake occurring and triggering a massive tsunami in the Pacific Ocean off eastern and northeastern Japan within the next 30 years has been revised up to 30 percent from 20 percent, a government panel said. [Source: Kyodo, November 26, 2011]
The Earthquake Research Committee has reexamined its long-term estimate of killer temblors after the March 11 quake and tsunami and found that a quake that triggers a tsunami as powerful as the one caused by the 1896 Meiji-Sanriku Earthquake, which killed more than 20,000 people, is more likely to happen in the sea zone stretching 800 kilometers north-south.
The panel stopped short of predicting the magnitude of the possible quake but said past records suggest it would be magnitude 8 or stronger. The tsunami triggered by the 1896 quake reached as high as 38.2 meters, according to the records. The quake's estimated magnitude ranges from 6.8 to 8.5 among experts. Meanwhile, the committee said the likelihood a quake with a magnitude of up to 9 occurs within the next 50 years in a sea area off Miyagi and Fukushima prefectures, which is closer to the shore than the 800-km zone, is almost zero percent.
The Yomiuri Shimbun reported that according to the same report major ocean trench earthquakes have occurred off the Pacific coast from the Sanriku to Boso regions once every 600 years, according to a government panel report, meaning the frequency of temblors like the Great East Japan Earthquake of March 2011 is much greater than the previously estimated 1,000 years. [Source: Yomiuri Shimbun, November 25, 2011]
The March 11 quake is believed to have been about the same strength as the Jogan Earthquake of 869, which led some experts to suggest such quakes occur about once every 1,000 years. However, the panel discovered such quakes have occurred with greater frequency, according to detailed research of substances moved by tsunami over thousands of years. Before the March 11 disaster, predictions of the frequency of Sanriku-Boso offshore earthquakes had been based on historical records of earthquakes that struck over the past 400 years, including frequent quakes off Miyagi Prefecture.The March 11 disaster, however, was beyond those predictions because it involved several separate, almost simultaneous earthquakes that affected a large area.
The report was drawn up by the Earthquake Research Committee, which has been reviewing long-term probability assessments about major earthquakes. The report reflected examination of substances deposited in geological layers by tsunami over the last 2,500 years. The report concluded that multiple-quake events with subsequent large-scale tsunami have occurred five times: in about the fourth or third century B.C.; in about the fourth or fifth century; in 869; in about the 15th century; and on March 11. The report also predicts the size of the next such quake will be of magnitude 8.3 to 9. The report said that because crustal movement caused by the March 11 quake is still continuing, probability assessments should be reassessed in the future and monitoring of conditions in the region should be increased.
Coral from Tsunami the in Okinawa Area in 1771
Ishigakijima and neighboring areas in Okinawa Prefecture were struck by waves more than 30 meters high during the Meiwa tsunami in 1771. About 12,000 people are believed to have been killed or gone missing in the disaster. [Source: Yomiuri Shimbun, June 23, 2011]
Daisuke Araoka, a 25-year-old graduate student at the University of Tokyo, has found a way to date this and other tsunamis by analyzing fossilized coral. The standard dating method for tsunami is to examine materials deposited on land by the waves. However, Araoka has discovered through his research of dead porites coral that there is a strong possibility large tsunami have occurred every 150 to 400 years in the Sakishima islands in Okinawa Prefecture, including Ishigakijima island.
Porites coral usually grows in boulder-shaped masses in the sea. It dies after being washed ashore, and fossilized porites coral can been seen on a wide stretch of beaches on the Sakishima islands. Fossilized porites coral one to nine meters in diameter is believed to have been washed ashore by large waves, including tsunami. A scholar of the natural environment, Araoka calculated the time of such coral's death through radiocarbon dating, and uranium and thorium dating. He then checked whether the timing coincided with tsunami on the Sakishima islands.
Araoka found many coral that appeared to have died before or after 1771, as well as coral deaths that coincided with a 1625 tsunami. He therefore concluded it was possible to precisely date tsunami through fossilized porites coral. Araoka's investigations also turned up evidence to corroborate the legend of a particularly high tide on Miyakojima island around 1460, of which there is no documentary record, and of the legend of a big wave hitting Tarama Island around 1200. Moreover, by researching the death of coral for more than 2,000 years back, Araoka found tsunami were likely to have occurred every 150 to 400 years on the Sakishima islands.
Jogan Earthquake and Tsunami
There was a great tsunami in A.D. 869. Generated by a quake known as Jogan, it struck the Sendai area and produced tsunami waves that reached almost two kilometers inland in an area just north of the present-day Fukushima nuclear power plant. According to Japan's historical document, "Nihon Sandai Jitsuroku" ("The True History of Three Reigns of Japan"), compiled during the early Heian Period (794-1192), the Jogan Tsunami flooded inland areas more than three kilometers from shore and killed more than 1,000 people.
The 869 Jogan earthquake (also known as the Sanriku earthquake or Jo-gan jishin) and associated tsunami struck the area around Sendai in the northern part of Honshu on July 9, 869 (26th day of 5th month, 11th year of Jo-gan). The earthquake had an estimated magnitude of 8.6 on the surface wave magnitude scale. However, it is likely that the moment magnitude rating may have been similar to the 2011 To-hoku earthquake and tsunami at around 9.0. [Source: Wikipedia +]
According to the Active Fault and Earthquake Research Center the quake that caused the Jogan Tsunami made the fault slip more than seven meters. According to a report submitted by the national institute to the government in the spring of 2010, the Jogan Earthquake occurred off Miyagi and Fukushima prefectures and is estimated to have had a magnitude of about 8.3 or 8.4. The Jogan Earthquake tsunami penetrated more than four kilometers inland in the Sendai plain in Miyagi Prefecture, and about 1.5 kilometers inland in an area where Minami-Soma, Fukushima Prefecture, is currently located, the report said. According to a study conducted by Tohoku University, two tsunamis equivalent to the size of the Jogan Earthquake tsunami have hit the Sendai plain in the past 3,000 years. [Source: Yomiuri Shimbun, June 12, 2011 ^^]
A passage in the “Nihon Sandai Jitsuroku” read: “The lands of Mutsunokuni were severely jolted. The sea covered dozens, hundreds of blocks of land. About 1,000 people drowned...The sea soon rushed into the villages and towns, overwhelming a few hundred miles of land along the coast. There was scarcely any time for escape, though there were boats and the high ground just before them. In this way about 1,000 people were killed.” Mutsunokuni is the name of the region that covered most of the present-day prefectures in the Tohoku region. ^^
According to the "Nihon Sandai Jitsuroku:" On 26th day of 5th month (9 July 869 AD) a large earthquake occurred in Mutsu province with some strange light in the sky. People shouted and cried, lay down and could not stand up. Some were killed by the collapsed houses, others by the landslides. Cattle got surprised, madly rushed around and injured the others. Enormous buildings, warehouses, gates and walls were destroyed. Then the sea began roaring like a big thunderstorm. The sea surface suddenly rose up and the huge waves attacked the land. They raged like nightmares, and immediately reached the city center. The waves spread thousands of yards from the beach, and we could not see how large the devastated area was. The fields and roads completely sank into the sea. About one thousand people drowned in the waves, because they failed to escape either offshore or uphill from the waves. The properties and crop seedlings were almost completely washed away. +
In Japan this earthquake is commonly called "Jogan Jishin". Jo-gan is the Japanese era name for the period from 859 to 877 AD. But during the era other large earthquakes also occurred in Japan, so the name of the geographic epicenter and the anno domini year number when the quake occurred are sometimes added. Sanriku in this context is a name roughly corresponding to the Pacific front northeastern coastal area of Honshu island. The Japanese history text, Nihon Sandai Jitsuroku which was compiled in 901, recorded the 869 earthquake and tsunami of Mutsu Province. + Although this earthquake occurred in the frontier region of the ancient Japanese Empire based at Kyoto, a short but surprisingly precise official record of this catastrophe was left. +
In the area which the earthquake struck, the Imperial Court of Japan battled with an indigenous people of the To-hoku region, Emishi, at that time. According to Nihon Sandai Jitsuroku, around 1000 people were killed by the tsunami.Despite a lack of reliable sources, there are legends about the earthquake from To-hoku region to Bo-so- Peninsula. The tsunami caused extensive flooding of the Sendai plain, destroying the town of Tagajo-. Archaeological investigations have identified the remains of 8th and 9th century buildings beneath the town, covered by sediments dated to the middle of the 10th century. +
Since 1990, Tohoku Electric Power Co., Tohoku University and the National Institute of Advanced Industrial Science and Technology have researched the traces left by the Jogan Earthquake. Their studies have shown that the ancient tsunami was on the same scale as that caused by the March 11 earthquake. The tsunami from Jogan earthquake left sand deposits miles inland. Based on sediments found in coastal areas from Miyagi Prefecture to Fukushima Prefecture thought to have been carried there by tsunami caused by the Jogan Earthquake, scientists estimated that the Jogan Earthquake had a magnitude of more than 8. ^^
Geology of the 869 Sanriku Earthquake and Tsunami
The northern part of Honshu lies above the convergent boundary between the over-riding Okhotsk Plate (a proposed microplate within the North American Plate) and the subducting Pacific Plate. This boundary has been associated with a series of large historical earthquakes, originating either from rupture along the plate interface or from deformation within either the over-riding or subducting plates, many of them triggering a destructive tsunami, such as the 1896 Meiji-Sanriku earthquake. [Source: Wikipedia +]
The estimated magnitude of the earthquake as 8.6 on the surface wave magnitude scale, has been taken from modelling of the tsunami. A source area of 200 kilometers (120 miles) long by 85 kilometers (53 miles) wide with a displacement of 2 metres (6 feet 7 in) is consistent with the observed distribution and degree of flooding. Analysis of the tsunami deposits associated with the 2011 earthquake suggests that the extent of sand deposition in the earlier events underestimated the degree of inundation. A muddy deposit was found to extend half as far again as the sand sheet. As the topography and cultivation of the Sendai plain has not changed significantly since 869, it has been proposed that the sources of the 2011 and 869 tsunamis were of comparable size, suggesting that the magnitude of the 869 earthquake has been severely underestimated. Thus the magnitude of this quake may have been as high as 9.0. +
The extent of flooding caused by the tsunami of the Sendai plain has been mapped using dated deposits of sand. The tsunami flooded at least 4 kilometers (2.5 miles) inland. The inundated areas closely matched those of the 2011 To-hoku tsunami. Three tsunami deposits have been identified within the Holocene sequence of the Sendai plain, all formed within the last 3,000 years, suggesting an 800 to 1,100 year recurrence interval for large tsunamigenic earthquakes. In 2001 it was reckoned that there was a high likelihood of a large tsunami hitting the Sendai plain as more than 1,100 years had then elapsed. +
As for the other two large tsunamis recognized before the 869 tsunami, one was estimated to have occurred between about 1000 B.C. and 500 B.C. and the other around A.D. 1. In 2007 the probability of an earthquake with a magnitude of Mw 8.1–8.3 was estimated as 99 percent within the following 30 years. The 2011 To-hoku earthquake was somewhat larger than the predicted event, but occurred in the same area as the 869 earthquake and caused major flooding in the Sendai area. +
Kamaishi Bay, 1933 Tsunami
The Sanriku coastal region of Tohoku (northern Honshu) has a history of being struck by strong tsunamis. Tsunamis in 1896 and 1933 that struck the northeast coast of Japan around Sanriku killed thousands of people. The one on June 15, 1896 killed 27,120 people in Iwate Prefecture and other areas and occurred after a large earthquake at sea. Fishermen who had been out at sea didn’t even notice the tsunami when it slipped under their boats. When they returned home they found their villages destroyed and their family members dead or disappeared. There was little warning. The other one was produced by the Sanriku Offshore Earthquake on March 3, 1933, which measured 8.1 on the Richter scale. Most of the 3,008 dead and many of the 7,479 injured were victims of the tsunami.
The 1896 Sanriku earthquake produced tsunami waves that were just as large and catastrophic as the 9.0 earthquake in 2011. Researchers have estimated that the largest-known tsunami wave to strike Japan was 38.2 meters high and came ashore in Ofunato in Iwate Prefecture in 1896. In the 1896 Sanriku earthquake when many died because they were trying to help family members when the tsunami struck. In the Taro district of Miyako, Iwate Prefecture only 36 of the town’s 1,859 residents survived,
The 1933 Showa Sanriku quake, which triggered a tsunami that left more than 900 people dead or missing in the Taro district of Miyako, Iwate. The Great Chilean Earthquake in 1960 that killed 142 people in Japan.
In 1993 a magnitude 7.8 quake produced tsunamis with heights greater than 30 feet off Japan’s western coast, spreading wide devastation. On the hard-hit island of Okushiri, “most of the populated areas worst hit by the tsunami were bounded by tsunami walls” Japanese scientists reported. According to the report the walls “may have moderated the overall tsunami effects but were ineffective for higher waves.”
Massive Sanriku Tsunami Hit Six Times in 6,000 Years'
Sediments indicating that massive tsunamis of 10 or more meters in height hit the Sanriku coast six times during the past 6,000 years have been found in strata of a cliff in Kesennuma, Miyagi Prefecture, the Yomiuri Shimbun reported. The discovery was made by a team led by Kazuomi Hirakawa, a special appointment professor at Hokkaido University and an expert in geomorphology, at Oya beach in the city. [Source: Yomiuri Shimbun, August 25, 2011]
Hirakawa said the traces suggest the region has been hit every 1,000 years or so by an earthquake with a magnitude of about 9, similar to the Great East Japan Earthquake. As the cliff is located about three meters above sea level, no sediment should have been left by tsunami only a few meters high, according to Hirakawa.
The research team found six layers of sediment. Based on clues such as volcanic ash known to date from about 5,400 years ago, the team estimated the time each layer was created. According to their estimate, the sediment they found in the oldest layer is believed to have been brought by tsunami that hit the area about 5,500 to 6,000 years ago. The sediment deposits in the remaining layers are believed to have been brought by ancient tsunami about 4,000 years ago, about 3,000 years ago and about 2,000 years ago, followed by tsunami caused by the Jogan earthquake in 869 and the Keicho earthquake in 1611.
1611 Sanriku Earthquake and Tsunami
The 1611 Sanriku earthquake (Keicho- Sanriku Jishin) occurred at about 10:30am on December 2, 1611 with an epicenter off the Sanriku coast in Iwate Prefecture. The magnitude of the earthquake was 8.1M It triggered a devastating tsunami. A description of this event in an official diary from 1612 is probably the first recorded use of the term 'tsunami'. According to old documents, the earth shook violently three times. The first waves of the devastating tsunami struck at about 2:00pm—3½ hours after the initial earthquake. There were about 5,000 casualties. [Source: Wikipedia +]
The estimated rupture area for the earthquake is similar to that calculated for the 1933 Sanriku earthquake. With this earthquake, the area along the Pacific Ocean in what is currently called the Sanriku Coast did shake strongly, but only about 4-5 on the Shindo scale. The damage from the tsunami far exceeded that from the earthquake, so this is considered to be a tsunami earthquake. Consequently, the disaster caused by earthquake is also known as the "Keicho Sanriku tsunami earthquake". It would have been very similar to the 1605 Keicho- Nankaido- earthquake, a tsunami earthquake in the Nankai Trough area. +
The source of the earthquake was off the north coast of Sanriku. However, due to the time delay of nearly four hours before the tsunami arrived, there are questions about the exact location of the source. Professor Kazuomi Hirakawa of Hokkaido University has found tsunami deposits on the southern part of Hokkaido and northern Sanriku from the early part of the 17th century. It is possible that the earthquake and tsunami in Sanriku was an enormous quake that resonated even in the area of the Kurile Trench off the eastern coast of Hokkaido. +
The tsunami reached its maximum estimated height of about 20 meters at O-funato, Iwate. The tsunami struck on the east coast of Sanriku from Sendai bay in the south to southeastern Hokkaido in the north, a greater length of coastline than was affected by the 1896 tsunami. According to old documents, 1,783 people were killed in the Sendai Domain, and over 3000 horses and men in the Nanbu and Tsugaru domains. On the southern coast of Hokkaido, many Ainu were also drowned ("Hokkaido History"). Amongst the worst affected places was O-tsuchi, with 800 deaths. +
1896 Sanriku Earthquake and Tsunami
On June 15, 1896, nearly 22,000 Japanese lost their lives due to one of the most devastating tsunamis in Japanese history. Striking the same region as the March 2011 earthquake and tsunami, the The earthquake occurred on the evening of the Boy's Festival Day (Tango-no-sekku) on the lunar calendar, and many people had gathered indoors for the parties. This delayed evacuation and is the reason cited for the drowning deaths of thousands. The tsunami, which was generated by the earthquake off the coast of Sanriku, Japan, attained a height of 25 meters and instantly swept away all houses and people when it reached land. [Source: History of Tsunamis in Japan, .stfrancis.edu *+*]
One hundred years after this earthquake, two researchers became determined to figure out its source. Yuichiro Tanioka of the Department of Geological Science of the University of Michigan, and Ann Arbor and Kenji Satake of the Seismotectonics Section of the Geological Survey of Japan, Tsukuba, developed a model using a modern computer simulation. The results of their research indicate that the source of the earthquake was very close to the Japan trench. They estimated that the fault that generated the earthquake had a width of 50 kilometers, and the movement along the fault was 5.7 meters. The earthquake ruptured beneath an accretionary wedge, a relatively shallow area. If a substantial occurs in the same area in the future, a resulting tsunami could be unusually large, like the 1896 event. *+*
The 8.5 magnitude earthquake occurred at 19:32 (local time) on June 15, 1896, approximately 166 kilometers (103 miles) off the coast of Iwate Prefecture, Honshu. It resulted in two tsunamis which destroyed about 9,000 homes and caused at least 22,000 deaths. The waves reached a record height of 38.2 metres (125 feet); more than a meter shorter than those created after the 2011 Tohoku earthquake which triggered the 2011 Japanese nuclear accidents. Seismologists have discovered the tsunamis' magnitude (Mt = 8.2) was much greater than expected for the estimated seismic magnitude. This earthquake is now regarded as being part of a distinct class of seismic events, the tsunami earthquake. By some counts the number of casualties was 22,066. [Source: Wikipedia +]
The unusual disparity between the magnitude of the earthquake and the subsequent tsunami may be due to a combination of forces: 1) the tsunami was caused by a slope failure triggered by the earthquake; and 2) the rupture velocity was unusually low Scientists believe the effect of subducted sediment beneath the accretionary wedge was responsible for a slow rupture velocity. The effects of a 20̊ dipping fault along the top of the subducting plate was found to match both the observed seismic response and tsunami, but required a displacement of 10.4 meters. The displacement was reduced to a more reasonable value after the extra uplift caused by the deformation of sediments in the wedge and a shallower fault dip of 10̊ was considered. This revised fault model gave a magnitude of Mw=8.0-8.1. A figure much closer to the estimated actual tsunami magnitude. A magnitude of 8.5 on the moment magnitude scale has also been estimated for this event. +
On the evening of June 15, 1896, communities along the Sanriku coast in northern Japan were celebrating a Shinto holiday and the return of soldiers from the First Sino-Japanese War. After a small earthquake, there was little concern because it was so weak and many small tremors had also been felt in previous few months. However 35 minutes later the first tsunami wave struck the coast followed by a second a few minutes later. Damage was particularly severe because the tsunamis had coincided with high tides. Most deaths occurred in Iwate and Miyagi although casualties were also recorded from Aomori and Hokkaido. +
The power of the tsunami was great and large numbers of victims were found with broken bodies or missing limbs. As was their normal practice each evening, the local fishing fleets were all at sea when the tsunamis struck. In the deep water the wave went unnoticed. Only when they returned the next morning did they discover the debris and bodies. Wave heights of up to 9 meters (30 feet) were also measured in Hawaii. They destroyed wharves and swept several houses away. +
Preventative coastal measures were not implemented until after another tsunami struck in 1933. Due to higher levels of tsunami awareness, fewer casualties were recorded following the Sanriku earthquake. Nevertheless the earthquake of 11 March 2011 caused a huge tsunami that resulted in thousands of deaths across the same region and a nuclear disaster.
1933 Sanriku Earthquake and Tsunami
The 1933 Sanriku earthquake (Sho-wa Sanriku Jishin) was a major earthquake whose associated tsunami caused widespread damage to towns on the Sanriku coast of the Tohoku region of Honshu, Japan on March 2, 1933. The epicenter of the 1933 Sanriku earthquake was located offshore, 290 kilometers (180 miles) east of the city of Kamaishi, Iwate. The initial shock occurred at 2:31am local time on March 3, 1933. Over 3,000 people were killed, mostly by the tsunami. [Source: Wikipedia +]
The earthquake measured 8.4 on the moment magnitude scale and was in approximately the same location as the 1896 Meiji-Sanriku earthquake. The epicenter occurred far enough away from the town that the earthquake itself did little damage to buildings. Approximately three hours after the main shock was a magnitude 6.8 aftershock, followed by 76 more aftershocks (with a magnitude of 5.0 or greater) over a period of six months. This earthquake was an intraplate earthquake in the Pacific Plate. The focal mechanism of this earthquake showed that it was a normal faulting earthquake. +
Although the earthquake did little damage, the associated tsunami, which was recorded to reach the height of 28.7 metres (94 feet) at O-funato, Iwate, caused extensive damage, destroyed many homes and caused numerous casualties The tsunami destroyed over 7,000 homes along the northern Japanese coastline, of which over 4,885 were washed away. The tsunami was also recorded in Hawaii with a height of 9.5 feet (2.9 meters), and which also resulted in slight damage. The death toll came to 1522 people confirmed dead, 1542 missing, and 12,053 injured. Hardest hit was the town of Taro-, Iwate (now part of Miyako city), with 98 percent of its houses destroyed and 42 percent of its population killed. +
Tokai, Tonankai and Nankai Triple Megaquakes and Tsunamis
The magnitude-8.6 Hoei earthquake of 1707 was the most powerful earthquake involving simultaneous ruptures this country has ever seen. The enormous quake involved Tokai, Tonankai and Nankai temblors occurring simultaneously. This megaquake and the ensuing tsunami killed more than 20,000 people and destroyed at least 80,000 houses.
"Earthquakes in 887 and 1361 must have involved simultaneous ruptures in all three zones [Tokai, Tonankai and Nankai],"said Yoshinobu Tsuji, associate professor at the Earthquake Research Institute of the University of Tokyo.
Tsuji has studied ancient documents at Horyuji temple in Nara Prefecture that describe a tsunami that hit Osaka after the Shohei Nankai earthquake in 1361. The writings say the tsunami reached about one kilometer farther inland than the wave following the Hoei quake. A text from the Heian period (794-1192)--"Nihon Sandai Jitsuroku" (The True History of Three Reigns of Japan)--describes enormous tsunami damage to Osaka after the Ninna Goki Shichido earthquake in 887.
"It's already been more than 300 years since the Hoei earthquake. Judging from the frequency that's been recorded, there's about a 30 percent chance of a major earthquake occurring soon in this region--one where a rupture in one zone happens at the same time as quakes in the other two," Tsuji said, also saying detailed preparations needed to be made.
Meanwhile, the Keicho earthquake that occurred in 1605 did not involve strong earth movements, but the subsequent tsunami caused extensive damage from the Kanto region to Shikoku. This earthquake occurred at a shallow point under the seabed near the Nankai Trough, which triggered a major tsunami via a mechanism different to those caused by the simultaneous ruptures described above.
1498 Nankai Earthquake and Tsunami
The 1498 Nankai earthquake (Meio- Jishin) occurred off the coast of Nankaido, Japan, at about 8:00am local time on September 20, 1498. It had a magnitude estimated at 8.6 and triggered a large tsunami. The death toll associated with this event is uncertain, but between 26,000 and 31,000 casualties were reported. [Source: Wikipedia +]
The southern coast of Honshu- runs parallel to the Nankai Trough, which marks the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Movement on this convergent plate boundary leads to many earthquakes, some of them of megathrust type. The Nankai megathrust has five distinct segments (A-E) that can rupture independently, the segments have ruptured either singly or together repeatedly over the last 1,300 years. Megathrust earthquakes on this structure tend to occur in pairs, with a relatively short time gap between them. In addition to the two events in 1854, there were similar earthquakes in 1944 and 1946. In each case, the northeastern segment ruptured before the southwestern segment. In the 1498 event, the earthquake is thought to have ruptured segments C, D and E and possibly A and B. If both parts of the megathrust ruptured, the events were either simultaneous, or close enough in time, to not be distinguished by historical sources. +
Severe shaking caused by this earthquake was recorded from Bo-so- Peninsula in the northeast to Kii Peninsula in the southwest. A tsunami was recorded in Suruga Bay and at Kamakura, where it destroyed the building housing the statue of the Great Buddha at Ko-toku-in. There is also evidence of severe shaking from records of ground liquefaction in the Nankai area. Tsunami deposits attributed to this earthquake have been described from the coastal plains around the Sagami Trough and the Izu Peninsula. Uplift of the seafloor of up to 4 meters has been estimated for this earthquake, with a much smaller subsidence near the coast. Lake Hamana became a brackish lake because the tsunami broke shoal between the lake and the Pacific Ocean (Enshu- Nada). +
1605 Nankai Earthquake and Tsunami
The 1605 Nankai earthquake occurred at about 20:00 local time on February 3. It had an estimated magnitude of 7.9 on the surface wave magnitude scale and triggered a devastating tsunami that resulted in thousands of deaths in the Nankai and Tokai regions of Japan. It is uncertain whether there were two separate earthquakes separated by a short time interval or a single event. It is referred to as a tsunami earthquake, in that the size of the tsunami greatly exceeds that expected from the magnitude of the earthquake. [Source: Wikipedia +]
The southern coast of Honshu runs parallel to the Nankai Trough, which marks the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Movement on this convergent plate boundary leads to many earthquakes, some of them of megathrust type. The Nankai megathrust has five distinct segments (A-E) that can rupture independently, the segments have ruptured either singly or together repeatedly over the last 1,300 years. Megathrust earthquakes on this structure tend to occur in pairs, with a relatively short time gap between them although in the 1707 Ho-ei earthquake all segments are thought to have ruptured at once. In 1854 there were two earthquakes a day apart and there were similar earthquakes in 1944 and 1946. In each case, the northeastern segment ruptured before the southwestern segment. In the 1605 event, there is evidence for two distinct earthquakes, but they are not distinguished by all historical sources and some seismologists suggest that only the Nankai segment of the megathrust ruptured. +
There are very few reports of shaking associated with this earthquake, with most historical records only mentioning the tsunami. This has led seismologists to interpret this as a 'tsunami earthquake', probably involving a slow rupture velocity causing little observed shaking while generating a large tsunami.
The records of this tsunami are quite sparse but the maximum wave heights are larger than those for either the 1707 Ho-ei or 1854 Ansei Nankai tsunamis in areas on the south coast of Shikoku where they can be compared. The regional extent of this tsunami is supported by the discovery of tsunami deposits on the northeastern part of the Kii Peninsula and at Lake Hamana correlated to this event. Victims of the tsunami were also reported from Kyushu.
There is no reported damage associated with the earthquake itself. At least 700 houses were washed away at Hiro in present-day Wakayama prefecture and 80 at Arai in what is now Shizuoka prefecture. Castles were reported destroyed or damaged at Tahara on the Atsumi Peninsula; the main keep of Kakegawa Castle was also destroyed. The total number of casualties is uncertain as records are incomplete and contradictory, but estimates are in the order of thousands.
1854 Tokai Earthquake and Tsunami
The 1854 Tokai earthquake was the first of the Ansei Great Earthquakes (1854–1855). It occurred at about 9:00am local time on December 23, 1854. It had a magnitude of 8.4 and caused a damaging tsunami. More than 10,000 buildings were completely destroyed and there were at least 2,000 casualties. It was the first of the three Ansei Great Earthquakes; the 1854 Ansei-Nankai earthquake of similar size hit southern Honshu the following day. [Source: Wikipedia +]
The southern coast of Honshu runs parallel to the Nankai Trough, which marks the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Movement on this convergent plate boundary leads to many earthquakes, some of them of megathrust type. The Nankai megathrust has five distinct segments (A-E) that can rupture independently, the segments have ruptured either singly or together repeatedly over the last 1300 years. Megathrust earthquakes on this structure tend to occur in pairs, with a relatively short time gap between them. In addition to the two events in 1854, there were similar earthquakes in 1944 and 1946. In each case the northeastern segment ruptured before the southwestern segment. +
Much of central Japan experienced seismic intensities of 5 (on the JMA scale). Damage from this earthquake was particularly severe in the coastal areas of Shizuoka Prefecture from Numazu to Tenryu River, with many houses being damaged or destroyed. +
On the east side of the Izu Peninsula, Shimoda was hit by the tsunami one hour after the earthquake. A series of nine waves struck the city, destroying 840 houses and claiming 122 lives. Diana, the flagship of a visiting Russian admiral, Putyatin, was spun round 42 times on its moorings and was so badly damaged that it sank in a later storm. At Suruga Bay, on the west side of the Izu Peninsula, the village of Iruma was completely destroyed and a 10 meters high sand dome was deposited, on which the village was later reconstructed. +
In most of the affected areas, run-up heights were in the range of 4–6 meters. At Iruma, run-up heights of 13.2 and 16.5 meters have been measured, much higher than most of the surrounding area. This and the deposition of the unusual sand dome, with an estimated volume of 700,000 m3, is interpreted to have been caused by the effects of resonance in the V-shaped Iruma bay.
1854 Nankai Earthquake and Tsunami
The 1854 Nankai earthquake occurred at about 4:00pm local time on December 24, 1854. It had a magnitude of 8.4 and caused a damaging tsunami. More than 30,000 buildings were completely destroyed and there were at least 3,000 casualties. It was the second of the three Ansei Great Earthquakes; the 1854 Ansei-To-kai earthquake of similar size had hit the area the previous morning. [Source: Wikipedia +]
The southern coast of Honshu runs parallel to the Nankai Trough, which marks the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Movement on this convergent plate boundary leads to many earthquakes, some of them of megathrust type. The Nankai megathrust has five distinct segments (A-E) that can rupture independently, the segments have ruptured either singly or together repeatedly over the last 1300 years. Megathrust earthquakes on this structure tend to occur in pairs, with a relatively short time gap between them. In addition to the two events in 1854, there were similar earthquakes in 1944 and 1946. In each case the northeastern segment ruptured before the southwestern segment. +
The damage due to the earthquake was severe with 5,000 houses being destroyed and 40,000 houses badly damaged. A further 6,000 homes were damaged by fire. The tsunami washed away a further 15,000 houses and a total of 3,000 people died from either the earthquake or the tsunami. The death toll associated with the tsunami was less than would be expected in comparison to the 1707 tsunami, because many people had left the coastal area following the large earthquake the previous day. In Hiro (now Hirogawa), Goryo Hamaguchi set fires using rice straw to help guide villagers to safety. This story was turned into "A living god" by the Greek-born writer Lafcadio Hearn.
Much of southwestern Honshu, Shikoku and Kyu-shu- experienced shaking of 5 or more on the JMA scale, with most of Shikoku and nearby coastal areas of Kansai suffering an intensity of 6. On Shikoku, the greatest inundation heights were 7.5 meters in Mugi, 7.5 meters in Kamikawaguchi of Kuroshio, 7.2 meters at Asakawa on the Tokushima coast, 7.4 meters at Usa, 8.4 meters at O-nogo- in the Susaki area, 8.3 meters at Kure on the Ko-chi coast and 5 meters at both Hisayoshiura and Kaizuka on the coast of Ehime.
1944 Tokai Earthquake and Tsunami
The 1944 Tokai earthquake occurred at 1:35pm local time on 7 December. It had an estimated magnitude of 8.1 on the moment magnitude scale and a maximum felt intensity of greater than 5 shindo (about VIII (destructive) on the Mercalli intensity scale). It triggered a large tsunami that caused serious damage along the coast of Wakayama Prefecture and the To-kai region. Together the earthquake and tsunami caused 1,223 casualties. [Source: Wikipedia +]
There was severe damage from the earthquake on the eastern side of the Kii Peninsula particularly in the cities of Shingu- and Tsu. A total of 26,146 houses were destroyed by the shaking, including 11 that burned down and a further 3,059 houses were destroyed by the tsunami. Nearly 47,000 houses were seriously damaged by the combined effects of the earthquake and tsunami. There were 1,223 people killed and a further 2,135 were seriously injured. +
The southern coast of Honshu- runs parallel to the Nankai Trough, which marks the subduction of the Philippine Sea Plate beneath the Eurasian Plate. Movement on this convergent plate boundary leads to many earthquakes, some of them of megathrust type. The Nankai megathrust has five distinct segments (A-E) that can rupture independently, the segments have ruptured either singly or together repeatedly over the last 1300 years. Megathrust earthquakes on this structure tend to occur in pairs, with a relatively short time gap between them. The 1944 event, which ruptured the C & D segments was followed two years late by the 1946 Nankaido- earthquake, rupturing segments A & B. In addition to these two events, there were two similar earthquakes in 1854. In each case the northeastern segment ruptured before the southwestern segment. +
Felt intensities of greater than Shindo 5 were recorded along the southern coast of Honshu-, with Shindo 3–4 in Tokyo. The observed teleseismic response and tsunami records have been matched using a rupture area of 220 x 140 kilometers and a maximum displacement of 2.3 meters. It has been suggested that splay faults, linking back into the plate interface, have had an important role in generating large tsunamigenic earthquakes along the Nankai trough. The 1944 event could have occurred on such a splay fault.
As for the tsunami the maximum recorded wave height was 10 meters on the Kumano coast. Run-ups in excess of 5 meters were also recorded at several locations along the coasts of Mie and Wakayama Prefectures. The tsunami was observed along the Pacific coast of Japan from Izu Peninsula to Kyushu, and recorded by tide gauges from Alaska to Hawaii.
1946 Nankai Earthquake and Tsunami
The Nankai Earthquake of December 21, 1946, was an interplate earthquake with a source region in an area along the Nankai Trough. The seismic ground motion from this earthquake is estimated to have corresponded to a seismic intensity of 6 in JMA scale. A tsunami generated by this earthquake caused significant damage in many areas. The tsunami height was 4 to 7 meters along the Pacific coast. It did reach as high as 11m in some places, however. This tsunami caused damage through the reversed flow in the Kizugawa River and the Ajigawa River in Osaka. There were a total of 1,443 dead or missing, 3,842 injured, and 9,000 houses completely collapsed. There were a total of forty aftershocks of magnitude 5 or larger accompanying this earthquake that lasted until April of 1947, resulting in crustal deformation of the land. [Source: History of Tsunamis in Japan, .stfrancis.edu *+*]
The 1946 Nankai earthquake occurred on 4:19am local time. It measured between 8.1 and 8.4 on the moment magnitude scale, and was felt from Northern Honshu- to Kyu-shu-. It occurred almost two years after the 1944 To-nankai earthquake, which ruptured the adjacent part of the Nankai megathrust. The 1946 Nankai earthquake occurred in the Nankai Trough, a convergent boundary where the Philippine Sea Plate is being subducted beneath the Eurasian Plate. Large earthquakes have been recorded along this zone since the 7th century, with a recurrence time of 100 to 200 years. *-*
The 1946 Nankaido earthquake was unusual in its seismological perspective, with a rupture zone estimated from long-period geodetic data that was more than twice as large as that derived from shorter period seismic data. In the center of this earthquake rupture zone, scientists used densely deployed ocean bottom seismographs to detect a subducted seamount 13 kilometers (8 miles) thick by 50 kilometers (31 miles) wide at a depth of 10 kilometers (6 miles). Scientists propose that this seamount might work as a barrier inhibiting brittle seismogenic rupture. [Source: Wikipedia +]
The earthquake caused extensive damage, eventually destroying 36,000 homes in southern Honshu- alone. The earthquake also caused a huge tsunami that took out another 2,100 homes with its. 5–6-metre (16–20-foot) waves. At least 1362 dead, 2600 injured and 100 missing +
1703 Genroku Earthquake and Tsunami
The 1703 Genroku earthquake (Genroku Daijishin) occurred at 2:00am local time on December 31. The epicenter was near Edo, the forerunner of present-day Tokyo, in the southern part of the Kanto- Region, Japan. It shook Edo and an estimated 2,300 people were killed by the shaking and subsequent fires. The earthquake triggered a major tsunami which caused many casualties, giving a total death toll of at least 5,233, possibly up to 10,000. Genroku is a Japanese era spanning from 1688 through 1704. [Source: Wikipedia +]
The Genroku Earthquake is thought to have been an interplate earthquake whose focal region extended from Sagami Bay to the tip of the Boso Peninsula as well as the area along the Sagami Trough in the open sea southeast of the Boso Peninsula. It generated strong ground motion over a wide area centered in the southern Kanto region. Reports on the damage theorized that ground motion corresponded to a seismic intensity of 6 on the Richter scale. This earthquake then resulted in a tsunami that hit the coastal areas of Japan and the Boso Peninsula. The tsunami caused more than 6,500 fatalities on the peninsula. In Awa, Japan, however, the tsunami was reported to have killed more than 100,000 people — possibly the most destructive tsunami ever. [Source: History of Tsunamis in Japan, .stfrancis.edu]
The Kanto- Region lies at the complex triple junction, where the convergent boundaries between the subducting Pacific and Philippine Sea Plates and the overriding North American Plate meet. Earthquakes with epicenters in the Kanto region may occur within the Eurasian Plate, at the Eurasian Plate/Philippine Sea Plate interface, within the Philippine Sea Plate, at the Philippine Sea Plate/Pacific Plate interface or within the Pacific Plate. In addition to this set of major plates it has been suggested that there is also a separate 25 kilometers thick, 100 kilometers wide body, a fragment of Pacific Plate lithosphere. The 1703 earthquake is thought to have involved rupture of the interface between the Eurasian Plate and the Philippine Sea Plate. +
The earthquake was associated with areas of both uplift and subsidence. On both the Boso Peninsula and Miura Peninsula a clear paleo shoreline has been identified, indicating up to 5 meters of uplift near Mera (about 8 kilometers south of Tateyama) and up to 1.2 meters of uplift on Miura, increasing to the south. This distribution of uplift, coupled with modelling of the tsunami, indicate that at least two and probably three fault segments ruptured during the earthquake. +
The tsunami had run-up heights of 5 meters or more over a wide area, with a maximum of 10.5 meters at Wada and 10 meters at both Izu O-shima and Ainohama. About 400 kilometers of coastline was severely affected by the tsunami, with deaths being caused from Shimoda on the east coast of the Izu Peninsula in the west to Isumi on the east side of the Bo-so- Peninsula to the east. There was also a single death on the island of Hachijo-jima about 180 kilometers south of the earthquake's epicentre, where the tsunami was 3 meters high. The total number of casualties from earthquake, fires and tsunami has been reported as 5,233. Other estimates are higher, with 10,000 in total, and one source that gives 200,000. +
The area of greatest damage due to the earthquake shaking was in Kanagawa Prefecture, although Shizuoka Prefecture was also affected. The earthquake caused many large fires, particularly at Odawara, increasing both the degree of damage and the number of deaths. A total of 8,007 houses were destroyed by the shaking and a further 563 houses by the fires, causing 2,291 deaths. +
On 29 August 1741 the western side of Hokkaido was hit by a tsunami associated with the eruption of the volcano on Oshima island. The cause of the tsunami is thought to have been a large landslide, partly submarine, triggered by the eruption. 1,467 people were killed on Hokkaido and another 8 in Aomori Prefecture. [Source: Wikipedia]
1771 Great Yaeyama Tsunami
The 1771 Great Yaeyama Tsunami (also called the Great Tsunami of Meiwa) was caused by the Yaeyama Great Earthquake at about 8:00am on April 24, 1771, south-southeast of Ishigaki Island, part of present day Okinawa, Japan. According to records, there were 13,486 deaths including 8,439 persons killed on Ishigaki Island and 2,548 on Miyako Island. According to National Geographic the world's largest recorded tsunami was associated with this earthquake. It struck Yonaguni Jima with an estimated height of more than 131 feet (40 meters). [Source: Wikipedia +]
According to the Japanese government publication Rika-Nenpyo—or Chronological Scientific Tables—the epicenter was 40 kilometers south-southeast of Ishigaki Island with a magnitude of 7.4. According to the Mamoru Nakamura Laboratory, University of the Ryukyus, the earthquake was due to the activity of the fault east of Ishigaki and it is estimated that the magnitude was 7.5. Further simulation led to the activity of faults in the Ryukyu oceanic trench and the magnitude was 8.0. The depth was 6 kilometers (3.7 miles). This trench lies between the Philippine Sea. +
The dead and missing amounted to 12,000 people, and more than 2,000 houses were destroyed on Ishigaki and Miyakojima. Agriculture was severely damaged because of sea water invasion and the population decreased to about one third of what it was before the earthquake. On Ishigaki island, the wave was 40 to 80 meters high. There are many huge rocks believed to have been left by the earthquake. There was a legend that an islet disappeared, but this has never been verified.
Unzen Eruption, Earthquake and Tsunami in 1792
In 1792, the collapse of one of its several lava domes of Mt. Unzen—a volcano near present-day Nagasaki in Kyushu—triggered a megatsunami that killed about 15,000 people in Japan’s worst-ever volcanic-related disaster. The volcano was most recently active from 1990 to 1995, and a large eruption in 1991 generated a pyroclastic flow that killed 43 people, including three volcanologists. [Source: History of Tsunamis in Japan, .stfrancis.edu *+*]
Activity from 150,000 years ago to the present has occurred at a number of sites around the volcanic complex, building four main domes at different times: the No-dake (70–150,000 years old), Myo-ken-dake (25–40,000 years old), Fugen-dake (younger than 25,000 years old) and Mayu-yama (4,000 years old) volcanic peaks. Fugendake has been the site of most eruptions during the past 20,000 years and lies about 6 kilometers (3.7 miles) from the center of Shimabara, a town in the Shimabara Peninsula of Nagasaki Prefecture, Japan. *+*
Unzen’s deadliest eruption occurred in 1792, with a large dacitic lava flow coming from Fugen-dake. The east flank of the Mayu-yama dome collapsed unexpectedly following a post-eruption earthquake, creating a landslide. This caused a megatsunami that reached a height of 100 metres (330 feet), and killed an estimated 15,000 people. As of 2011 it is the worst volcanic related eruption in Japan. *+*
1792 Unzen earthquake and tsunami resulted from volcanic activities of Mount Unzen on May 21. The southern flank of the Mayuyama dome in front of Mount Unzen collpased, resulting in a tremendous tsunami. Many people were killed by this tsunami in Higo (Kumamoto Prefecture, situated 20 kilometers away across the Ariake Sea). The coastline of the Ariake Sea in area was dramatically changed by the event. [Source: Wikipedia +]
Towards the end of 1791, a series of earthquakes occurred on the western flank of Mount Unzen which gradually moved towards Fugen-dake (one of the Mount Unzen's peaks). In February 1792, Fugen-dake started to erupt, triggering a lava flow which continued for two months. Meanwhile, the earthquakes continued, shifting nearer to the city of Shimabara. On the night of 21 May, two large earthquakes were followed by a collapse of the eastern flank of Mount Unzen's Mayuyama dome, causing a landslide which swept through the city of Shimabara and into Ariake Bay, triggering a great tsunami. +
It is not known to this day whether the collapse occurred as a result of an eruption of the dome or as a result of the earthquakes. The tsunami struck Higo Province on the other side of Ariake Bay before bouncing back and hitting Shimabara again. Out of an estimated total of 15,000 fatalities, around 5,000 are thought to have been killed by the landslide, around 5,000 by the tsunami across the bay in Higo Province, and a further 5,000 by the tsunami returning to strike Shimabara. The waves reached a height of 33–66 feet (10–20 meters), classing this tsunami as a small megatsunami. At the Osaki-bana point Futsu town, the waves locally grew to a height of 187 feet (57 meters) due to the effect of sea bottom topography.
Lake Shirachi is a pond in Shimabara city, Nagasaki Prefecture which was created after the landslide at Mayuyama created by the inpouring of underground water. Its size was first 1 kilometers (south-north) and 300 meters to 400 meters (east to west), but the production of a water exit river made it smaller and it is now 200 meters by 70 meters. As a result of the destruction, Tsukumojima or 99 islets or rocks were distributed near Shimabara city. In the same Nagasaki Prefecture, there are 99 islands or Kuju-kushima distributed from Sasebo city to Hirado city. These islands are different from Tsukumojima.
After 1792, the volcano remained dormant until an earthquake swarm began about 20 kilometers (12 miles) underneath and 10 kilometers (6.2 miles) west of Fugendake in November 1989. Over the following year, earthquakes continued, their hypocentres gradually migrating towards the summit. The first phreatic eruptions began in November 1990, and after inflation of the summit area, fresh lava began to emerge on May 20, 1991.
Ansei Great Earthquakes
The Ansei Great Earthquakes (Ansei no Dai Jishin) were a series of three major earthquakes that struck Japan during the Ansei era (1854–1860). The 1855 earthquake was blamed on a giant catfish (Namazu) thrashing about. Ukiyo-e prints depicting namazu became very popular around this time. Other notable quakes to strike in the Ansei period include one in the Iga area, one which registered 7.4 on the Richter scale and struck Kyushu and Shikoku . [Source: Wikipedia +]
The Ansei-To-kai Quake (Ansei To-kai Jishin) was an 8.4 magnitude earthquake which struck on December 23, 1854. The epicenter ranged from Suruga Bay to the deep ocean, and struck primarily in the To-kai region, but destroyed houses as far away as in Edo. The accompanying tsunami caused damage along the entire coast from the Bo-so- Peninsula in modern-day Chiba prefecture to Tosa province (modern-day Ko-chi prefecture) The Ansei-Nankai Quake (Ansei Nankai Jishin) was an 8.4 magnitude earthquake which struck on December 24, 1854. Over 10,000 people from the To-kai region down to Kyushu were killed. +
The Ansei Edo Quake (Ansei Edo Jishin) was a 6.9 magnitude earthquake which struck Edo (modern-day Tokyo) on November 11, 1855. One hundred and twenty earthquakes and tremors in total were felt in Edo in 1854-55. The great earthquake struck after 10 o'clock in the evening; roughly 30 aftershocks continued until dawn. The epicenter was near the mouth of the Arakawa River. Records from the time indicate 6,641 deaths inside the city, and 2,759 injuries; much of the city was destroyed by fire, leading many people to stay in rural inns. Aftershocks continued for twenty days. This quake was a particularly destructive deep thrust quake caused by a giant slab of rock stuck between the Philippine Sea Plate and the Pacific Plate. +
1911 Kikai Island Earthquake and Tsunami
The 1911 Kikai Island earthquake (1911Sen-kyu-hyaku-jyu-ichi-nen Kikai-jima Jishin) occurred on June 15, 1911 at 11:26pm local time. The earthquake was located near Kikai Island, Japan. It had a magnitude of Ms 8.1. The earthquake occurred near the northern end of the deepest region in Ryukyu Trench. The hypocenter was located near 28.00̊E, 130.00̊N, about 30 kilometers south of the Kikai Island, with a depth of about 100 km. However, due to the instrumental precision of that time, the location of the hypocenter was just an approximation, and estimations differ. A recent study estimated that the hypocenter was located near 28.90̊E, 130.25̊N, about 60 kilometers NNE of the Kikai Island, with a depth of about 30 km. [Source: Wikipedia +]
Twelve people were reported dead, including one on Kikai Island. Four hundred and twenty two houses were completely destroyed, 401 of which on Kikai Island. Damage was also reported on Amami O-shima, Toku-no-shima, and Okinawa Island. The wall of Shuri Castle in Shuri was damaged. A tsunami was triggered by the earthquake, which was recorded on Kikai Island and Amami O-shima. This earthquake could be felt as far as in Shanghai, China, Tainan, Taiwan (then under Japanese rule), and Fukushima, Japan. +
Tsunami During the 1923 Tokyo Earthquake
The morning of Saturday, September 1, 1923, was very hot with strong gusts of wind that followed rain. Soon it was almost noon and the area around Sagami Bay, Japan began to shake in what amounted to a magnitude 8.3 earthquake. A section of the fault under the bay was measured to have been displaced nearly 240m, and although no surface faults appeared, new ridges 180 to 300 feet tall appeared on the sea floor in line with a pre-existing volcanic chain. The ground was uplifted and hundreds of landslides were triggered. This Kanto Earthquake generated a tsunami approximately 30-40ft high which crashed unto shore about 5 minutes later. Many were killed, houses were destroyed, and nearly 45 percent of the population was left unemployed. [Source: History of Tsunamis in Japan, .stfrancis.edu *-*]
In all, seven prefectures were affected by the tsunami. These were Tokyo, Kanagawa, Shizuoka, Chiba, Saitama, Yamanashi, and Ibaraki. The greatest destruction occurred at Yokohama, which at the time was the premier commercial port of Japan. An unusual characteristic of the Great Kanto Earthquake was the dramatic upheaval and depression of the ground. The earth was uplifted as high as 24ft, substantially changing the shape of the shoreline. *+*
No less ferocious in nature than the earthquake itself was the conflagration that followed. When it struck, coal or charcoal cooking stoves were in use throughout Toyko and Yokohama in preparation for the noon-time meal and fires sprang up everywhere within moments of the quake. Fire-induced wind spawned numerous cyclones, which further spread the flames. The uplifting and depression of the land also resulted in landslides. Towns were buried by a massive mudflow, killing hundreds. [Source: Wikipedia +]
The combination of the earthquake and tsunami created massive destruction. The total number of houses partially or completely destroyed numbered in excess of 694,000. In addition to houses, the list of damage includes buildings, dams, tanks, tunnels, sewers, towers, canals, retaining walls, and lighthouses. Telephone and telegraph systems were demolished leaving the people completely cut off from the outside world. Streets were choked with rubble making them impassible by automobile. +
Because the earthquake struck at lunchtime when many people were cooking meals over fire, many people died as a result of the many large fires that broke out. Some fires developed into firestorms that swept across cities. Many people died when their feet became stuck in melting tarmac. The single greatest loss of life was caused by a fire tornado that engulfed open space at the Rikugun Honjo Hifukusho (formerly the Army Clothing Depot) in downtown Tokyo, where about 38,000 people were incinerated after taking shelter there following the earthquake. The earthquake broke water mains all over the city, and putting out the fires took nearly two full days until late in the morning of September 3. An estimated 6,400 people were killed and 381,000 houses were destroyed by the fire alone. +
A strong typhoon struck Tokyo Bay at about the same time as the earthquake. Some scientists, including C.F. Brooks of the United States Weather Bureau, suggested the opposing energy exerted by a sudden decrease of atmospheric pressure coupled with a sudden increase of sea pressure by a storm surge on an already-stressed earthquake fault, known as the Sagami Trough, may have triggered the earthquake. Winds from the typhoon caused fires off the coast of Noto Peninsula in Ishikawa Prefecture to spread rapidly. +
Many homes were buried or swept away by landslides in the mountainous and hilly coastal areas in western Kanagawa Prefecture, killing about 800 people. A collapsing mountainside in the village of Nebukawa, west of Odawara, pushed the entire village and a passenger train carrying over 100 passengers, along with the railway station, into the sea. +
A tsunami with waves up to 10 meters (33 feet) high struck the coast of Sagami Bay, Bo-so- Peninsula, Izu Islands, and the east coast of Izu Peninsula within minutes. The tsunami killed many, including about 100 people along Yui-ga-hama Beach in Kamakura and an estimated 50 people on the Enoshima causeway. Over 570,000 homes were destroyed, leaving an estimated 1.9 million homeless. Evacuees were transported by ship from Kanto to as far as Kobe in Kansai. The damage is estimated to have exceeded USD$1 billion (or about $13,701 billion today). There were 57 aftershocks. +
Altogether, the earthquake and typhoon killed an estimated 99,300 people, and another 43,500 went missing.
See Tokyo Earthquake
Tsunamis in Japan in Recent Years
According to the Japan Meteorological Agency, the March 4, 1952 Tokachi-oki Earthquake corresponded to a seismic intensity of 8.1. The maximum tsunami height reached 3 to 4m on the Pacific coast f eastern Hokkaido. It caused 28 deaths, injured 287, and destroyed 8,534 houses.
In July 1993, an earthquake hit Okushiri Island, off southwestern Hokkaido. It measured 8.1 on the Richter scale and produced a 10-meter tsunami that washed away many homes and buildings . The tsunami 232 people, destroyed 1,410 houses and caused $500 million in damage. Some victims were killed in high water, landslides and collapsed buildings caused by the tsunami.
damage from 2003 Hokkaido earthquake and tsunami
On September 26, 2003, a powerful earthquake struck eastern Hokkaido. Measuring 8.0 on the Richter scale, the quake was located 50 miles off shore and 30 miles below the surface of the sea. A total of 573 people were hurt; 41,000 were evacuated; an oil refinery caught fire; and a train derailed. The main earthquake was followed by a strong earthquake measuring 7.1 on the Richter scale. Much of the damage was caused by a tsunami that reached a height of 1.2 meters in Kushiro in Hokkaido. The tsunami hit about one hour after the earthquake. One man told the Daily Yomiuri, “When a big wave approached the port, I thought it would swallow me and my car whole.”
About two dozen Japanese were killed in Thailand and Sri Lanka by the tsunami in 2004.
In September 2004, a series of powerful under sea earthquakes off of Honshu produced tsunami waves 86 centimeters high in Wakayama. . A powerful and shallow earthquake off of northern Japan produced tsunami waves several centimeters high.
1983 Sea of Japan Earthquake and Tsunami
A tsunami caused by an earthquake in Miyagi Prefecture in northeast Honshu in May 1983 killed 100 people, including a group of elementary school children having picnic on the beach and were swallowed up by a tsunami. The tsunami occurred on May 26, 1983, at the middle of the East Sea and propagated across the basin and caused substantial damages along the coasts of Japan and Korea. The tsunami, generated by a magnitude 7.9 earthquake destroyed 700 boats and 59 houses for a total of $800 million in property damage in Japan. A total of 104 people killed or missing in Japan (many drowned in the tsunami) and 324 were injured. Three people were killed in Korea. The earthquake itself damaged 5,100 houses and ended several lives. As a result of the combination of earthquake and tsunami, a process of liquefaction occurred. Liquefaction happens in areas where unconsolidated materials are saturated with water. Under these conditions, what had been a stable soil turns into a fluid that is not capable of supporting buildings or other structures. [Source: History of Tsunamis in Japan, .stfrancis.edu *+*]
The 1983 Sea of Japan earthquake or 1983 Nihonkai-Chubu earthquake occurred at 11:59am local time. Measuring 7.8 on the moment magnitude scale, it occurred in the Sea of Japan, about 100 kilometers west of the coast of Noshiro in Akita Prefecture, Japan. Out of the 104 fatalities, all but four were killed by the resulting tsunami, which struck communities along the coast, especially Aomori and Akita Prefectures and the east coast of Noto Peninsula. Images of the tsunami hitting the fishing harbor of Wajima on Noto Peninsula was broadcast on TV. The waves exceeded 10 meters (33 feet) in some areas. Three of the fatalities were along the east coast of South Korea (whether North Korea was affected is not known). The tsunami also hit Okushiri Island, the site of a more deadly tsunami 10 years later. [Source: Wikipedia +]
The northwestern side of Honshu lies on the southeastern margin of the Sea of Japan, an area of oceanic crust created by back-arc spreading from the late Oligocene to middle Miocene. The extensional tectonics associated with the spreading formed a series of N-S trending extensional faults and associated basins. Currently the area is being deformed by contractional tectonics, causing inversion of these earlier basins, forming anticlinal structures. It has been suggested that the northwestern coast of Honshu represents an incipient subduction zone, but there remain significant uncertainties about the existence of the Okhotsk Plate and the nature and precise location of its boundary in the Sea of Japan, if it does exist. +
The earthquake lasted for about 60 seconds. The focal mechanism indicates reverse faulting and the distribution of aftershocks is consistent with movement on a thrust plane dipping at 30̊ to the east. The rupture involved two separate faults, the more northerly of which trends NNW-SSE and the more southerly SSW-NNE. The rupture began on the southern fault before continuing on the northern fault after a delay of ten seconds. The maximum perceived intensity was V on the JMA scale (VIII on the Mercalli Intensity Scale). Much of the earthquake damage was due to soil liquefaction, causing the collapse of houses and a number of road and rail accidents. The degree of liquefaction was the worst seen in Japan since the 1964 Niigata earthquake. The greatest effects were observed in areas underlain by loose Holocene aeolian and fluvial sands. Four people were killed by the effects of the earthquake shaking. +
Details of the Tsunami from 1983 Sea of Japan Earthquake and Tsunami
The first wave of the tsunami struck the coast about 12 minutes after the earthquake, with a maximum run-up height of 14.9 meters (49 feet) recorded on the Oga Peninsula. The initial models of the earthquake were unable to reproduce the short time interval between the shock and the first wave arrival at the coast. The possibility that the faults dipped to the west, which would have brought the tsunami source closer to the coast, was inconsistent with seismic data and slow aseismic slip on the southern fault immediately before the mainshock has been proposed as an explanation. [Source: Wikipedia +]
Tsunami deposits associated with this earthquake have been recognised onshore, on the coast and in the Sea of Japan. Offshore both mass failure deposits and turbidites have been observed that are dated to later than 1954 from high Caesium-137 levels in the overlying sediments. +
Tsunami warnings were issued 14 minutes after the earthquake, but many parts of the nearby coast were struck before any action could be taken. Many people were struck by the first wave either on the shoreline or on offshore building sites and there were a hundred deaths. The tsunami caused widespread damage to coastal defences, which had been designed for storms rather than tsunamis. The tsunami reached the coast of South Korea about 1–1½ hours after the earthquake, causing the death of three people. +
1993 Hokkaido Earthquake and Tsunami
On the night of July 12, 1993, their preparations faced a magnitude 7.8 earthquake in the Sea of Japan generated a tsunami that struck various parts of the small island of Okushiri. Five minutes after the main shock the Japan Meteorological Agency issued a warning over television and radio that a major tsunami was on its way. By then, 10- to 20-meter waves had struck the coastline nearest the sources, claiming a number of victims before they could flee. However, 1,200 people escaped the waves when they ran inland after feeling the shaking. [Source: History of Tsunamis in Japan, .stfrancis.edu *+*]
The $600 million in property losses were attributed to the tsunami. This tsunami causes spectacular localized damage, especially on the southwestern shores of Hokkaido and on Okushiri Island. Numerous fires, fueled by above-ground kerosene and propane tanks, broke out following the tsunami, adding to the property loss and misery. The tsunami stripped plants and grasses from the hillside leaving debris in the overhead utility wires. Vertical runup measurements varied between 15 and 30m over a 20km portion of the southern part of Okushiri Island, with several 10m values on the northern portion. As of July 21, 185 fatalities were confirmed, with 120 attributed to the tsunami.
The 1993 Hokkaido Earthquake (Hokkaido- Nansei Oki Jishin) occurred at 1:17pn local time. Measuring 7.7 on the moment magnitude scale with a maximum felt intensity of VIII (Destructive) on the Mercalli intensity scale, it triggered a major tsunami that caused deaths on Hokkaido- and in southeastern Russia, with a total of 230 fatalities recorded. The island of Okushiri was hardest hit, with 165 casualties from the earthquake, the tsunami and a large landslide. [Source: Wikipedia +]
The earthquake occurred in the backarc region of the convergent boundary where the Pacific Plate subducts beneath the Eurasian Plate. The earthquake shaking caused moderately severe damage, VIII on the Mercalli scale. The earthquake had two distinct shocks. The first lasted for 20 seconds, while the second lasted 35 seconds. The rupture occurred on a fault that dipped at 24 degrees to the east. It had an estimated length of 150 kilometers with a displacement of 2.5 meters. The island of Okushiri subsided by 5–80 centimeters. The Okushiri-port landslide involved a volume of 1.5 x 105 m³ of rock. The slide failure occurred at the base of a volcanic breccia bed. The slide occurred in two phases that may match the two separate shocks recorded for the earthquake. +
The tsunami reached Okushiri between 2 and 7 minutes after the earthquake. A tsunami warning was given 5 minutes after the earthquake by the JMA. However, this was too late for the inhabitants of Okushiri. The quake caused fires to start in the town of Okushiri, adding greatly to the total damage. The tsunami inundated large parts of Okushiri, despite its tsunami defenses. Okushiri had been struck by another tsunami 10 year earlier. A maximum run-up of 32 meters was recorded on the western part of the island near Monai. A tsunami was widely observed in the Sea of Japan with a run-up of 3.5 meters at Akita in northern Honshu, up to 4.0 meters in southeastern Russia and up to 2.6 meters on the coast of South Korea. +
The destructive power of this tsunami led to an overhaul of the sea defences on Okushiri involving the construction of tsunami sluices on a river and strengthened embankments. New escape routes were also provided and help was given for households to purchase emergency broadcast receivers. +
Tsunami Caused by Chilean Earthquake in 2010
In February 2010, the Pacific Coast of Japan was struck by a small tsunami generated by a powerful earthquake 17,000 kilometers---half a world away--- in Chile that reached Japan the day after the earthquake occurred. The largest tsunami, a 120-centimeter-high surge, was observed at Kuji Port in Iwate Prefecture. A 110-centimeter-high tsunami was seen at Sendai Port in Miyagi and Shibusho Port in Kagoshima Prefecture . Damage was minor: a few building were flooded . Perhaps most remarkably the tsunami traveled 20 kilometers up a river that emptied into Sendai Bay. Tsunami expert Hitoshi Tanaka of Tohuku University told the Yomiuri Shimbun, “In the case of a gently inclining river, a tsunami can travel upriver for long distances and cause flood damage inland. Residents living near rivers have to be careful.”
Tsunami waves generated by the Chilean earthquake kept coming for 20 hours. They were triggered when the seabed and water were raised by a massive amount of energy, created by movement along a 600-kilometer-long fault near Chile.
The greatest damage was suffered by oyster and scallop producers in Miyagi and Iwate Prefectures, where the back surge from the tsunami waves flipped over rafts used to oyster and scallop cultivation. . In some cases the ropes that held the rafts were severed by the tsunami and the rafts floated away. On one group of islands in Miyagi Prefecture , 90 percent of the 180 rafts used to raise nori seaweed were destroyed.
The first major tsunami warning in 17 years was issued after the Chilean quake. Advisories, messages and bulletins were broadcast all day long on television with maps showing areas expected to be struck and estimates of the size of tsunamis expected. The Japan Meteorological Agency predicted tsunamis up to three meters in high, which are capable of being quite destructive. In some places train operations were halted and evacuation orders were given. After the event the Japan Meteorological Agency apologized for not only inaccurately predicting the height of waves but also forecasting earlier landfalls than actually occurred.
One survey found that only 6.2 percent of those requested to seek shelter from the tsunami actually did so. Of the 340,000 residents in 36 cities, towns and villages in Aomori, Iwate and Miyagi Prefecture asked to evacuate, only 21,000 sought shelter in designated areas. The others either stayed at home or went somewhere else. On restaurant workers who continued working after the warning was issued told the Yomiuri Shimbun, “The bank here is very high and there’s an evacuation center nearby so we could flee to safety right away if we had to . We were safe when when tsunami caused by [another] Chile earthquake hit here 50 year ago.” Also worrisome was the fact that many of those that did evacuate returned home after the first wave, a dangerous move considering that the most dangerous waves often appear after the first one.
Small Tsunami Hits Japan after 7.3-magnitude Quake
In December 2012, Associated Press reported: “A strong earthquake struck the same Japanese coast devastated by last year's massive quake and tsunami, generating small waves but no immediate reports of heavy damage. Several people along the northeastern coast were reportedly injured and buildings in Tokyo and elsewhere swayed for several minutes. The earthquake had a preliminary magnitude of 7.3 and struck in the Pacific Ocean off the coast of Miyagi prefecture at 5:18 pm, the Japan Meteorological Agency said. The epicentre was 10 kilometers beneath the seabed and 240 kilometers offshore. [Source: Associated Press, December 8, 2012 //\\]
“The area was shaken by repeated, smaller aftershocks, the agency said. After the quake, authorities issued a warning that a tsunami potentially as high as 2 metres could hit. Sirens whooped along the coast as people ran for higher ground. Ishinomaki, in Miyagi, reported a tsunami 1 metre high and other towns reported smaller tsunamis. About two hours after the quake struck, the tsunami warning was cancelled. The Pacific Tsunami Warning Centre earlier said there was no risk of a widespread tsunami. //\\
Aiko Hibiya, a volunteer for the recovery in Minami-Sanriku, a coastal town devastated by last year's tsunami, said she was at a friend's temporary housing when the quake struck. "It shook for such a long time," she said. Japan has barely begun to rebuild from last year's magnitude-9.0 earthquake, which triggered a tsunami that swelled to 20 meters high in some areas, killing about 19,000 people and displacing over 325,000 people, who now live in barracks and other temporary quarters. Public television broadcaster NHK reported that five people were injured, including a 75-year-old woman in Miyagi who fell while fleeing the tsunami. Police said they could not immediately confirm those reports. //\\
In late December 2012, an earthquake with an estimated magnitude of 7.1 on the open-ended Richter scale jolted mainly eastern and northeastern Japan early Saturday, triggering a small tsunami in Pacific coastal areas. [Source: The Japan News, December 26, 2013]
Small Tsunami Reach Japan from Solomon Quake
A 40-centimeter-high tsunami were observed at Hachijo Island in the Izu chain off Tokyo following an 8.0-magnitude earthquake that rocked the Solomon Islands in the South Pacific, the Meteorological Agency said. A tsunami about 10 centimeters high were also observed at Chichijima in the Ogasawara island chain, at Owase in Mie Prefecture, as well as at Kushimoto and Nachikatsuura, both in Wakayama Prefecture, the agency said. [Source: Kyodo, Jiji, February 7, 2013]
Observation data from other locations along the Pacific coast were mostly within the range of 10 to 20 centimeters or less. The Solomon quake prompted the agency to issue a tsunami alert for Japan’s Pacific coast. At 2:41 p.m., the agency warned that tsunami of up to 50 centimeters high could reach the Pacific coast between Hokkaido and Okinawa. The agency urged people to stay away from the shore and warned that the first tsunami is not necessarily the highest if it originated in a distant location. The powerful earthquake occurred near the Solomon Islands at 12:12 p.m. local time. Tsunami 91 centimeters high were observed in the Santa Cruz Islands.
Thirty-Five -Meter-High Tsunami May Hit Hokkaido
Hokkaido's Pacific coast, the Yomiuri Shimbun reported, may be hit by tsunami as high as 35 meters if a massive earthquake strikes near Hokkaido, according to an interim report by an expert panel at the Hokkaido Disaster Management Council. The experts, led by Minoru Kasahara, a professor emeritus at Hokkaido University, raised the maximum predicted magnitude of an earthquake near Hokkaido from 8.6 to 9.1 based on sediments collect from past tsunami. [Source: Yomiuri Shimbun, April 22, 2012]
“As a result, the maximum height of the tsunami could be as high as 35.1 meters at Tokachi Port in Hiroo, Hokkaido. The figure exceeds the Cabinet Office's 34.4-meter predicted height for a tsunami in Kuroshio, Kochi Prefecture, in the event of a massive quake in the Nankai Trough. According to the projections, a tsunami of 30 meters or higher could strike five towns in Hokkaido, while a tsunami between 20 meters and 30 meters could hit another six cities and towns, including Kushiro. [Ibid]
“In the panel's simulations, the epicentral area of the massive earthquake was estimated to be in areas off northern Sanriku to the Nemuro coast. It is presumed that a magnitude-8 earthquake will occur about every 500 years at the boundary of the tectonic plate extending from areas off Tokachi to areas off Nemuro. The Hokkaido government had previously predicted that the largest possible earthquake would have a magnitude of 8.6 and trigger a tsunami with a maximum height of 22 meters. However, based on lessons learned from the Great East Japan Earthquake, institutions have begun forecasting the worst possible earthquakes that may occur once every several hundreds of years, or every 1,000 years. [Ibid]
Videos of the 2011 Tsunami
Collections of Tsunami Video
Collection of Videos of the 2011 Tsunami
Collection of videos of the 2011 Tsunami
Collection of Videos
Video of Geology of 2011 Tsunami
Geology of 2011 Tsunami
Video of 2011 Earthquake in Northern Japan
Moment the Earthquake Hits
Running Outside During Earthquake
Video of Tsunami Waves and Whirlpools
View of Tsunami from Ship at Sea
Video of Tsunamis Waves Coming Ashore
Tsunami Comes Ashore
Helicopter Shot of Waves Coming Ashore and Devastating Land
Tsunami Overcomes Sea Wall
Ground Level Footage of Tsunami
Wave Coming in Oirase
Video of Boats and Cars Tossed by Tsunami
Boats Crashing Ashore in Sendai
Tsunami Smashes a Boat
Tsunami Hits Parking Lot and Cargo Area, Carry Away Ships
Strike Sendai Airport
Video of Tsunamis Hitting Towns
Black Tsunami Goes Over Wall in Miyako
Tsunami Comes Ashore in Miyako
Tsunami and Fire, Tsunami Spread on Land
Tsunami Hits Aomori
Tsunami Smashes Through the Middle of a Town in Iwate
Tsunami Rushes Up a River
Earthquake and Tsunami Through Middle of Town
Video of Tsunami Hitting Sendai Area
Helicopter Shots of Fire and Damage in Sendai
Refinery Fire in Ichihara
Video of Tsunami Hitting Minamisanriku
Huge Waves Come Ashore, Minamisanriku
Escaping Tsunami in Minamisanriku and Tagajo
Tsunami Hits Minamisanriku
Video of Tsunami Flooding
CCTV video of Tsunami Flooding and Earthquake
Video of Tsunami Survivors
Man Rescued at Sea
Video of Tsunami Survivor Stories
Preparing for the Tsunami
Running from Tsunami, Survivor Story
Tsunami Comes Ashore as People and Cars Make a Run for It
Tsunami Hits Person in a Car
Survivor Story from Young Boy
NPR, Survivors Dig Out in
Survivor Story, Running for Cover, Examining Damage
Mother and Baby Narrowly Escape Tsunami
Damage and Survivor Story from Kamaishi
Image Sources: USGS, Tokyo University, YouTube,
Text Sources: New York Times, Washington Post, Los Angeles Times, Times of London, Yomiuri Shimbun, Daily Yomiuri, Japan Times, Mainichi Shimbun, The Guardian, National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.
© 2008 Jeffrey Hays
Last updated January 2014