LARGE EARTHQUAKES IN JAPAN

WORST RECORDED EARTHQUAKES

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Tokyo 1923
An earthquake in northern Japan in A.D. 869 is believed to have been the strongest earthquake to hit Japan in historical times. Based on evidence of a tsunami produced by the quake along the Pacific coast it was estimated to have had a magnitude of 9 on the Richter scale. About 1,000 people are thought to have been killed by a tsunami produced by the quake that dumped water three kilometers inland in the Sendai area.

Worst Recorded Earthquakes (number of dead): 1) Shaanxi, China, Jan. 24, 1556 (830,000); 2) Calcutta, India, Oct. 11, 1737 (300,000); 3) Tangshan, China, July 28, 1976 (242,000); 4) Antioch, Syria, May 20, 526 (240,000); 5) December 26, 2004, Sumatra in 2004 (225,000); 6) Yokohama , Japan, Sept. 1, 1923 (200,000); 7) Nan-Shan, China, May 22, 1927 (200,000); 8) Hokkaido Japan , Dec. 30, 1730 (137,000); 9) Chihli, China, Sept. 27, 1290 (100,000); 10) Gansu, China, Dec. 16, 1920 (100,000); 11) Sichuan China, May 12, 2008 (90,0000); 12) (100,000) Messina, Italy, Dec. 28, 1908 (83,000); 13) Shemaka, Caucasia, Nov. 1667 (80,000); 14) Gansu, China, Dec. 26, 1932 (70,000); 15) Northern Peru, May 31, 1970 (66,794); 16) Cilicia, Asia Minor, 1268 (60,000);

17) Catania, Italy, Jan. 11, 1693 (60,000); 18) Lisbon, Portugal, Nov. 1, 1755 (60,000); 19) Armenia, Dec. 7, 1988 (55,000); 20) Quetta, India, May 31, 1935; 21) Corinth, Greece, 856 (45,000); 22) Quito, Ecuador, Feb. 4, 1797 (41,000); 23) Northwest Iran, June 21, 1990 (40,000+); 24) N. Persia, June 7, 1755 (40,000); 25) Peru, Ecuador, Aug 13-15, 1868 (40,000); 26) Kamakura, Japan , May 20, 1293 (30,000); 27) Lisbon, Portugal, Jan 26, 1531 (30,000); 28) Calabria, Italy, Feb. 4, 1783 (30,000); 29) Echigo, Japan , Dec. 28. 1828 (30,000); 30) Erzincan, Turkey, Dec. 26, 1939 (30,000); 31) Avezzano, Italy, Jan. 13, 1913 (29,980); 32) Chilean, Chile, Jan. 24, 1939 (28,000);

An earthquake in Tokyo in 1855 left more than 10,000 people dead. An earthquake in 1927 raised the land along two faults by more than two meters. The tectonic makeup of Tokyo and surrounding areas is complicated, with two ocean plates subducting below a land plate on which the Japanese archipelago is located. There have been many earthquakes in this area, as both plate-boundary quakes, which are caused by friction between the plates, and inland quakes, which are caused by faults in the plates, can occur.

Study Reveals Five Huge Ancient Kanto Quakes

In September 2012, Jiji ress reported: “At least five huge earthquakes similar to the magnitude-7.9 Great Kanto Earthquake in 1923 hit the region between 4,000 and 2,000 years ago, researchers have revealed.In the study, researchers from the University of Tsukuba, the University of Tokyo, Tohoku University and other institutions analyzed sediments brought by tsunami to the southeast coast of the Miura Peninsula in Kanagawa Prefecture. They found evidence that massive earthquakes with a magnitude of about 8 on the Richter scale occurred in the Kanto region at least five times--2,000 years ago, 3,000 years ago, 3,300 years ago, 3,700 years ago and 4,000 years ago. [Source: Jiji Press, September 25, 2012]

It is already known that earthquakes as powerful as the 1923 quake that devastated Tokyo and surrounding areas periodically occur due to the subduction of the Philippine Sea Plate under the North American Plate along the Sagami Trough, which stretches beneath the Pacific Ocean off the Kanto region.In 2004, a government study team estimated after analyzing existing data that the 1923-type quakes have a recurrence interval of about 200 to 400 years. [Ibid]

Massive 794 Earthquake Thought to be a Nankai Earthquake

A massive earthquake believed to be a Nankai earthquake occurred in 794 when the capital was transferred from Heijokyo in Nara Prefecture to Heiankyo in Kyoto Prefecture, according to historical documents, Katsunori Imazu, an associate professor at Okayama University told the Yomiuri Shimbun. Nankai earthquakes are believed to occur in 100-year cycles, but historical documents from a 200-year period before and after the earthquake have not been found. Imazu said the 794 earthquake occurred in the middle of this blank period. [Source: Yomiuri Shimbun, April 20, 2012]

“Imazu found a statement that suggests the occurrence of a massive earthquake in a historical document called Nihon Kiryaku, which was compiled in the Heian period (794-1192) and summarizes the contents of Nihon Koki, an officially commissioned Japanese history text. The statement dated July 10, 784, says: "The earthquake hit the imperial court as well as the government quarters and houses in Keiki [modern-day Kyoto and its surrounding areas]. People died due to the earthquake." He also found statements related to the earthquake that said the Nankaido, an ancient road along the coast of Shikoku, was shut down and a new road was built two years later. Imazu concluded the 794 earthquake was a Nankai earthquake because the epicentral area was estimated in the Pacific, and said the Nankaido was closed due to a tsunami following the quake. [Ibid]

A trough is an underwater depression, or trench, lies at the intersection of a plate on the land side and a plate on the sea side.. The Nankai Trough originates from Suruga Bay, west of the Izu Peninsula. It extends to the seabed off the southern part of the Japanese archipelago, which is about four kilometers deep off the Shikoku and Kyushu regions. Along the Nankai Trough, the Philippine Sea Plate is moving beneath a land-side plate at a rate of several centimeters per year, dragging with it part of the latter at the point where they meet. When the land-side plate has been pulled to a certain extent, it is bound to spring back with tremendous force. This is how a massive earthquake occurs where plates meet. [Source: Yomiuri Shimbun, April 17, 2012]

Jogan Earthquake and Tsunami in A.D. 869

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. +

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.

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. +

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]

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. +

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.

Impact of Earthquakes and the Disasters in the Ansei Era (1854-1860)

Masayuki Yamauchi is a professor at the University of Tokyo's Graduate School of Arts and Science, wrote in the Yomiuri Shimbun, “During the Ansei era (1854-1860), a host of devastating earthquakes and epidemics occurred, compounded by domestic political crises, forcing the political leaders of the day to rise to challenges. In 1854, the first year of the Ansei era, when the Tokugawa shogunate bowed to Commodore Matthew Perry in opening Japan to the United States, the Great Tokai Earthquake and the Great Nankai Earthquake, both magnitude-8 tremors, and the magnitude-7.4 Great Hoyo Earthquake occurred, causing terrible tsunami damage to Pacific coastal areas. In October 1855, the magnitude-6.9 Ansei Edo Great Earthquake battered the capital. One of its most prominent victims was Fujita Toko, a senior Mito domain official, who was crushed to death. Yet, this temblor was smaller than the magnitude-7.4 quake that rocked the Iga Ueno area---now in Mie Prefecture---in June 1854.” [Source: Masayuki Yamauchi, Yomiuri Shimbun. May 8, 2011]

“In 1856, a typhoon swept through the Izu Peninsula and the northern parts of Edo, now Tokyo, causing widespread floods along the Tonegawa and Arakawa rivers, killing about 100,000 people. An influenza epidemic in 1857 was followed by cholera epidemic that claimed the lives of 100,000 to 300,000 people. The cholera was brought to Japan by a U.S. naval fleet. In 1859, a large number of people died from a measles outbreak, an event known as the Great Ansei Mashin (measles).” [Ibid]

“In the face of these calamities, the Ansei "prime ministers" of the shogunate, Abe Masahiro and Hotta Masayoshi, did not hesitate to pick up the gauntlet with extraordinary resolution and courage. Hotta assumed the post of chief of the Council of Elders (roju)---ranking immediately below the shogun---only a week after the 1855 Edo earthquake and started tackling a series of internal and external difficulties.”

“Even before taking up his new post, Hotta ordered shelters erected for quake victims two days after the earthquake, had emergency kitchens provide food and ordered emergency rice distribution. By today's standards, he acted extremely swiftly...The Tokugawa shogunate, however, continued to weaken as it was forced to carry out emergency fiscal spending to finance disaster reconstruction. If the Ansei streak of calamities had not occurred, the shogunate might not have helplessly yielded to the alliance of the rebellious Satsuma and Choshu domains, both of which suffered almost no damage from the natural catastrophes. By extension, measures taken against disasters and reconstruction efforts elsewhere would have imposed political challenges so serious they could have upended any regime.

Famous Earthquakes in Japan in the 19th and 20th Centuries

On October 28, 1891, a devastating quake hit the former provinces of Mino and Owari. Records show that there tragedy caused 7,273 deaths and 17,175 casualties. Based on the destruction, the Mino-Owari Earthquake is estimated that the Richter Scale hit a magnitude of 8.0. [Source: Time.com, Japan's History of Massive Earthquakes]

The 1946 Nankaido Earthquake. On December 20, an earthquake occurred in the submarine region of the Nakai Trough, a zone where large earthquakes have been reported since the 7th century. The tremors were felt from the northern parts of Honshu to Kyushu, Japan's southern island. The devastation destroyed approximately 36,000 homes and left about 1,360 dead, 2,600 injured and another 100 people missing. In addition, the quake triggered a tsunami that destroyed about 2,100 homes. [Ibid]

The 1948 Fukui Earthquake. On June 28th a 7.1 magnitude earthquake struck the Chubu region of Honshu at 5:13pm. The intense tremors hit the city of Fukui the hardest, causing the collapse of the Nakazuno Bridge and liquefaction, by which the violent shakes and vibrations of the quake cause loosely packed soil to behave like liquid, making it unable to support building foundations. An estimated 67,000 homes were destroyed and 3,894 civilians lost their lives in the tragedy. [Ibid]

The 1964 Niigata Earthquake. A 7.6 magnitude quake ferociously shook the northwest coast of Honshu, Japan's largest island, on June 16th at 1:01pm, causing liquefaction and claiming the lives of 26. [Ibid]

The 1978 Miyagi Earthquake. This June 12th quake hit at 5:14 PM, rocking the northeastern part of Honshu with a 7.7 magnitude, causing massive landslides that destroyed over 1,100 homes houses and killed 28 people. This earthquake was so catastrophic that in 1981, the Building Standard Law was revised to require stricter seismic design codes. [Ibid]

Worst Earthquakes in Japan in the 20th Century


1923 Tokyo Earthquake
Worst earthquakes in Japan in the 20th century (date; magnitude; dead; destroyed buildings): 1) Tokyo Earthquake (September 1, 1923; 7.9; 142,807; 576,262) 2) Kobe Earthquake (January 17, 1995; 7.2; 6,435; 512,880); 3) Fukai Earthquake (June 28, 1948; 7.1; 3,848; 39,111); 4)Sanriku Offshore Earthquake (March 3, 1933; 8.1; 3,008; 7,479); 5) Kita-Tango Earthquake (March 7, 1927; 7.3; 2,925; 16,295); 6) Mikawa Earthquake (January 13, 1945; 6.8; 2,306; 12,142; 7) Nankai Earthquake (December 21, 1946; 8.0; 1,432; 15,640); 8) Tottori Earthquake (September 19, 1943; 7.2; 1,083; 7,736); 9) Tonankai Earthquake (December 7, 1944; 7.9; 998; 29, 189). 10) Kita-Tajima Earthquake (May 23, 1925; 6.8; 428; 3,475)

Most deadly earthquakes since 1900 (magnitude on the Richter scale): 1) China in 1976, 255,000 dead (7.5);2) Sumatra in 2004, 225,000 dead (9.3); 3) China in 1927, 200,000 dead (7.9); 4) China in 1920, 200,000 dead (8.6); 5) Japan in 1923 , 143,000dead (7.9).

Most powerful earthquakes since 1900 (magnitude on the Richter scale): 1) Chile on May 22, 1960 (9.5); 2) off Sumatra, Indonesia on December 26, 2004 (9.3); 3) Prince William Sound in Alaska on March 28, 1964 (9.2); 4) Andreanof Islands, Alaska on March 9, 1957 (9.1); 5) Kamchatka Peninsula in eastern Russia on November 4, 1952 (9.0); 6) off the coast of Ecuador on January 31, 1906 (8.8); 7) Rat Islands, Alaska on February 4 1965 (8.7); 7) off Nias Island, Indonesia on March 28, 2005 (8.7); 9) Tibet on August 15, 1950 (8.6); 10) Kamchatka Peninsula in eastern Russia on February 3, 1923 (8.5); 10) Banda Sea, Indonesia on February 1st 1918 (8.5); 10) off Etorofu Island, northern territories, Japan (8.5.) [Source: U.S. Geological Survey]

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 +

1983 Sea of Japan Earthquake and Tsunami

A 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. +

TOKYO EARTHQUAKE OF 1923 ' See Separate Section

KOBE EARTHQUAKE OF 1995 ' See Separate Section

LARGE EARTHQUAKES IN JAPAN IN THE 2000s See Separate Section

Image Sources: J.B. Macelwane Archives, St. Louis University, USGS

Text Sources: New York Times, Washington Post, Los Angeles Times, Daily Yomiuri, Times of London, Japan National Tourist Organization (JNTO), National Geographic, The New Yorker, Time, Newsweek, Reuters, AP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.

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© 2009 Jeffrey Hays

Last updated January 2014

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