Damage North of Sendai
Discover magazine reported: The magnitude 9 earthquake that shook Japan on March 11 dragged parts of the country 15 feet eastward and moved some seafloor transponders up to 230 feet, the largest earthquake-induced surface displacement ever recorded. Although Japan has the world’s most advanced earthquake-monitoring system, few researchers had expected a quake of such magnitude.[Source: Jennifer Barone, Discover, January-February 2012]

The first large tsunami waves struck the coast of northern Japan between 15 minutes and 30 minutes after the earthquake, with coastal areas closest to the quake epicenter being struck first. Waves as high as 12 meters surged onto shore, carrying away cars and boats, setting buildings ablaze and inundating factories, fields and highways. Towering lines of wave uprooted trees, rushed over sea walls trees, ripped down houses and pushed all the debris inland and then pull it back into the sea, leaving behind bits and pieces of this and that and layer of black mud. [Source: New York Times]

According to the Japan Meteorological Agency the height of the tsunami based on analysis of traces left on buildings and other structures: 33 meters in Minami-Sanriku, Miyagi Prefecture; 29.7 meters in Kamaishi, Iwater Prefecture; 21.5 meters in Tomioka, Fukushima Prefecture. Tsunami waves of over 30 meters high were recorded in places where 10-meter waves were pushed higher by narrow inlets and mountains close to the shore. In some of these places houses and even evacuation centers that were supposed to be safe because they were high off the ground were swept away. In other placed the waves swept inland for many kilometers. A total of 561 square kilometers was flooded. This included 62 cities, towns and villages in six prefectures. The figure is nine times the area inside Tokyo’s Yamanote loop line.

The tsunami that struck northern Japan was one of the largest ever recorded and far bigger than scientists thought possible because they did not anticipate such a large earthquake. Researchers at the University of Tokyo estimated that the tsunami wave that struck the Taro District of Miyako in Iwate Prefecture was 37.9 meters in height based on the drift displacement of the port and discovery of lumber from the port on the slope of a mountain 200 meters from the coast. Researchers also found fire engines and fishing boats on the mountain slope. The tsunami waves were so big they destroyed many tidal gauges used to measure wave size. [Source: Kyodo]

Television images showed waves and floodwaters, engorged with floating debris surging inland, pushing aside heavy trucks as if they were toys, depositing buses on four-story buildings ramming fighter jets into houses. Kyodo News reported a gigantic wave sweeping up a ship carrying more than 100 people. “The spectacle was all the more remarkable for being carried live on television,” the New York Times said, “even as the waves engulfed flat farmland that offered no resistance. The tsunami could be seen scooping up every vessel in the ocean off Sendai, and churning everything inland.” [New York Times]

Satellite images revealed how the coastline was changed during the tsunami. Amateur video captured boats being carried down city streets, water rushing through Sendai airport and masses of cars bobbing up and down like rubber ducks in cascades of black water. Shocked observers watched as the water carried away everything in its path.”The tsunami roared over embankments in Sendai city, washing cars, houses and farm equipment inland before reversing directions and carrying them out to sea,” Japanese engineer, Kit Miyamoto, said. “Flames shot from some of the houses, probably because of burst gas pipes.”

The tsunami lasted for two days, as its waves reached as far as Chile before reflecting back towards Japan . By the morning after the tsunami, Japan was filled with scenes of desperation, as stranded survivors called for help and rescuers searched for people buried in the rubble. Several coastal towns were literally wiped off the face of the earth.

Evan Osnos wrote in The New Yorker, “The afternoon of Friday, March 11th, was cool and partly cloudy on the northeast coast of Japan’s main island, a serene stretch once known as the nation’s “back roads.” At 2:46 P.M., as schools were beginning to let out, the ground began to shake. It was violent even by Japan’s standards — the thundering went on for five minutes — and before long Japanese television was warning of a wave charging west across the Pacific Ocean at the speed of a jet. Kicked up from the seabed, the tsunami amplified in size and slowed in speed as it moved into the shallows beside the Japanese coastline, and by the time it touched land it was a wall of water, black and smooth. It was as tall in places as a three-story building, moving at fifty miles per hour. [Source: Evan Osnos, The New Yorker, March 28, 2011]

“Unlike the Indian Ocean tsunami of 2004, the horrific grandeur of this moment unfolded before the unblinking eyes of Japan’s ubiquitous surveillance cameras, mobile phones, and hovering news helicopters, compiling a record of rebuke to the sense of protection once extended by the technology and engineering at the heart of Japanese life.” The tsunami “flicked fishing trawlers over seawalls, crunched them against bridges. It sent fleets of cars and trucks hurtling from parking lots, and turned homes into chips of wood and tile, before heading deeper into Miyagi and Iwate Prefectures across a span of six miles. Rampaging through former farming and fishing villages, and the cosmopolitan city of Sendai, the wave slowed, but remained too fast for most people to outrun on foot.

Tsunamis reached Tokyo but they were small. The first wave to reach Tokyo Bay was about 80 centimeters high. It arrived at 4:40pm about an hour and 45 minutes after the earthquake. The highest was 1.5 meters and came at 7:16 p.m.

Links to Articles in this Website About the 2011 Tsunami and Earthquake: 2011 EAST JAPAN EARTHQUAKE AND TSUNAMI: DEATH TOLL, GEOLOGY Factsanddetails.com/Japan ; ACCOUNTS OF THE 2011 EARTHQUAKE Factsanddetails.com/Japan ; DAMAGE FROM 2011 EARTHQUAKE AND TSUNAMI Factsanddetails.com/Japan ; EYEWITNESS ACCOUNTS AND SURVIVOR STORIES Factsanddetails.com/Japan ; TSUNAMI WIPES OUT MINAMISANRIKU Factsanddetails.com/Japan ; SURVIVORS OF THE 2011 TSUNAMI Factsanddetails.com/Japan ; DEAD AND MISSING FROM THE 2011 TSUNAMI Factsanddetails.com/Japan ; CRISIS AT THE FUKUSHIMA NUCLEAR POWER PLANT Factsanddetails.com/Japan

40.4 Meter Tsunami Waves

A 40.4 meter tsunami — the largest on record — struck the Omoeaneyoshi district of Miyako, Iwate Prefecture after the March 2011 earthquake, according to a national joint survey conducted by about 150 researchers from 48 research organizations who presented their findings at a meeting held in Osaka in July. [Source: Yomiuri Shimbun, July 18, 2011]

Data was collected from 5,400 locations from Hokkaido to Okinawa Prefecture. The researchers surveyed the runup height of tsunami from the traces of waves left on building walls or trees, and compared the data with observation data compiled by the central and local governments.

A survey conducted in April found that Omoeaneyoshi was hit by a tsunami measuring 38.9 meters during the March 11 disaster, beating the 38.2-meter record set in 1896 when the area was hit by the Meiji Sanriku Earthquake. But the latest survey has revealed the March 11 tsunami reached a massive 40.4 meters elsewhere in the district.

Places Hits by Previous Tsunamis

In July 2011, Kyodo reported at least 21 of the dozens of communities in northeastern Japan whose residents had moved to higher ground after being swamped by massive tsunamis in the past were flooded by the March 11 tsunami. Yoshiaki Kawata, a Kansai University professor who heads the expert panel of the government's Central Disaster Prevention Council, pointed out the necessity of moving to higher elevations. According to his analysis, most of the 21 communities in Iwate and Miyagi prefectures hit by the recent tsunami were only around 10 meters above sea level. [Source: Kyodo, July 10, 2011]

"Elevations should be sought based on the biggest possible scale (of tsunami). If people compromise and opt to settle in areas close to what used to be urban areas, it could lead to damage on a large scale," Kawata said.

According to the Cabinet Office, residents in 43 communities moved to higher ground -- either collectively or individually -- after massive tsunamis triggered by the 1896 Meiji-Sanriku Earthquake, while those in 98 communities, including some of the 43, moved higher after the 1933 Sanriku Earthquake. Following the 1960 Chilean Earthquake, one community found that the ground it was located on had been thrust up to a higher elevation.

The office has found in its study that of those communities, at least 21 also suffered damage from the March 11 disaster, including a district in the town of Otsuchi, Iwate Prefecture. Only nine communities that moved higher were spared the devastation caused by the recent tsunami waves, including one that now forms a part of the city of Ishinomaki, Miyagi Prefecture. Kawata noted that the local communities ravaged by the March 11 tsunami may face difficulties in forming the consensus needed if they are to move collectively to a higher location. Even if some communities do relocate higher, some residents may move back to down again, placing priority on living closer to where they work, he said.

Force and Power of the Tsunami of 2011

20110413-Miayako US Marines 22.jpg
Damage in Miyako
The 9.0-magnitude earthquake off the coast of northern Honshu produced a devastating tsunami that sent walls of water washing over coastal cities in the north. In a rough guess, Harry Yeh, a professor of ocean engineering at Oregon State University, told the New York Times that the earthquake pushed a section of sea floor 250 miles long and 50 miles down by an average of one yard. That resulted in billions of cubic yards of water — trillions of pounds — suddenly shifting position. That energy going into the tsunami, according to Professor Yeh’s estimate, was a bit less than that of an exploding atomic bomb. [Source: New York Times]

Yomiuri Shimbun reported, “A giant rock called Tsunami-ishi (tsunami rock) sits in a field in Miyako, Iwate Prefecture, illustrating the power of the Great East Japan Earthquake and tsunami, which moved the rock 470 meters. A team of researchers from the Chiba Institute of Technology and Tsukuba University found the rock, which measured a maximum of 6.5 meters wide and 2.4 meters high, while researching tsunami-affected land features in coastal areas of the Sanriku region in late August. After studying aerial photographs and interviewing residents, researchers found that the rock, which weighs an estimated 140 tons, was displaced from near a breakwater. Kazuhisa Goto, chief researcher at the Chiba Institute, said the researchers will use the rock to analyze how powerful the tsunami was. [Source: Yomiuri Shimbun, December 3, 2011]

On the force of the water generated by tsunamis the New York Times reported: “A typical bathtub holds 40 gallons or so of water. That is 330 pounds. A cubic yard of it, filling what at first glance seems a modest volume of 3 feet by 3 feet by 3 feet, weighs nearly 1,700 pounds, as much as the Smart micro car. And when water is moving at 30 or 40 miles an hour, like the tsunami that inundated northern Japan on Friday, the heaviness of water turns deadly. Imagine 1,700 pounds hitting you at that speed, and each cubic yard of water as another 1,700 pounds bearing down on you. The destructiveness of a tsunami is not just one runaway car, but a fleet of them. [Source: New York Times]

“That’s exactly the analogy to use,” Philip N. Froelich, a professor of oceanography at Florida State University, told the New York Times. “And by the time you’re talking about a wall of water that’s 10 meters high, if that wave is two miles long into the ocean, it’s basically like a hundred tanks coming across you. Even though it’s a fluid, it operates like a solid hammer.”

“Water does not act quite the same way as speeding cars,” the New York Times reported. “As a fluid, it can slip around some objects like round columns, while slamming full force when a large wall is in its way. It also gathers debris — dirt, cars, trees — as it flows. Those added projectiles can create more destruction as they crash into other objects. Even if the wave only comes up to the knees, the force is enough to knock a person down.”

Tsunami waves not only struck Japan they also spread across the Pacific. Hawaii was hit by seven-foot waves that caused little damage. Powerful surges that struck the West Coast of the United States caused boats to sink in Santa Cruz Harbor. The Coast Guard reported that one person was swept to sea near McKinleyville, Calif., while trying to take pictures of the waves. In Chile, where scientists said the thrust of the tsunami crossing the Pacific was headed, ports were closed and 700,000 people were evacuated from coastal communities. As on the U.S. West Coast, the damage was far lighter than feared.

Tsunami Hits America and Causes Massive Icebergs to Break Off in Antarctica

Tsunami waves almost three meters high reached the California coast. “Taro Nishijima wrote in Yomiuri Shimbun, “The first waves of the tsunami reached Crescent City's coast on the morning of March 11, 2011, about 10 hours after the Great East Japan Earthquake struck. The maximum height of the waves reached 2.5 meters. The waves ravaged the harbor repeatedly, causing 16 fishing boats to sink and damaging an additional 60 boats. At the time, there were about 85 fishing boats registered at the harbor. Almost all the boats were damaged, except those that were not moored there. Harbor restoration work, such as salvaging sunken ships and repairing piers, cost a total of $32 million dollars — a heavy financial burden for a small city with a population of about 7,500. [Source: Taro Nishijima, Yomiuri Shimbun, March 16, 2012]

The tsunami was so big it produced a wave that radiated throughout the rest of the world’s oceans. And according to research published online in the Journal of Glaciology, it caused massive chunks of ice with a combined surface area about twice that of Manhattan to break off from an ice shelf on the coast of Antarctica. [Source: Joanna M. Foster, New York Times, September 2011]

Joanna M. Foster wrote on the New York Times website, “While it has long been suspected that seismic activity of this magnitude could affect ice shelves — Charles Darwin thought as much about icebergs he observed in a fjord in Chile after an earthquake — this is the first time that scientists have been able to use satellite imagery to document the phenomenon as it occurred. Eighteen hours after the earthquake struck, waves began hitting the Sulzberger Ice Shelf, more than 8,000 miles south of the quake’s epicenter.”

the largest iceberg was 9.5 kilometers by 6.5 kilometers, making it slightly bigger in surface area than Manhattan, and had a a liley depth of 80 meters. “In the article, by the NASA scientist Kelly Brunt and her fellow researchers Douglas MacAyeal of the University of Chicago and Emile Okal of Northwestern University, the waves were little more than a foot high when they reached Antarctica. Still, they succeeded in breaking off more than 50 square miles of ice from the shelf. More than 260 feet thick, the Sulzberger Ice Shelf had been stable for decades, since the first satellite images were recorded in the 1960s.”

Dr. MacAyeal told the New York Times soldiers walking across a bridge offer an analogy for the phenomenon: they have to break step so as not to run the risk of collapsing it. “It’s the same principle here,” he said. “Vibrations on the ocean surface caused by the tsunami came into Antarctica and vibrated the surface of the ice at just the resonance frequency, and it just broke.”

One factor that scientists believe may have contributed to the birth of these giant new icebergs is the decline of sea ice in the Antarctic Ocean that acts as a natural buffer. In 2004, when protective sea ice was more abundant, a tsunami on the Indonesian island of Sumatra did not lead to any observed iceberg calving. “It’s a powerful reminder that these ice shelves are not as isolated as they seem,” Dr. MacAyeal said. “They’re able to feel events that happen thousands of miles away; sobering connections exist between different earth systems.”

March 2011 Earthquake Shook Satellites Out of Their Orbits

In December 2011, The New Scientist reported that Tohoku earthquake produced shock waves powerful enough to knock satellites out of their orbits. Two affected satellites — part of a research project called GRACE (Gravity Recovery and Climate Experiment) — follow similar orbits about 136 miles apart, while taking ultra accurate readings of the distance between them, and any changes in the surrounding magnetic field. Following the March earthquake, these variations grew to double their normal level as the satellites passed over the earthquake zone.

Anil Ananthaswamy wrote on New Scientist website, “The Tohoku earthquake that rattled Japan on 11 March changed Earth's gravitational field enough to affect the orbits of satellites. The satellites' altered courses suggest that the earthquake was stronger and deeper than instruments on Earth indicated. [Source: Anil Ananthaswamy, New Scientist, December 7, 2011]

These weren't just any satellites: they are the twin spacecraft of the Gravity Recovery and Climate Experiment (GRACE), which fly 220 kilometres apart in a polar orbit about 500 kilometres above Earth. GRACE's job is to map the Earth's gravity field, and it does this by monitoring the effect of minute variations in the field on the trajectories of the satellites and the changing distance between them.

Earth's gravity field changes whenever there is a redistribution of mass on its surface. This may be a result of snowfall, flood, melting of ice caps — or earthquakes. "That perturbed gravitational field affects the satellite orbits," explains Shin-Chan Han of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

The researchers calculated how the relative velocity of the two satellites changed as they passed over the affected region. GRACE records variations in the gravity field due to other processes too, but these background signals change over larger time scales than that of the quake, and so could be identified and subtracted.

NASA and the German Space Agency DLR who jointly operate the GRACE program, now feel that this discovery will lead to a more accurate way to measure the magnitude of large earthquakes.

Tsunami Overlap Increased Damage

The Yomiuri Shimbun reported: “The multiple tsunami caused by Friday's Tohoku Pacific Offshore Earthquake wreaked enormous destruction not only because of the quake's massive energy and proximity but also because they hit coastal areas from various angles and overlapped, experts said. As the fault rupture was 500 kilometers long in a north-south direction, "tidal waves hit the coastal area from different directions and crossed over each other, increasing [the tsunami's] destructive power," said Tomoya Shibayama, professor of ocean engineering at Waseda University. "They also became higher after currents threw them back and forth against the sea floor in coastal areas where the water was more shallow." [Source: Yomiuri Shimbun. March 14, 2011]

According to Prof. Shibayama, a massive tidal wave would become turbulent and develop more power once reaching inland areas... Damage this time was catastrophic because the latest tsunamis were higher and faster than expected. If a tsunami was four meters high, its approaching speed would have been 21 kilometers per hour, experts said. The tsunami apparently swept residential areas from more than one direction as some breached the breakwaters while others flowed up rivers after reaching the coast.

In the Ryoishicho district of Kamaishi, Iwate Prefecture an 18-meter-high tsunami flooded an area as far as one kilometer inland. It carried light materials like wood to a hillside, left relatively heavy debris closer to the sea, and deposited the heaviest items, such as concrete blocks and metal, near the shoreline.[Source: Atsuki Kira and Akiko Yoshinaga, Yomiuri Shimbun, May 10 2011]

Jagged Coasts Intensified Tsunami Waves and Made Them More Deadly

In December 2011, the Yomiuri Shimbun reported: “A high percentage of the people still missing in Miyagi Prefecture as a result of the March 11 tsunami lived along the Sanriku coastline, suggesting the area's unique ria structure accelerated the deadly waves. According to the prefectural government, the ratio of people still missing among the total dead and missing in five municipalities along the coastline is five times that of eight municipalities on the Sendai plains. [Source: Yomiuri Shimbun, December 23, 2011]

A ria formation consists of many long, narrow coastal inlets, and experts believe that the people still missing after March 11 were pulled into the ocean by the strong force of receding waves, which was exacerbated by the ria structures. A total of 8,144 people died or went missing in five Miyagi Prefecture municipalities located on the Sanriku coastline--Ishinomaki, Kesennuma, Higashi-Matsushima, Onagawacho and Minami-Sanrikucho--according to December 2011 figures.

At least 1,877 residents from Miyagi Prefecture remain missing and almost all of them--1,746 people--were living in the five coastline municipalities. These people account for 21.4 percent of those who were killed or went missing in this area. In an extreme case, figures released by the Ishinomaki city government show that of the 236 residents listed as dead or missing in its Ogatsu district, 97 people, or about 41 percent, were still missing as of Nov. 30. The district lies on a particularly indented section of Ogatsu Bay's ria coastline.

In contrast to the high number of people still unaccounted for along the ria coastlines, missing people make up only 4 percent of those killed and missing in eight inland municipalities located on Miyagi Prefecture's Sendai plains. Sendai, Natori, Shiogama, Iwanuma, Shichigahamamachi, Rifucho, Wataricho and Yamamotocho were hit by similar tsunami waves, but only 122 people remained missing as of December 2011.

"If a tsunami reaches a narrow bay along an extremely indented ria coastline, its force will intensify and its receding power will not wane," said Prof. Fumihiko Imamura at Tohoku University, an expert in tsunami engineering. "It's highly possible that many of those who remain missing were brought back to the ocean by tsunami's strong receding force after they had once been brought inland," he said.

Traditional Japanese Building That Survived the Full Force of the Tsunami

In Ishinomaki, Miyagi Prefecture a century-old storehouse somehow survived the March 2011 tsunami, will be preserved with the support of building experts and enthusiasts across the country. The two-story storehouse, which was built in the year following the 1896 Meiji Sanriku Earthquake, is in the Kadonowaki district, about 500 meters from Ishinomaki Bay. The structure's characteristic feature is its namako kabe-style outer walls, which are covered with square tiles with joints protected by plaster. [Source: Yomiuri Shimbun, October 26, 2011]

According to its owner Eiichi Honma, 62, the tsunami washed away Honma's house and another storehouse on his land. The storehouse that survived had part of its outer wall damaged by destroyed houses and cars carried by the tsunami, and its first floor was flooded. However, it withstood the disaster relatively well, probably thanks to repairs to the reinforcement bars of the outer wall last year.

Lessons From the Great Japanese Quake and Tsunami

Discover asked Earth scientists and disaster-preparedness experts about the top lessons from the Great East Japan Earthquake. Here is what they said: 1) Take the very long view. Models of earthquake risk in Japan were based on a 400-year historical record, but paleoseismic records suggest quakes of this size occur in the country’s Tohoku region every thousand years or so. “If your thinking is based on the last few hundred years, and you haven’t captured a representative time frame for that system, you’re going to be surprised,” says Mark Simons, a geophysicist at Caltech who studied the dynamics of the quake. [Source: Jennifer Barone, Discover, January-February 2012]

2) Watch the seafloor. Japan’s earthquake-monitoring network includes 1,200 GPS sensors that track the deformation of the Earth’s crust to help researchers measure and locate the buildup of seismic strain, but these devices do not work underwater. This is a serious limitation: Like 90 percent of all earthquakes greater than magnitude 8, Japan’s temblor happened at sea. Studying movement of the ocean floor currently requires installing acoustic transponders on the bottom and sending a research vessel out to ping them, which can cost half a million dollars per data point. “Land-based measurements have been the cheap answer,” says Georgia Tech geophysicist Andrew Newman, “but a buoy with a GPS and satellite communications could take the place of a ship and help us get more frequent seafloor measurements more affordably.” advertisement | article continues below

3) Faults break in complex ways. Earthquake risk assessments in Japan focused on a model that divided the fault into six segments, examining scenarios in which one or two of the segments ruptured at once. In fact, five fault segments failed simultaneously, producing a quake much larger than the model had predicted. Seismologist Mark Petersen, who leads the USGS project mapping seismic risk in the United States, says that the agency is now updating its models of major faults in the Western United States based on the events in Japan.

4) Building codes work — for earthquakes. The disaster showcased the power of strong, well-enforced building codes to defend against megaquakes. “Japan has some of the best codes in the world, and they performed very well,” says FEMA geophysicist Michael Mahoney. Most inland buildings that collapsed were built before regulations adopted in the 1970s required more reinforcing steel in concrete structures. Newer buildings suffered damage but remained standing. Engineering against a tsunami, on the other hand, is very difficult. Thirty-foot waves overwhelmed the nation’s seawalls and swept away entire towns. For now, the only practical defense against that, Mahoney says, is training coastal residents to head for high ground when they feel violent shaking.

One-Meter-High Tsunami Hits Japan after 7.3 Earthquake in December 2012

In early December 2012, a 7.4-magnitude earthquake struck off Japan's northeastern coast, temporarily triggering some tsunami waves that reached a meter in height but didn’t cause any destruction. One person was reported missing and 11 people were injured due to the quake. Erica Hill reported on NBC News: “Tsunami waves up to 3 feet high hit the coast of Japan Friday, after a strong earthquake in the sea that shook buildings 300 miles away in Tokyo. The temblor struck at 5:18 p.m. local time (3:18 a.m. ET), according to the U.S. Geological Survey. [Source: Erica Hill, NBC News, December 7, 2012]

The earthquake hit in the same area as the devastating quake and tsunami in March last year that killed nearly 20,000 people and triggered the world's worst nuclear crisis in 25 years. Friday's quake struck about 200 miles southeast of Kamaishi, the USGS said. The epicenter was 6.2 miles beneath the seabed, according to the Japan Meteorological Agency. Buildings in Tokyo swayed for at least several minutes, but there were no early reports of damage or injuries.

NHK television broke off regular programming to warn that a strong quake was due to hit shortly before the impact was felt. Afterward, the announcer repeatedly urged all near the coast to flee to higher ground. The quake triggered a tsunami warning for the Miyagi Prefecture, which was at the center of the 2011 disaster. It also sparked tsunami advisories for Pacific Coast areas of several other prefectures. But by 5:20 a.m. ET, two hours after the quake, the Japan Meteorological Agency had canceled all tsunami advisories and warnings.

Still, a batch of tsunami waves, measuring about 3 feet tall, hit the town of Ishinomaki, in Miyagi Prefecture, about an hour after the earthquake, according to Japanese television. Another tsunami wave, measuring about a foot tall, was detected at Ofunato. "I was in the center of the city the very moment the earthquake struck. I immediately jumped into the car and started running away towards the mountains. I'm still hiding inside the car," Ishinomaki resident Chikako Iwai told Reuters. "I have the radio on and they say the cars are still stuck in the traffic. I'm planning to stay here for the next couple of hours," Iwai said. A 6.2-magnitude aftershock struck at about 3:31 a.m. ET, but no damage or injuries were immediately reported.

Kyodo reported: “All but two of Japan's nuclear plants were shut down for checks. Tokyo Electric Power, the operator of the Fukushima nuclear plant, reported no irregularities at its nuclear plants after quake. Prime Minister Yoshihiko Noda canceled campaigning in Tokyo ahead of a Dec. 16 election and was on his way back to his office, but there was no immediate plan to hold a special cabinet meeting. [Source: Kyodo, December 8, 2012]

The Yomiuri Shimbun reported: “The earthquake that occurred off the Sanriku coast in the Tohoku region was a so-called outer-rise earthquake, which occurs on an ocean plate before the point where the plate is subducted under a continental plate. One characteristic of outer-rise earthquakes is the potential for large tsunami because the plate moves vertically in shallow water. The focus of Friday's earthquake was about 240 kilometers from the Oshika Peninsula in Miyagi Prefecture and about 10 kilometers deep. It is east of the focal area of last year's magnitude-9.0 Great East Japan Earthquake. [Source: Yomiuri Shimbun, December 9, 2012]

The Meteorological Agency called it an aftershock of the Great East Japan Earthquake. "A fault shift occurred because the Great East Japan Earthquake released a 'stopper' of the ocean plate, causing subduction stress to increase," said Akira Nagai, chief of the agency's earthquake and tsunami observation division at a press conference. Tohoku University Prof. Fumihiko Imamura, who specializes in tsunami engineering, said, "Outer-rise earthquakes are likely off the Sanriku coast and we need to stay vigilant [against a possible outer-rise earthquake] in the future.”

Reaction to the December 2012 Quake

On how people in the area of of the December 2012 earthquake reacted, The Yomiuri Shimbun reported: “Many residents in areas affected by the March 2011 earthquake quickly evacuated after a strong temblor shook the Tohoku and Kanto regions. Although damage from the quake was limited, it revealed problems regarding the dissemination of information and means of evacuation people opt for when an earthquake strikes. [Source: Yomiuri Shimbun, December 9, 2012]

In Iwaki, Fukushima Prefecture, a tsunami warning was issued at 5:22 p.m. Friday. Six minutes later, municipal employees sent "area mail" to mobile phones to inform them of information about a possible tsunami. Although the municipal government did not issue an evacuation order, about 200 residents in the coastal areas of the city voluntarily headed to evacuation sites such as primary and middle schools.

The evacuation sites were identified on a tsunami hazard map compiled by the local government in August after discussions with residents. In some areas, residents conducted evacuation drills on the assumption a huge tsunami would hit. An official at the municipal government's crisis management division said, "With the hazard map and evacuation drills, the reaction of evacuating to higher ground in the event of long, strong quakes is taking root.”

In Kamaishi, Iwate Prefecture, the community wireless system for automatically broadcasting messages from J-Alert, a nationwide warning system sent via radio waves, did not work properly. A local government official verbally broadcast the information about three minutes later. In some areas, people could not hear the announcement, according to the local government. In Natori, Miyagi Prefecture, the municipal government tried to inform people that a tsunami warning had been issued via sirens set up at three locations after last year's disaster, but they did not work. An local government official in charge of the measures said: "We've refrained from regularly testing the sirens so as not to annoy people living nearby. We'll consider checking them periodically with understanding from residents.”

After the quake, roads from coastal areas in cities including Ishinomaki and Natori in the prefecture became jammed with motorists. National roads in Kamaishi also became jammed following the quake. An official at the municipal government's disaster-prevention crisis management division said: "We've informed people not to evacuate by vehicle based on lessons learned last year, but the message didn't get across. We'll review the measures.”

Kwansei Gakuin University Prof. Yoshiteru Murosaki, an expert in disaster-prevention planning, said: "As far as I know through the media, the evacuation went as smoothly as it could have, with people evacuated in an orderly manner with their families and communities in darkness." He also urged people to keep in mind that evacuation is not a waste of time even if it turns out not to have been necessary. "This time around, people's memories of last year's disaster were still clear. However, over time they might come to believe there's no need to evacuate," he said. Regarding traffic jams, Murosaki said, "[The local government] should familiarize people with the idea that they should evacuate on foot.”

Image Sources: 1) U.S. Navy; 2) United States Geological Survey USGS); 3) National Oceanic and Atmospheric Administration (NOAA); 4) NASA; 5) U.S. Marines

Text Sources: New York Times, Yomiuri Shimbun, Daily Yomiuri, Washington Post, Los Angeles Times, Kyodo News, National Geographic, The Guardian. Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, and various books and other publications.

Last updated January 2013

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