The Earthquake Museum - Recent Quakes: March 2011

Updated 5/14/11
The east coast of Japan was hit by a 9.0 Magnitude earthquake on March 11,2011 at 05:46UTC (2:46 pm local time), that caused major damage in the northeastern part of the country. Severe shaking lasted over 2 1/2 minutes. The epicenter was undersea off the coast of Honshu, Japan's largest island, 230 miles northeast of Tokyo, 80 miles from the city of Sendai, which sustained the worst damage. Sendai is the largest city in the area, with over 1 million people. The northeastern prefectures of Miyagi, Iwate and Fukushima were the worst hit. Over 300 bodies were found along the coast in that city alone immediately after the tsunami. The final number killed is estimated at about 25,000. As of May 13, 2011 the official toll is 15,019 dead, 9056 missing two months after the quake,5,282 injured,88,873 houses damaged. 440,000 people were evacuated. Two months later 100,000 were still in shelters. Damage from the quake is expected to reach $230 billion. The Japanese economy will suffer from the disaster, but as reconstruction efforts, which could last 5 years, get underway it should provide a stimulus.

Strong shaking and some damage in Tokyo was dwarfed by the damage further north. Initial relief assistance was provided by the military. A Japanese relief team that had been helping after the quake in New Zealand was called home. International teams are offering their help in rescue efforts. The US military has many bases in Japan and has mobilized resources to help. Much of the initial rescue work was done with helicopters, since many roads were impassable and many areas were submerged in seas of mud and standing water left from the tsunami. Temperatures were near or below freezing at night in the days after the quake, with many left homeless. Then it got colder and started snowing. It took days for rescue crews to reach some areas. 380,000 were living in shelters in school gymnasiums with little heat due to fuel and electricity shortages and short rations food. People remained generally calm even under very difficult circumstances. It was difficult to get supplies into these areas and the government is overwhelmed. People are being urged to leave the northeast and go to other parts of Japan but with transportation systems inoperable and little available fuel, it is unclear how large numbers can be evacuated.

According to the USGS list of the largest earthquakes, this was the 4th largest earthquake in the world since 1900. A tsunami was generated that flooded coastal areas of Japan and caused tsunami warnings throughout the Pacific. Damage from the tsunami was extensive with 30 foot waves reaching sometimes as far as 6 miles inland. There was little warning, 15 to 30 minutes, for the areas nearest the epicenter. Many of the dead and missing are believed to be from the tsunami. News cameras show a wall of water, churning with mud and debris advancing inexorably over the land, swallowing everything in its path. Fishing boats, cars, lumber, even whole houses are caught up and carried along. Once caught in the fierce currents, it is almost impossible to escape. A giant whirlpool was filmed off the coast, that dwarfed a boat caught in it. Afterwards all that was left was mud, standing water and debris that is hardly recognizable as having been a city.

Although the destruction in the quake area is very bad, it will not rival the 2004 Indian Ocean tsunami for destructiveness. In that case, there were large populations living on the coast of the Indian Ocean, all of which were in range of the destructive tsunami waves. Tsunami warnings were sent throughout the Pacific and people in the Philippines, Indonesia and as far away as the west coast of the United States were evacuated from coastal areas. The tsunami waves in Hawaii were about 6 feet and caused some damage but no injuries. There was damage to boats in marinas in Santa Cruz and Crescent City, California and Seaside Oregon. One man in Crescent City was swept out to sea while he was photographing the waves at a beach during the second tsunami surge two hours after the first one hit. Crescent City was also hit hard, with 11 people killed, by the 1964 tsunami after the Anchorage, Alaska quake.

The Japanese transportation system was brought to a halt with buses and trains unable to operate. Four trains in the northeast are unaccounted for, with fears that they were swept away by the tsunami. A ship with 100 passengers was reported missing. Power was knocked out over large areas. Over 1 million people are without drinking water. Store shelves are bare as people bought what they could get and suppliers are unable to deliver more. Roads became impassable with large cracks from the quake or clogged with traffic as hundreds of thousands tried to leave the affected area. The government advised people to stay where after the quake they were if they were in a safe place. Large numbers of people were stranded in Tokyo and other cities unable to get home. many slept in shelters. Oil refineries caught fire, as were parts of the hardest hit cities. Under these circumstances, there is little that firefighters can do. Large areas of the city of Kesennuma, a city of 74,000 were burning. One third of that city was submerged. Iwate, with 23,000 people was largely destroyed. Whole villages have been reportedly washed away. Millions of people lost power and 4 days later 850,000 were still without electricity and 1.5 million still had no water.

Earthquakes are common in Japan, although this is the strongest one in recorded history there. Buildings are designed to sway, rather than collapse, with building codes reflecting the latest anti-quake techniques. The results of these efforts could be seen in Tokyo, where most buildings rode out the strong shaking without structural damage. An earthquake warning system gave a few precious seconds warning to many before the quake struck, allowing people to take cover. Two days after the quake, transportation was moving again in Tokyo and life was returning to normal. It will be a long time before the same can be said of the north.

Despite the severity of the quake, most of the deaths were from the tsunami. Building codes designed to protect against earthquakes worked very well despite the unprecedented size of this one. Many less powerful earthquakes have killed many times the number that died in this one because buildings were not built to resist them.

The scale of destruction from the tsunami was tremendous. The areas it hit were covered with mud and the debris of the cities that were inundated. One estimate said that the disaster produced a century worth of garbage. The government is struggling to figure out how to dispose of it all. There are many challenges including where to dump it all. New dump sites were established but they are filling up quickly. Nobody seems to be prepared to salvage ships that have been washed up on top of the debris of the cities. The clean up is expected to take years.

Five nuclear reactors at two power plants in Fukushima Prefecturate shut down automatically following the quake but the combination of the quake and tsunami cut off power needed to keep the cooling systems operating and disabled the backup diesel generators, which were located in the basement and flooded in the tsunami. A week after the quake, emergency crews may have a new power line in operation. This may help efforts to cool the stricken reactors. The worst hit plant is the Fukushima Daiichi plant, which has 6 reactors. They have all seen serious damage to their cooling systems. The scope and strength of this quake has strained the ability to recover. In the week following the quake there were hydrogen explosions at these plants and at least 2 fires. 170,000 people in a 12 mile radius around the Fukushima plants were evacuated. Those within 19 miles were advised to stay indoors. The US government advised Americans within 50 miles to leave the area if possible, or remain inside. The government attributes the explosions to hydrogen buildup in the cooling system and denies reports of a core meltdown. However, it has become apparent that parts of the reactor cores did melt. Radiation levels outside the plant are many times the normal background level, limiting the ability of workers to bring the reactors or spent fuel under control. the greatest danger is from spent fuel stored at the plant because it is not contained as well as the reactor core. Despite heroic efforts by plant workers radiation releases continued in the weeks following the quake. In the worst case scenario, there is a danger of a meltdown of fuel in any of these reactors that would release large amounts of radiation, as bad as, or worse than Chernobyl. Iodine tablets were distributed to those nearest the plants as a precaution to ameliorate the effects of larger radiation exposure, should that occur. Iodine taken before exposure can prevent the absorption of radioactive iodine, especially important for children. There has been a run on iodine pills worldwide amid fears of large scale radiation releases, despite government statements saying that this is not necessary for people far away. Workers were flooding the cores and spent fuel with sea water in a last ditch effort to cool it down. This has led to radioactive water leaking both within the plant and escaping into the sea. In all 11 of the 54 nuclear reactors in Japan have been shut down, leading to shortages of electricity, even in area that did not lose power. The accident is causing Japan to re-evaluate its heavy reliance on nuclear power. 30% of Japan's energy comes from nuclear. Power is being slowly restored to cities but smaller towns will have to wait longer. Some companies have curtailed production to conserve power. Foreign countries urged their citizens to leave Japan.

There have been frequent large aftershocks. In the 2 days following the quake there were over 85 quakes greater than 5.0 Magnitude, more than 20 over 6.0 M. After 4 days that number has climbed to over 100. Eyewitnesses reported quakes continuing so frequently that it seemed that they were continuous. These would all be considered large quakes capable of causing damage under any circumstances. The largest was 7.1 M. on March 11. The aftershocks continued, though not as frequently, for weeks. By April 7 there had been 136 aftershocks greater than 5.0 M. On April 7th there was another 7.1M aftershock. Even before the major quake there were foreshocks for a couple of days. On March 9, the same area was hit by a 7.1 M quake. This graphic animation shows the quake and aftershocks. The larger the circle, the larger the quake. It starts a few days before. Note the date and time at the bottom right.

The earthquake was the result of subduction of the Pacific Plate beneath the North American Plate. Japan is extremely prone to earthquakes because it is located at the intersection of four major tectonic plates, the Pacific Plate, The Eurasian Plate, The Phillipine Plate and the North American Plate. Despite its name, the North American Plate actually extends beyond Alaska north of the Pacific and into Siberia. An arm of the plate drops down to include northern Japan, sandwiched between the Pacific and the mainland of Asia, specifically the Russian Far East near Vladivostok, which is on the Eurasian Plate. Subduction quakes occur when plates, pieces of the earth's crust, collide, forcing one beneath the other. This type of quake has the potential to be among the largest earthquakes on earth. Generally, the continental plate will ride up over the oceanic plate in this situation. This earthquake resulted in the Japan's largest island of Honshu moving 8 feet to the east, overriding the floor of the Pacific Ocean. A large subduction quake will sometimes displace enough water when a large section of ocean floor suddenly slips under the over-riding plate to cause a tsunami. The size of the tsunami depends on the conditions at the epicenter and can be hard to predict. The destructiveness also depends on how close to populated areas the quake occurs. In this case there was large coastal populations nearby.

(See the Plate Tectonics page for a maps of the tectonic plates and more information on these processes.) The US Geological Survey (USGS) is an invaluable resource in understanding and tracking earthquakes. See the USGS summary of this quake.

See also the following news stories:

* Nuclear emergency declared at quake-damaged reactor (USA Today 3/11/2011)
* Japan evacuates 50,000 after nuclear power plant explosion (LA Times 3/12/2011)
* Google Resources Page on the Japanese Earthquake and Tsunami
* Quake clean-up continues as death toll grows (ABC Australia 3/18/11)
* Cable reaches Japan nuclear plant (BBC 3/17/2011)
* Pictures (BBC 3/11/2011)
* Japan devastated by 8.9-magnitude quake, tsunami (Washington Post 3/11/2011)
* 10K dead in Japan amid fears of nuclear meltdowns (Seattle Times 3/13/2011)
* Death toll rises, stocks plunge, foreigners flee as nuclear crisis escalates (Washington Post 3/15/2011)
* Factbox: Japan disaster in figure (Reuters 3/15/2011)
* Japan begins quake relief mission (BBC 3/11/2011)
* Japan damage could reach $235 billion, World Bank estimates (LA Times 3/21/2011)
* Strongest aftershock since tsunami rattles northeast Japan; 2 dead, widespread power outages (Washington Post 4/7/2011)
* Japan earthquake: Dealing with mountains of debris (BBC 5/14/2011)
*Listen to Japan's massive quake (The Lookout-A Y News Blog 3/18/2011)
* Sendai Tsunami through Western Eyes (Facebook)

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