JAPAN: Earthquake and Tsunami 2011

On March 11, 2011, an earthquake of 8.9. magnitude struck off the coast of Japan, the strongest ever recorded in the country. The quake churned up a devastating tsunami that swept over cities and farmland in the northern part of the country and set off warnings as far away the west coast of the United States and South America.The next day, Japanese news media estimates of the death toll ranged between 1,300 and 1,700, but the total could well rise. Many communities were scrambling to find the missing; in the port town of Minamisanriku, nearly 10,000 people were still unaccounted for. More than 300,000 people have been evacuated.Japan mounted a nationwide rescue effort to pluck survivors from collapsed buildings and rush food and water to thousands in an earthquake and tsunami zone under siege, without water, electricity, heat or telephone service. Severe aftershocks continued to rock a traumatized country.Nuclear Emergency: An explosion at a nuclear power plant in northern Japan on March 12 blew the roof off one building and destroyed the exterior walls of a crippled reactor, escalating the "atomic emergency'' that had been declared the day before.Officials that leaks of radioactive material from the plant, which began before the explosion, were receding and that a major meltdown was not imminent. But severe problems at two nuclear plants close to the epicenter of the quake forced evacuations of tens of thousands of people from surrounding areas, hampering efforts to search for survivors and forcing Japan’s leadership to grapple with two major crises as the same time.U.S. Offers Help: Several ships from the United States Navy joined the rescue effort. The McCampbell and the Curtis Wilbur, both destroyers, prepared to move into position off Miyagi Prefecture to assist Japanese forces with search and rescue efforts. In addition, the Ronald Reagan Carrier Strike Group was en route and was expected to arrive on March 13. The ship can serve as a floating platform for refueling helicopters from the Japanese Self-Defense Forces working more closely to shore. Japan was also accepting offers of help from other countries.Nature of the Quake: The quake occurred in what is called a subduction zone, where one of the Earth’s tectonic plates is sliding beneath another. In this case, the Pacific plate is sliding beneath the North American at a rate of about 3 inches a year. The earthquake occurred at a depth of about 15 miles, which while relatively shallow by global standards is about normal for quakes in this zone, said Emily So, an engineer with the United States Geological Survey in Golden, Colo.Ms. So said that according to her agency’s calculations, the quake was of magnitude 8.9. It had been preceded by what seismologists call foreshocks — smaller quakes in the same area. The largest of these was a magnitude 7.2 quake two days before, centered about 25 miles south of the spot where the earthquake struck Friday.In a subduction quake that occurs underwater, as this one did, the sudden movement of a portion of one of the plates can displace enormous amounts of water, triggering a tsunami. As the tsunami waves approach shallow coastal areas, they tend to increase in height.The quake was less powerful than the 9.1-magnitude quake that struck off Northern Sumatra in late 2004. That quake spawned a tsunami that killed more than 200,000 people around the Indian Ocean.Japan's Preparations: From seawalls that line stretches of coastline, to skyscrapers that sway to absorb earthquakes, to building codes that are among the world’s most rigorous, no country may be better prepared to withstand earthquakes than Japan. Had any other populous country suffered the 8.9 magnitude earthquake, tens of thousands of people might already be counted among the dead.(Source: http://topics.nytimes.com/top/news/international/countriesandterritories/japan/index.html)