On March 11, 2011, a magnitude Mw9.0 earthquake occurred near the east coast of Honshu, Japan, at 13：46 （Beijing time）, with an epicenter at 38.321°N, 142.369°E and a source depth of 24 km, as determined by the United States Geological Survey （USGS） （http：//earthquake.usgs.gov/ earthquakes/eqinthenews/）. A great tsunami then battered the northeast coast of Japan after the earthquake. The wave reached a maximum height of 23.6 m in some areas （http：//news.sina.com.cn/w/2011-03-24/082322172726.shtml）. The earthquake also resulted in damage to a nuclear power plant in Fukushima that generated nuclear leakage. The earthquake, tsunami and nuclear leakage have brought about huge economic losses and casualties.
