Disaster Mitigation Engineering -the Kobe Earthquake Disaster

The concept of plate tectonics is generally accepted in earth science and seismology. The surface of the earth is divided into rigid tectonic plates that move on the earth surface at extremely slow speed. The islands of Japan sit on the North American and Eurasian plates. The Pacific plate moves westward and the Philippines plate moves to northwest direction; both plates sink under the islands of Japan forming troughs along the boundaries. The strain energy is accumulated gradually by relative movement of adjacent tectonic plates and is suddenly released at the plate boundary in a form of an earthquake. Most of large magnitude earthquakes in Japan have taken place along the plate boundaries (plate boundary earthquakes). If we take one region along a boundary, an earthquake occurs once every one to two hundred years. This is almost a deterministic event for a human society, but the epicenter is normally further away from large cities.