The 2011 Great East Japan Earthquake Disaster

Abstract

The 2011 Tohoku earthquake (magnitude 9.0), the largest earthquake in Japanese history, resulted in devastating tsunami damage and the partial destruction of the Fukushima Dai-ichi nuclear power station. Extensive seafloor displacement and slip on the shallow plate interface of the Pacific Plate near the Japan Trench axis have been revealed from the land-based GPS network and marine geodetic observation systems. The generation and propagation of the tsunami were also recorded on offshore bottom pressure and GPS wave gauges, prior to its arrival at the coast. Long-term earthquake forecasts, based on the recurrence of past large earthquakes, failed to foresee this giant earthquake. However, in retrospect, the historical record and recent paleoseismological studies indicate that tsunamis with similar characteristics occurred on the Sanriku coast in 1896 and on the Sendai plain in 869. Analysis of the 2011 tsunami waveforms clarifies that the tsunami source was a combination of the 1896-type “tsunami earthquake” and the 869-type earthquake on the deeper plate interface.