Observed water heights and calculated tsunami travel times, 11 March 2011
The 11 March 2011 M9.0 earthquake generated a devastating local tsunami that struck the Pacific coast of Honshu within about 20 minutes. The Japan National Police Agency reports 13,895 persons killed and 13,864 persons missing from the earthquake and tsunami. 141,343 residents are still staying at evacuation shelters. The 2011 Tohoku Earthquake Tsunami Joint Survey Group (http://www.coastal.jp/tsunami2011/) reports highest tsunami runup heights at Sendai in the 15-20 m range. The 11 March 2011 Japanese tsunami was the first to cause deaths since the 1993 Sea of Japan magnitude 7.7 earthquake caused 23 deaths and generated a tsunami that caused an additional 208, and the most fatal tsunami globally since the 2004 Indian Ocean tsunami generated off Sumatra, Indonesia that killed nearly 230,000 across the Indian Ocean.
The Japan Meteorological Agency’s national tsunami warning center issued a tsunami warning 3 minutes after the earthquake triggering the alerting process that immediately broadcasted by mass media and locally activated sirens and other mitigation countermeasures such as flood gate closures. Live video of the advancing tsunami waves and their impact on structures at the coast was aired by Japan NHK television and seen at the same time globally. Despite Japan’s sustained and globally-recognized excellence in tsunami preparedness, many casualties resulted and again reminded us of the swiftness and destructive power of tsunamis. Waves overtopped tsunami walls and destroyed many structures, especially wooden homes. Nonetheless, some tall reinforced concrete buildings and evacuation platforms did survive and allowed citizens to shelter in place by vertically evacuating. Tsunami waves also caused huge infrastructure damage to the Fukushima Nuclear Power Plant, resulting in the meltdown of core reactors and local emission of dangerous radiation. Like the previous tsunamis, drowning was the main cause of death, with casualties greatest in the elderly.
The tsunami also propagated across the entire Pacific Ocean, with runups up to 5 m and $8 million in damage to harbors and homes in Hawaii 7 hours later, up to 3 m and $20 million in damage in California 12 hours later, and up to 3 m heights and more than $4 million in damage 22 hours later in Chile. Outside of Japan, 1 person died in California, USA, and 1 person died in Papua, Indonesia.