Return to
Services to the Media
Return to
Starting Point
NEWS
For Immediate Release:
June 12, 1996
Contact: Dave Thomas
at (202) 777-7507
On June 15, 1896, nearly 22,000 Japanese lost their lives due to the most devastating tsunami in Japanese history. The tsunami, which was generated by an earthquake off the coast of Sanriku, Japan, attained a height of 25 meters (80 feet), and instantly swept away all houses and people when it reached land. The tsunami was also observed across the Pacific. In Hawaii, wharves were demolished and several houses were swept away. In California, a 9.5 feet wave was observed, according to the San Francisco Chronicle of June 16, 1896. This Sanriku tsunami served as an impetus for tsunami research in Japan.
It is well known that tsunamis are produced by undersea earthquakes. But, what is unusual about this century-old event is that the size of the tsunami is much larger than would be expected from the size of the earthquake, 7.2 on the Richter scale.
At the time of the Sanriku tsunami earthquake, a weak shock was felt, followed by an extremely slow shaking that lasted about 5 minutes. Approximately 35 minutes after the earthquake, the large tsunami arrived at the Sanriku coast.
One hundred years after the Sanriku tsunami, two researchers, Yuichiro Tanioka of the Department of Geological Science of the University of Michigan, Ann Arbor, and Kenji Satake of the Seismotectonics Section of the Geological Survey of Japan, Tsukuba, have developed a model using a modern computer simulation to describe the conditions that produced the unusual Sanriku tsunami.
The results of their research indicate that the source of the earthquake was very close to the Japan trench, unlike other earthquakes in the region whose sources are closer to the coast. They estimate that the fault that generated the earthquake had a width of 50 kilometers, and the movement along the fault was 5.7 meters.
The earthquake ruptured beneath an accretionary wedge, a relatively shallow area. If a substantial earthquake occurs in the same area in the future, a resulting tsunami could be unusually large, like the 1896 event.
Their findings will be published in the June 15 issue of Geophysical Research Letters produced by the American Geophysical Union.