On opportunity of short-term forecast for local tsunamis in the Kuril Islands

One of the problems of operational tsunami forecasting is a large (more than 75%) number of false alarms. According to modern ideas, tsunami warning services should declare not only reasonable general alarms, but also differentiated by the degree of danger for specific areas of the coast. A tsunami warning should be issued with a reasonable advance warning only at points where a tsunami poses a real threat, and should be accompanied by information on the arrival time of the first, maximum waves, their amplitudes, as well as the expected time of the end of the tsunami. Tsunami forecasting that meets these requirements is possible using tsunami information obtained in the open ocean from sea level measurement stations. In the case of local tsunamis, ocean level measurement stations located near the focus contain noise of seismic origin superimposed on the useful tsunami signal, which can make it difficult to obtain an adequate forecast.

The results of numerical simulation of the process of operational forecasting of local tsunamis of 2006 and 2007 on the Kuril Islands according to the data of the closest to the islands deep-ocean level station are presented. The computation was performed according to the station data complicated by seismic interference. The principal possibility of operational forecast of tsunamis arising at the Central Kuril Islands, according to the data of closest to the centers level station, even in the presence of seismic noise, is shown. Advance forecast for settlements of the Northern and Southern Kuril Islands is 0.5—1.5 hours, which ensures timely submission of alarm and evacuation of the population to safe places.

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