ИСТИНА

Offshore observations make it possible to detect tsunamis in advance prior to their arrivals at the shoreline. For this purpose, ocean bottom pressure gauges are traditionally used. However, in near- and intermediate fields, ocean bottom pressure records usually exhibit a complicated interference of signals related not only to gravitational, but also to hydroacoustic and seismic waves. Network of offshore observatories recently developed and deployed in Japan provide high sampling records of ocean bottom pressure and seismic (acceleration and velocity) signals. In the present study, by taking advantage of simultaneous measurements of pressure and seismic signals that were recorded during some recent tsunamigenic earthquakes, we reveal particular features of these signals and develop a practical method for selecting a tsunami signal from ocean bottom pressure records.