Seismic signals from tsunamis in the Pacific Ocean

Abstract

We examine seismic signals from tsunamis for 14 earthquakes of Mw 7.1 to 8.4 in the circum-Pacific region that generated tsunamis measured previously from tide gauges or coastal runup. Low-frequency signals of 0.5 mHz up to 2-8 mHz are observed at the expected tsunami arrival time on the horizontal components of low elevation seismic stations near coastlines for eight of the 14 earthquakes. Lower amplitude signals are observed for the other six. For two earthquakes (Mw 8.2-8.4) we observe a dispersed tsunami signal between 1 and 8 mHz, with lower frequencies arriving earlier. This dispersion is consistent with predictions from the standard model for gravity waves for the bathymetry along these source-station paths. These observations, along with earlier observations from the Indian Ocean, suggest that seismic data could be used to complement tide gauges and ocean bottom pressure recorders to indicate the arrival of a tsunami. Copyright 2008 by the American Geophysical Union.