Abstract
Large earthquakes, such as the Mw 7.7 1992 Nicaragua earthquake, have occurred off the Pacific coasts of El Salvador and Nicaragua in Central America and have generated distractive tsunamis along these coasts. It is necessary to determine appropriate fault models before large tsunamis hit the coast. In this study, first, fault parameters were estimated from the W-phase inversion, and then an appropriate fault model was determined from the fault parameters and scaling relationships with a depth dependent rigidity. The method was tested for four large earthquakes, the 1992 Nicaragua tsunami earthquake (Mw7.7), the 2001 El Salvador earthquake (Mw7.7), the 2004 El Astillero earthquake (Mw7.0), and the 2012 El Salvador–Nicaragua earthquake (Mw7.3), which occurred off El Salvador and Nicaragua in Central America. The tsunami numerical simulations were carried out from the determined fault models. We found that the observed tsunami heights, run-up heights, and inundation areas were reasonably well explained by the computed ones. Therefore, our method for tsunami early warning purpose should work to estimate a fault model which reproduces tsunami heights near the coast of El Salvador and Nicaragua due to large earthquakes in the subduction zone.
Highlights
The 1992 Nicaragua earthquake occurred off the Pacific coast of Central America and generated a much larger tsunami than expected from its surface wave magnitude of Ms 7.2; so the earthquake is classified as a ‘tsunami earthquake’ (Satake et al 1993)
We found that the solution is stable, so the seismic records observed at stations in the distances less than 30° can be used if a rapid response for tsunami early warning is needed
The fault parameters estimated from the W-phase inversion (Kanamori and Rivera 2008) and a scaling relationship (Blaser et al 2010) with a depth-dependent rigidity (Bilek and Lay 1999) are used to estimate the fault model for four large earthquakes which occurred off El Salvador and Nicaragua in Central America
Summary
The 1992 Nicaragua earthquake occurred off the Pacific coast of Central America and generated a much larger tsunami than expected from its surface wave magnitude of Ms 7.2; so the earthquake is. Gusman and Tanioka (2014) developed a method to estimate an appropriate source model for tsunami early warning using the results from W-phase inversions (Kanamori and Rivera 2008) of broadband seismograms. They applied their method to the 2011 Tohoku-oki tsunami and found that the observed tsunami run-up heights are well explained by the run-up heights numerically computed from the source model estimated by the W-phase inversion of the first 10 min of seismic waveform data. Those data are compared with those from a tsunami simulation to test our method
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