Simulations of tsunami propagation and tsunami inundation, and W phase inversion analysis were carried out for earthquakes with magnitudes Mw > 7.0 since 1990 up to now on the Pacific and Caribbean coasts of Nicaragua. The National Tsunami Warning System in Nicaragua was developed step by step after the Nicaragua tsunami earthquake Mw=7.7 occurred on September 2, 1992. At the time of the earthquake, there was no seismic network and monitoring system in real-time, and therefore, it has been essential to strengthen tsunami warning system in this region. We introduced the W phase inversion method, in which global data of very low-frequency broadband seismic records from IRIS-DMC were used. The seismic records at stations located at a distance range within 30 degree, were enough for obtaining a good and stable moment tensor solution and an accurate magnitude for tsunami warning purpose.
In the simulations of tsunami propagation and inundation, we used three seismic source parameters (W phase CMT, GCMT and PDE), and assumed two different fault models. For model 1 (ST1), we fixed the rigidity of 33.0 GPa to estimate the slip amount and also fixed the top depth of the fault to be 10.0 km. The length and width of the fault were calculated using a scaling’s law. For model 2 (ST2), we estimated a slip amount assuming that the rigidity increases with the depth and we estimated the depth of the fault. For the bathymetry data, GEBCO 30 arc-seconds and one arc-minutes of grid spacing were used. The tsunami simulation results from model 2 (ST2) showed good agreements with the observed tsunami data in most of the cases. The technique we developed in this study will be used to update the tsunami warning in INETER, Nicaragua.
Keywords: W phase inversion, Moment tensor solution, Tsunami simulation.