Abstract
Abstract. Despite the occurrence of several large earthquakes during the last decade, Chile continues to have a great tsunamigenic potential. This arises as a consequence of the large amount of strain accumulated along a subduction zone that runs parallel to its long coast, and a distance from the trench to the coast of no more than 100 km. These conditions make it difficult to implement real-time tsunami forecasting. Chile issues local tsunami warnings based on preliminary estimations of the hypocenter location and magnitude of the seismic sources, combined with a database of pre-computed tsunami scenarios. Finite fault modeling, however, does not provide an estimation of the slip distribution before the first tsunami wave arrival, so all pre-computed tsunami scenarios assume a uniform slip distribution. We implemented a processing scheme that minimizes this time gap by assuming an elliptical slip distribution, thereby not having to wait for the more time-consuming finite fault model computations.We then solve the linear shallow water equations to obtain a rapid estimation of the run-up distribution in the near field. Our results show that, at a certain water depth, our linear method captures most of the complexity of the run-up heights in terms of shape and amplitude when compared with a fully nonlinear tsunami model. In addition, we can estimate the run-up distribution in quasi-real-time as soon as the results of seismic finite fault modeling become available.
Highlights
Countries exposed to coastal inundation have done a lot of work to develop their tsunami warning systems (Doi, 2003; Wächter et al, 2012)
The W-phase method is preferred for accounting for large earthquakes in Chile, which provides a first moment tensor solution within 5 min (Riquelme et al, 2016, 2018)
Within the context of tectonic tsunamis generated in the near field we want to know the places with the maximum inundation, the extension of the inundation until it decreases to 0.5–1 m, and the average run-up
Summary
Countries exposed to coastal inundation have done a lot of work to develop their tsunami warning systems (Doi, 2003; Wächter et al, 2012). A regular 8.5 Mw earthquake can last for about 2 min, whereas we can consider tsunami generation nearly instantaneously after the source origin time. As a matter of fact, the regional W-phase method is running in real time in less than 5 min (Zhao et al, 2017) This method is based on waveform inversion theory; it is necessary to have an important number of broadband seismometers in the regional field. This paper tries to illustrate the possibility of replication of these examples in other countries with tsunami threat produced by earthquakes in the near field It is well-known, that tsunami heights are very sensitive to the spatial slip distribution of the seismic source (Geist, 2002; Ruiz et al, 2015).
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