|Title||Local tsunami warnings: Perspectives from recent large events|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Melgar D, Allen R.M, Riquelme S., Geng JH, Bravo F., Baez J.C, Parra H., Barrientos S., Fang P., Bock Y, Bevis M., Caccamise D.J, Vigny C., Moreno M., Smalley R.|
|Journal||Geophysical Research Letters|
|Type of Article||Article|
|Keywords||GPS; inversion; models; near-field; runup; tohoku-oki earthquake; tsunami warning|
We demonstrate a flexible strategy for local tsunami warning that relies on regional geodetic and seismic stations. Through retrospective analysis of four recent tsunamigenic events in Japan and Chile, we show that rapid earthquake source information, provided by methodologies developed for earthquake early warning, can be used to generate timely estimates of maximum expected tsunami amplitude with enough accuracy for tsunami warning. We validate the technique by comparing to detailed models of earthquake source and tsunami propagation as well as field surveys of tsunami inundation. Our approach does not require deployment of new geodetic and seismic instrumentation in many subduction zones and could be implemented rapidly by national monitoring and warning agencies. We illustrate the potential impact of our method with a detailed comparison to the actual timeline of events during the recent 2015 M(w)8.3 Illapel, Chile, earthquake and tsunami that prompted the evacuation of 1 million people.
By leveraging source information from regional GPS and seismic networks, we have demonstrated the potential speedup in tsunami intensity estimation at the local coastlines adjacent to large events. Rapid magnitude estimates and more elaborate source products such as moment tensors and finite fault models can be used as the initial condition for fully nonlinear rapid tsunami models that can be computed within 2 min. A detailed analysis of the recent Mw8.3 Illapel, Chile, earthquake demonstrated that in the first 5 min substantially improved information on the expected intensity of the tsunami could have been available, potentially providing improved situational awareness for government agencies and likely a reduction in casualties.