Publication Date:
2020-02-12
Description:
Modern near-field tsunami early warning systems must provide a tsunami alarm as early as 5 to 10 minutes after an earthquake. Working within this time limit, traditional seismic methods tend to underestimate the total moment magnitude in case of giant (Sumatra 2004, Tōhoku 2011) as well as slow, ‘tsunami’ (Java 2006, Mentawai 2010) earthquakes. Moreover, representation of a tsunami source as a point-source, i.e. location plus magnitude, is usually insufficient for a reliable near-field early warning. Using numerical simulation of earthquake rupture and associated crustal deformation and tsunami wave’s propagation, we demonstrate that recent high-precision real-time Global Navigation Satellite System (GNSS) arrays may serve as a key component of near-field tsunami early warning system. The main advantage of the GNSS-arrays, placed close to an epicenter, is that they directly measure surface displacements necessary for tsunami source inversion already during the earthquake. Taking the Great March 2011 Tōhoku-oki earthquake as an example, we demonstrate the ability of real-time GNSS to provide qualified tsunami early warning in only three minutes after beginning of the earthquake. To do so, we combine real-time Precise Point Positioning (PPP) processing with fast slip inversion and on-the-fly tsunami simulation. This allows the observation of the earthquake growth in almost real-time (plus about one minute processing overhead) by simultaneously computing tsunami warning levels. Already three minutes after the earthquake begins, GNSS-derived moment magnitude estimation reaches its final value of Mw = 9.0 and tsunami forecasting stabilizes as well.
Language:
German
Type:
info:eu-repo/semantics/article
Format:
application/pdf
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