Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan
Fukao, Y.; Sandanbata, O.; Sugioka, H.; Ito, A.; Shiobara, H.; Watada, S.; Satake, K. (2018). Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan. Science Advances 4(4): eaao0219. https://dx.doi.org/10.1126/sciadv.aao0219
In: Science Advances. AAAS: New York. ISSN 2375-2548; e-ISSN 2375-2548, meer
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| Auteurs | | Top |
- Fukao, Y.
- Sandanbata, O.
- Sugioka, H.
- Ito, A.
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- Shiobara, H.
- Watada, S.
- Satake, K.
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| Abstract |
Tsunami earthquakes are a group of enigmatic earthquakes generating disproportionally large tsunamis relative to seismic magnitude. These events occur most typically near deep-sea trenches. Tsunami earthquakes occurring approximately every 10 years near Torishima on the Izu-Bonin arc are another example. Seismic and tsunami waves from the 2015 event [Mw (moment magnitude) = 5.7] were recorded by an offshore seafloor array of 10 pressure gauges, ~100 km away from the epicenter. We made an array analysis of dispersive tsunamis to locate the tsunami source within the submarine Smith Caldera. The tsunami simulation from a large caldera-floor uplift of ~1.5 m with a small peripheral depression yielded waveforms remarkably similar to the observations. The estimated central uplift, 1.5 m, is ~20 times larger than that inferred from the seismologically determined non–double-couple source. Thus, the tsunami observation is not compatible with the published seismic source model taken at face value. However, given the indeterminacy of Mzx, Mzy, and M{tensile} of a shallow moment tensor source, it may be possible to find a source mechanism with efficient tsunami but inefficient seismic radiation that can satisfactorily explain both the tsunami and seismic observations, but this question remains unresolved |
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