Mechanism of the 2015 volcanic tsunami earthquake near Torishima, Japan

• Fukao, Yoshio

• Sandanbata, Osamu

• 杉岡, 裕子

• Ito, Aki

• Shiobara, Hajime

• Watada, Shingo

• Satake, Kenji

抄録

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 [M-w (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 M-zx, M-zy, 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.

収録刊行物

• Science Advances

  Science Advances 4 (4), eaao0219-eaao0219, 2018-04-04

  American Association for the Advancement of Science

キーワード

• Multidisciplinary

詳細情報

• CRID: 1050294045370414848
• NII論文ID: 120006466553
• DOI: 10.1126/sciadv.aao0219
• ISSN: 23752548
• HANDLE: 20.500.14094/90004864
• Web Site: https://www.science.org/doi/pdf/10.1126/sciadv.aao0219
• 本文言語コード: en
• 資料種別: journal article
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