Deep low-frequency earthquakes and the crust-mantle structure beneath the Seto Inland Sea

2017 Fiscal Year Final Research Report

• Project/Area Number: 26400452
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Kyoto University
• Principal Investigator: Kuge Keiko 京都大学, 理学研究科, 准教授 (50234414)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: 地震波速度 / トモグラフィー / 西日本

Outline of Final Research Achievements

This study suggests that the seismic wave speeds in the mantle wedge beneath the Seto Inland Sea, western Japan, where deep low-frequency earthquakes/tremor occur, can be lower than the values previously suggested. When the mantle wedge has low speeds of P and S waves, travel time tomography using first arrivals of P and S waves would estimate the values of the speeds to be higher than the true ones. The presence of velocity discontinuities around the mantle wedge (e.g., oceanic Moho) would affect the estimates. Using arrival times of later phases can help to correct the estimates, however, a problem about how to set velocity discontinuities arises.

Free Research Field

地震学