An observational investigation of plate coupling in the 1771 Yaeyama earthquake source area

2016 Fiscal Year Final Research Report

• Project/Area Number: 26287104
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Partial Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Shizuoka University
• Principal Investigator: Ando Masataka 静岡大学, 防災総合センター, 客員教授 (80027292)
• Co-Investigator(Kenkyū-buntansha): 生田 領野 静岡大学, 理学(系)研究科(研究院), 講師 (60377984) ; 宗林 留美 (福田留美) 静岡大学, 理学(系)研究科(研究院), 准教授 (00343195) ; 中村 衛 琉球大学, 理学部, 准教授 (60295293)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 琉球海溝 / 海底地殻変動 / プレートカップリング / キネマティックGPS / 音響測距 / XCTD / 1771年八重山地震 / 先島諸島

Outline of Final Research Achievements

This research purposes to clarify the plate coupling of the two plates along the western Ryukyu Trench to consider the possibility of large subduction earthquakes. In 2014, three seafloor-crustal-deformation transponders were installed off Hateruma Island, Okinawa Prefecture, and the position of these seafloor units was monitored every year. The analysis of the data obtained from 2014 to 2016, the seafloor position was found to change with a velocity -5.7 ± 9.8 cm/y northing and 2.1 ± 5.5 cm/y easting. This implies that the seafloor site moved southward relative to Hateruma Island, north of the seafloor site, indicating that the area extensional. However, it is difficult to conclude the area is extensional or compressional because of the large errors. Further observation is necessary to obtain reliable results of crustal deformation in the tectonic area.

Free Research Field

地震学