Restoration of interplate locking after the 2005 Off-Miyagi Prefecture earthquake, detected by GPS/acoustic seafloor geodetic observation

• Published in: Geophysical research letters Vol. 38; no. 1; pp. np - n/a
• Main Authors: Sato, Mariko, Saito, Hiroaki, Ishikawa, Tadashi, Matsumoto, Yoshihiro, Fujita, Masayuki, Mochizuki, Masashi, Asada, Akira
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 16.01.2011; American Geophysical Union
• Subjects: 2005 Off-Miyagi Prefecture earthquake; Acoustics; Boundaries; Earth sciences; Earth, ocean, space; Exact sciences and technology; GPS/acoustic; Horizontal; interplate coupling; Locking; Movements; Sea beds; seafloor geodetic observation; Seismic phenomena; Strain; Far East; Asia; Japan; strain; accumulation; Time series; coordinates; Eurasian Plate; velocity; epicenters; earthquakes; rupture; Global Positioning System; erratics; ocean floors; plate boundaries
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2010GL045689

A 7.2‐magnitude earthquake occurred on the plate boundary off Miyagi Prefecture, northeastern Japan, on 16 August 2005. From seafloor geodetic observations using the GPS/acoustic combination technique in this area, we have detected notable seafloor movements associated with, and subsequent to this event. The time series of horizontal coordinates obtained at the seafloor reference point MYGW, located about 10 km east of the epicenter, indicates that the strain accumulated for the interseismic period was partly released by the event and a constant strain accumulation restarted after 1–2 years of the post‐seismic period with an erratic movement. The horizontal velocity of MYGW after the restart above is estimated to be about 5.7 cm/year toward WNW relative to the Eurasian plate. Our result is consistent with those derived from terrestrial GPS measurements and implies that the interplate locking was restored in the rupture area of the 2005 event around 2007.