[S-SS13] Seismicity

[SSS13-P07] Continuous observation of ocean bottom earthquakes in Suruga Bay. - Hypocenter redetermination using velocity structure model obtained by Air-gun OBS refraction seismic survey.-

*Nakao Nagisa¹, Hisatoshi Baba¹, Takahito Nishimiya², Kayoko Tsuruga³ (1.Graduate School of Oceanography, Tokai University, 2.Meteorological Research Institute,Japan Meteorological Agency, 3.Tokyo University of Marine Science and Technology)

Keywords:Suruga Trough, Seismicity, Tokai Earthquake

Tokai Univ. and MRI are carrying out the ocean bottom earthquake observations in and around Senoumi Bank near Suruga Trough axial region, using 4 pop-up type Ocean Bottom Seismographs (OBSs) from October, 2011. The seismic activity obtained by these observations proved that most of them were aftershocks of the M 6.5 earthquake occurred in Suruga Bay in 2009.

In 2016, seismic reflection and refraction survey were carried out at Suruga Bay by the research vessel ‘Shinyomaru’ Tokyo University of Marine Science and Technology. 2-D seismic reflection system consists of three 10-ft containers for Air-gun sources, an air compressor, and streamer-cable systems (Tsuruga et al., 2017). We conducted seismic experiments along 4 survey lines located around Suruga Trough. One of the 4 lines, H28-L04 line was set in using OBSs stations, near Senoumi Bank.

Therefore, in order to investigate detailed seismic activity around Senoumi Bank in the central part of Suruga Bay, using velocity structure model obtained by Air-gun OBS refraction seismic survey.
In this presentation, we report characteristics of redetermination hypocenters obtained OBSs.