S24B-07
Present and Future of Metropolitan Seismic Observation network (MeSO-net) in Japan

Tuesday, 15 December 2015: 17:30
307 (Moscone South)
Naoshi Hirata1, Shigeki Nakagawa2, Shin'ichi Sakai2, Ryo Honda3, Hisanori Kimura4, Yannis Panayotopoulos1 and Masayuki Kano1, (1)Earthquake Research Institute, University of Tokyo, Tokyo, Japan, (2)University of Tokyo, Bunkyo-ku, Japan, (3)Hot Springs Research Institute of Kanagawa Prefecture, Shizuoka, Japan, (4)NIED National Research Institute for Earth Science and Disaster Prevention, Tsukuba, Japan
Abstract:
Tokyo and its vicinity are most seismically risky areas in the world. To prepare for the seismic disaster we have started a series of integrated Tokyo Metropolitan projects for disaster mitigation since 2002.The current Tokyo Metropolitan Project (Phase III) has started in 2012 with a new project name as “Special Project for Reducing Vulnerability for Urban Mega-earthquake Disasters” to use MeSO-net data for constructing 3-D velocity and Q structure beneath the greater Tokyo. We aim to collect data for regional characterization to access seismic hazard produced by subduction of Philippine Sea and Pacific plates.

The data from MeSO-net are continuously collected at the data management center in the Earthquake Research Institute (ERI), the University of Tokyo, with a sampling rate of 200 Hz. The data are 3-componnent accelerogram with a full scale of +/- 1,500 gal for horizontal and +/-500 gal for vertical component and the effective dynamic range is 135dB at 40Hz. Available frequency range is from 0.05 to 85 Hz, which is good for travel time analysis of body waves to ambient noise analysis for surface waves.

We have successfully operated MeSO-net for about 7 years without serious malfunction. We collect more than 150 TB continuous ground motion data with more than 100K earthquakes including the 2011 Tohoku-oki earthquake and all its aftershocks. The data are used many studies (e.g., Nakagawa et al., 2010,2015; Ishibe et al., 2015; Denolle et al., 2014) and currently prepared for disclosing both in continues and event-by-event format.

We are developing a fully automatic earthquake detection/location system for local earthquakes beneath MeSO-net. A numerical system to estimate ground motions at an arbitrary location without MeSO-net station is under developing (Kano et al., 2015).We also install a sensor system in a building for monitoring motion and damages by a large earthquake (Nakashima et al., 2015). Those studies are eventually integrated to develop an advanced earthquake early warning system, which enables us to predict strong motions in an upper floor of a high-rise building.

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