日本地球惑星科学連合2015年大会

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インターナショナルセッション(口頭発表)

セッション記号 S (固体地球科学) » S-SS 地震学

[S-SS01] Exploring our limits in understanding earthquakes and improving our knowledge -CSEP Experiment in Japan-

2015年5月24日(日) 16:15 〜 18:00 102B (1F)

コンビーナ:*鶴岡 弘(東京大学地震研究所)、Danijel Schorlemmer(GFZ German Research Centre for Geosciences)、平田 直(東京大学地震研究所)、座長:庄 建倉(統計数理研究所)、石辺 岳男(東京大学地震研究所)

16:45 〜 17:00

[SSS01-10] History of network detection completeness in Japan

*Danijel SCHORLEMMER1Naoshi HIRATA2Yuzo ISHIGAKI3Kazuyoshi NANJO4Hiroshi TSURUOKA2Thomas BEUTIN1Fabian EUCHNER5 (1.GFZ German Research Centre for Geosciences, 14473 Potsdam, Germany、2.Earthquake Research Institute, University of Tokyo, Tokyo 113-0032, Japan、3.Seismological and Volcanological Department, Japan Meteorological Agency, Tokyo 100-8122, Japan、4.Institute of Advanced Science, Yokohama National University, Yokohama 240-8501, Japan、5.Institute of Geophysics, ETH Zurich, Switzerland)

キーワード:catalog completeness, earthquake recording, statistical seismology, earthquake statistics, earthquake forecasting, seismic hazard

An important characteristic of any seismic network is its detection completeness, which should be considered a function of space and time. Many researchers rely on robust estimates of detection completeness, especially when investigating statistical parameters of earthquake occurrence like earthquake rates. Contrary to traditional approaches, we do not estimate completeness using methods in which the completeness magnitude is defined as the deviation of the frequency-magnitude distribution from the linear Gutenberg-Richter relation. Here, we present a method based on empirical data only: phase data, station information, and the network-specific attenuation relation. For each station of the network we estimate a time-dependent distribution function describing the detection capability depending on magnitude and distance to the earthquake. For each point in time, maps of detection probabilities for certain magnitudes or overall completeness levels are compiled based on these distributions. Therefore, this method allows for inspection of station performances and their evolution as well as investigations on local detection probabilities even in regions without seismic activity.

We present a full history of network detection completeness for Japan and discuss details of this evolution. These results are compared with estimated completeness levels of other methods and with completeness levels in other regions of the World. We present scenario computations showing the impact of different possible network failures. All presented results are published on the CompletenessWeb (www.completenessweb.org) from which the user can download completeness data from all investigated regions, software codes for reproducing the results, and publication-ready and customizable figures.