日本地球惑星科学連合2018年大会

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[JJ] 口頭発表

セッション記号 S (固体地球科学) » S-TT 計測技術・研究手法

[S-TT50] 地震観測・処理システム

2018年5月23日(水) 15:30 〜 17:00 A10 (東京ベイ幕張ホール)

コンビーナ:吉見 雅行(産業技術総合研究所活断層・火山研究部門)、座長:木村 武志(防災科学技術研究所)

16:10 〜 16:25

[STT50-03] Regional evolution of network detection completeness in Japan

*Danijel Schorlemmer1Naoshi Hirata2Yuzo Ishigaki3Keiji Doi4Kazuyoshi Nanjo5Hiroshi Tsuruoka2Thomas Beutin1Fabian Euchner6 (1.GFZ German Research Centre for Geosciences、2.Earthquake Research Institute, University of Tokyo, Tokyo, Japan、3.Seismological and Volcanological Department, Japan Meteorological Agency, Tokyo, Japan、4.Osaka Regional Headquarters, Japan Meteorological Agency, Osaka, Japan、5.Global Center for Asian and Regional Research, University of Shizuoka, Shizuoka, Japan、6.ETH Zurich, Zurich, Switzerland)

キーワード:Seismic recording, Completeness, Statistical Seismology

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, e.g. the effects of the Tohoku-oki earthquake sequence. For practical purposes we deliver completeness estimates for catalog data of selected regions and document the conservative completeness estimates researchers can use when investigating the JMA catalog in different regions over different periods. 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.