著者

㓛刀 卓 青井 真 中村 洋光 鈴木 亘 森川 信之 藤原 広行

出版者

公益社団法人 日本地震学会

雑誌

地震 第2輯 (ISSN:00371114)

巻号頁・発行日

vol.65, no.3, pp.223-230, 2013-01-31 (Released:2013-07-19)

参考文献数

7

被引用文献数

14 15

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We present an improved implementation of the approximating filter for real-time seismic intensity calculations proposed in previous work. As earthquake early warning (EEW) systems become ever more widely used, the current method of computing a JMA (Japan Meteorological Agency) seismic intensity shows a serious problem since it introduces a time delay resulting from frequency domain filtering. In order to improve this method to permit real-time calculations suitable for EEW systems, we have proposed a real-time seismic intensity computed using an approximating filter in the time domain. For a simple computing system such as a strong-motion seismograph, it is straightforward to calculate the real-time seismic intensity because the approximating filter consists of only four first-order filters and one second-order filter. Based on testing using K-NET and KiK-net strong-motion seismographs, we have found that a strong-motion seismograph has enough computational capacity to undertake more sophisticated filtering. Here, we develop an approximating filter consisting of six second-order filters applied in the time domain for accurate real-time seismic intensity calculation. The relationship between the JMA seismic intensity and the real-time seismic intensity calculated using the improved approximating filter is examined using a large number of strong motion records. The results show that the differences between the JMA seismic intensities and the real-time seismic intensities are less than 0.1 for 99% of all records. Although the improved filter requires twice as much computation power as the previous approximating filter, it is suitable for EEW systems that require more accurate real-time calculations of seismic intensity.

著者

久保 久彦 鈴木 亘 㓛刀 卓 青井 真

出版者

公益社団法人 日本地震工学会

雑誌

日本地震工学会論文集 (ISSN:18846246)

巻号頁・発行日

vol.17, no.4, pp.4_13-4_29, 2017 (Released:2017-08-31)

参考文献数

20

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2015年小笠原諸島西方沖の地震をはじめとする小笠原諸島周辺の深発地震による地震動の特性把握および予測を目的として,本研究では強震動指標の空間的な分布やその距離減衰の様相を調べた上で,深発地震による地震動の距離減衰式を構築した.深発地震による地震動の距離減衰は地域毎に様相が異なっており,東日本前弧,東日本背弧,西日本および伊豆半島から伊豆・小笠原諸島にかけた地域の順で各地域への波線経路上での内部減衰と散乱減衰の双方またはいずれかが弱いと考えられる.これを踏まえて本研究では各地域で異なる非幾何減衰係数を持つ距離減衰式を提案している.また深発地震時の地盤増幅を評価した上で,過去の地震を対象とした地震動予測を試みた.