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Assessment of nonlinear site response at ocean bottom seismograph sites based on S-wave horizontal-to-vertical spectral ratios: a study at the Sagami Bay area K-NET sites in Japan
https://nied-repo.bosai.go.jp/records/5061
https://nied-repo.bosai.go.jp/records/5061aef00a8c-b9c1-4a98-b15b-2a03f8a5f0bf
| Item type | researchmap(1) | |||||||||||||||
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| 公開日 | 2023-03-30 | |||||||||||||||
| タイトル | ||||||||||||||||
| 言語 | en | |||||||||||||||
| タイトル | Assessment of nonlinear site response at ocean bottom seismograph sites based on S-wave horizontal-to-vertical spectral ratios: a study at the Sagami Bay area K-NET sites in Japan | |||||||||||||||
| 言語 | ||||||||||||||||
| 言語 | eng | |||||||||||||||
| 著者 |
Yadab P. Dhakal
× Yadab P. Dhakal
× Shin Aoi
× Takashi Kunugi
× Wataru Suzuki
× Takeshi Kimura
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| 抄録 | ||||||||||||||||
| 内容記述タイプ | Other | |||||||||||||||
| 内容記述 | We analyzed S-wave horizontal-to-vertical (S-H/V) spectral ratios at six ocean bottom seismograph (OBS) sites of K-NET located in the Sagami Bay area of Japan for nonlinear site responses. The degree of nonlinearity was computed by comparing the S-H/V spectral ratios for strong motions (PGA = 20 cm/s(2)) with those for weak motions (PGA < 20 cm/s(2)). Our analyses, which showed that the weak-motion S-H/V spectral ratios differ from site to site, indicate that the underlying site geology is not uniform at the OBS sites. It was found that the threshold PGA causing a nonlinear site response is generally different from site to site. Recordings having horizontal PGAs greater than about 50-150 cm/s(2) display clear signatures of nonlinear site effects, i. e., the shift of predominant frequencies to lower ones and/or the decrease in high-frequency spectral ratios. We also found that the degree of nonlinearity is generally larger at the OBS sites due to the smaller threshold motions that cause a nonlinear site response compared with the available data at land sites. The above findings suggest the possibility of a widespread nonlinear site response at the OBS sites for offshore earthquakes with a large magnitude. However, frequencies lower than about 2 Hz are not affected by the nonlinear site response in the analyzed data ranges (PGA < 467 cm/s(2)). These results indicate the need for careful utilization of recorded strong motions at OBS sites for applications such as real-time ground motion predictions as front detections. | |||||||||||||||
| 言語 | en | |||||||||||||||
| 書誌情報 |
en : EARTH PLANETS AND SPACE 巻 69, 号 29 |
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| 言語 | en | |||||||||||||||
| 出版者 | SPRINGEROPEN | |||||||||||||||
| ISSN | ||||||||||||||||
| 収録物識別子タイプ | ISSN | |||||||||||||||
| 収録物識別子 | 1880-5981 | |||||||||||||||
| DOI | ||||||||||||||||
| 関連識別子 | 10.1186/s40623-017-0615-5 | |||||||||||||||
