著者

熊谷 博之

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.108, no.4, pp.424-432, 1999-08-25 (Released:2009-11-12)

参考文献数

27

被引用文献数

9 12

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Possible tsunami deposits were found at two archeological sites along the Pacific coast near Hamana Lake in central Japan. This region has frequently suffered heavy damage from large earthquakes along the Nankai trough. Three sand deposits covering layers that include archeological remains were found at one of the sites. The ages of the sand deposits were constrained by remains just below the sand deposits, which showed good correspondence to the ages of three major historic earthquakes that seriously damaged this area, i.e., A.D. 1707, 1605, and 1498. These features strongly suggest that the sand deposits were caused by tsunami from the historic earthquakes. Core samples obtained near this site showed that a similar sequence continues into a deeper part, suggesting the existence of tsunami deposits of events older than A.D. 1498, before which few historical records are available in the Tokaido side. Further investigation of tsunami deposits in this area would yield useful information on the reconstruction of large earthquakes along the Nankai trough.

著者

熊谷 博之 中野 優

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.61, no.Supplement, pp.379-390, 2009-07-31 (Released:2013-11-21)

参考文献数

85

被引用文献数

1

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We review recent advances in quantification of the sources of volcano-seismic signals. Since the 1990s, there have been remarkable advances in quantitative understanding of the sources of volcano-seismic signals. These were made by integrated contributions from observation, analysis, and modeling studies in volcano seismology. We focus on the following topics in this review paper: Broadband seismic observations on active volcanoes, waveform inversions of volcano-seismic signals, and source models based on resonances of a fluid-filled crack, bubble dynamics, and repeated fracture and healing of magma. Broadband seismic observations revealed the general existence of very-long-period seismic signals with oscillation periods longer than a few seconds beneath active volcanoes. Development of waveform inversion methods enabled us to estimate source mechanisms of volcano-seismic signals, which indicate that crack geometry is the most common in volcano-seismic sources. Source models have been successfully used to interpret dynamic interactions between volcanic fluids and the surrounding solid rock. Quantitative studies of volcano seismology are now reaching a mature stage, and links with geological and geochemical studies will be important future directions to achieve a better understanding of magmatic and hydrothermal processes beneath active volcanoes.

著者

鍵山 恒臣 筒井 智樹 三ヶ田 均 森田 裕一 松島 健 井口 正人 及川 純 山岡 耕春 熊谷 博之 西村 裕一 宮町 宏樹 渡辺 了 西村 太志 高木 朗充 山本 圭吾 浜口 博之 岡田 弘 前川 徳光 大島 弘光 植木 貞人 橋本 恵一 仁田 交一 茂原 諭 中道 治久 汐見 勝彦 中原 恒 青木 重樹 青地 秀雄 井田 喜明

出版者

東京大学地震研究所

雑誌

東京大学地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.70, no.2/4, pp.33-60, 1996-03-15

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In recent years, investigations on the structures of volcanoes have been noteworthy for further understanding volcanic processes, including locations of magma reservoirs, magma rising process before eruptions and causes of related phenomena. In 1994, a joint experiment was conducted on Kirishima Volcanoes, Southern Kyushu, to reveal the structure and the magma supply system by a group of scientists from national universities under the National Research Project for the Prediction of Volcanic Eruptions. The experiment was carried out by seismological, electromagnetic and other geophysical methods. The following seven papers including this one present some results of the experiments. This paper outlines a seismic explosion experiment in Kirishima, and presents all data on the first motion. An extensive explosion seismic experiment was conducted on December 1, 1994. Observations were made along a 30-km major line lying in the NNW-SSE direction and other sub-lines which cross the major line in and around the Kirishima Volcanoes. Along these lines, 6 shots with a charge size of 200-250 kg, and 163 temporary observations were arranged by many universities and institutes. A newly developed data logger was used for these temporal observations, and the position of each site was determined by GPS. All 6 shots were successfully fired, and clear onset and significant phases were observed at most observation sites. A travel time diagram suggests that a high velocity layer crops out south of the Kirishima Volcanoes, while in the Kirishima Volcanoes, this layer is covered with a lower velocity layer, which is thick at the northern part. It is also suggested that a structural discontinuity exists between S3 and S4.

著者

堀 貞喜 石田 瑞穂 青井 真 井上 公 大久保 正 岡田 義光 小原 一成 笠原 敬司 木村 尚紀 熊谷 博之 汐見 勝彦 関口 渉次 根岸 弘明 野口 伸一 松本 拓己 山水 史生 藤原 広行 功刀 卓 浅野 陽一 関根 秀太郎 廣瀬 仁 松原 誠 安逹 繁樹 伊藤 喜宏 針生 義勝 松林 弘智 松村 稔 宮川 幸治 山品 匡史 坂無 雅子 雷 楓 伊東 明彦 岩田 知孝 ト部 卓 川勝 均 木下 繁夫 工藤 一嘉 纐纈 一起 佐藤 春夫 佐藤 比呂志 武井 恵雄 中尾 茂 平田 直 平原 和朗 堀家 正則 松澤 暢 山北 聡 綿田 辰吾 山野 誠

出版者

独立行政法人防災科学技術研究所

雑誌

防災科学技術研究所年報 (ISSN:09186441)

巻号頁・発行日

vol.15, pp."I-12"-"I-16", 2004-09-06

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地震調査研究推進本部の総合基本施策(「地震に関する観測、測量、調査及び研究の推進についての総合的かつ基本的な施策(平成11年4月23日)」)、及び調査観測計画(「地震に関する基盤的調査観測計画(平成9年8月29日)」、「地震に関する基盤的調査観測計画の見直しと重点的な調査観測体制の整備(平成13年8月28日)」、「地震に関する基盤的調査観測等の結果の流通・公開について(平成14年8月26日)」)等に基づき、高感度・広帯域地震観測施設と強震観測施設を整備し、観測網の維持・管理・運用を行う。これら基盤的観測網と防災科研の在来地震観測網から得られるデータの収集・処理を行い、気象庁、大学等のデータと合わせて蓄積・流通・公開を行う。また、防災科研が海外に整備した観測施設についても、円滑な維持・管理とともに、観測方式の高度化を行いつつ、データの収集・処理・蓄積・公開を行う。さらに、各観測網から得られるデータを用いて、高度な地殻活動のモニタリングを実施し、地震活動状況の推移を判断するための研究成果を創出する。