著者
高橋 浩晃 宮村 淳一
出版者
北海道大学大学院理学研究院自然史科学部門(地球物理学) = Department of Natural History Sciences (Geophysics), Graduate School of Science, Hokkaido University
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.72, pp.177-190, 2009-03-15

We investigate the activity of deep low-frequency earthquakes (DLE) in Japanese Islands by JMA hypocenter catalogue during 1997 to 2008. It is confirmed that DLE cluster is distributed in every region. This implies that DLE phenomenon is common in Japanese subduction zone. Many active DLE clusters are identified in and around the quaternary volcanoes in whole area. There are also many non-volcanic clusters in Hokkaido and Tohoku regions, but very few in Kanto, Koushinetsu, Chubu, Hokuriku and Kyushu regions. High activity of non-volcanic clusters is observed in Kinki region. No clear correlation between DLE number and volcano activity index during 100 and 10,000 years is recognized. This fact implies the possibility that DLE activity is not precursor signal of shallow volcanic activities such as eruption at any time. Lower limit of DLE hypocenter depth generally coincides with depth of Moho discontinuity of each region. This may indicates that structure of upper mantle and lower crust and its boundary strongly control the occurrence of DLE's.
著者
一柳 昌義 笠原 稔 高橋 浩晃 岡崎 紀俊 高橋 良 大園 真子
出版者
北海道大学大学院理学研究院
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.77, pp.5-13, 2014-03-19

An earthquake swarm begun at the end of January, 2012 and the activity reached a peak in middle February, then gradually decreased by the end of April, in the Nigorikawa caldera, Hokkaido. The largest earthquake was the MJMA3.6 event which occurred on 15 February 2012 with maximum intensity 3.Temporal seismic observation with two stations carried out from 20 February to 9 April in the caldera. Detailed hypocenter distribution estimated by using both data temporal and secular observations shows two clusters, one of them is aligned along the northern caldera wall and another is located at eastern outside of caldera. Strike of alignment epicenter of the north cluster shows NE-SW direction, which is in good agreement with one of the nodal plane of focal mechanism of the largest event.
著者
一柳 昌義 高橋 浩晃 山口 照寛 東 龍介 山田 卓司 大園 真子 眞城 亮成 笠原 稔 谷岡 勇市郎
出版者
北海道大学大学院理学研究院
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.78, pp.37-51, 2015-03-19

An earthquake swarm begun at 15 July 2012 in Nakagawa town of northern Hokkaido. The largest earthquake with MJMA4.3 occurred on 16 July 2012. We carried out temporal seismic observation with seven stations from 18 July 2012 to the last October 2012. Hypocenters were calculated using the Double-Difference hypocenter determination procedure with a local one dimensional P-wave velocity structure. Precise hypocenter data indicated that epicenters were distributed in very narrow area of 2 km×2 km with shallow depth from 4 km to 7 km. Earthquakes after middle of August occurred only in southern part of the region and depth had got shallower with time. Hypocenters indicated no clear alignment in consistent with any nodal planes of major earthquakes. An independent hypocenter cluster with shallower than 2 km was observed above the main activity area. A slow slip event (SSE) with Mw 5.4 coincidentally detected by GNSS crustal deformation data during the swarm. This swarm was situated at the southeastern end of the fault of SSE. This fact suggested that seismic swarm might triggered SSE or was induced by SSE.
著者
高橋 浩晃 前田 宜浩 笠原 稔
出版者
北海道大学大学院理学研究院自然史科学部門(地球物理学)
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.72, pp.399-410, 2009-03-15

We investigate the characteristics of great earthquakes occurring in the central Kuril Islands on 1915, 1918, 2006 and 2007. Comparisons of seismic intensity distributions, tsunami data and waveforms of above four events were made. Though magnitudes of these earthquakes were almost the same, only the 1915 event did not generate observable tsunami. This fact may be due to deep focal depth of this earthquake. Similarities of seismic intensity distributions between the 1915, 1971 and 2008 deep-focus earthquakes also imply that the 1915 event was the deep-focus event in the northeastern Okhotsk Sea. Waveform properties of the 1915 and 2008 events supports above hypothesis. We conclude, therefore, that the 1915 earthquake was not the event in the central Kuril Island but in the Okhotsk Sea with deep depth. Large tsunami and widespread felt area of the 1918 earthquake show that this event was a typical shallow-dipping thrust event on plate boundary as indicated by previous studies.
著者
一柳 昌義 山口 照寛 高田 真秀 東 龍介 黒井 和典 山田 卓司 高橋 浩晃 前田 宜浩
出版者
北海道大学大学院理学研究院
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.76, pp.1-13, 2013-03-19

On December 2, 2010, MJMA4.6 shallow felt earthquake occurred beneath southeastern part of Sapporo city. Three temporal seismic stations were installed near epicentral area. Reliable hypocenter data estimated by double difference procedure with local seismic velocity structure indicated clear southeastern-dipping distribution. Fault plane from focal mechanism estimated from P-wave polarization well agreed with this hypocenter distribution. Geometry of hypocenter distribution was also well consistent with an anticline structure and possible buried active fault estimated for earthquake disaster damage assumption by local government. Recalculation of hypocenters of the 1985, 1990, and 2010 felt earthquakes under equal condition implied that epicentral locations of these three events were approximately same. These facts implied possible stress concentration in epicentral region.
著者
高橋 浩晃 笠原 稔
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.57, no.2, pp.115-130, 2004-12-27 (Released:2010-03-11)
参考文献数
62
被引用文献数
2

The Tokachi-oki earthquake (MJMA8.0) occurred on September 26, 2003 (JST) off southeastern Hokkaido, Japan. We investigate the seismic activity before and after the mainshock using hypocenter catalogues produced by Japan Meteorological Agency and Hokkaido University. A decline of seismic activity and a seismic gap in the asperity of the 2003 earthquake had been clearly recognized from the early 1990's to just the mainshock faulting. Similar low seismicity had been observed before the former 1952 Tokachi-oki earthquake (MJMA 8.2). These facts may reflect that the plate boundary fixed loosely has become tight coupling during one seismic cycle. A relatively low seismicity patch during the interseismic phase corresponds to the asperity. This suggests that interseismic seismic activity is strongly controlled by existence of the asperity. The aftershock region of the 2003 earthquake is approximately 160km by 160km, which is slightly smaller than that of the 1952 earthquake. This feature is in good agreement with the slip distributions of the 1952 and 2003 earthquakes estimated from tsumani waveform inversions. Large aftershocks are located out of the asperity, which may reflect the stress status in and around the asperity. Remarkable triggered seismic activity has begun just after the mainshock along the volcanic front in the eastern Hokkaido.
著者
清水 洋 松本 聡 酒井 慎一 岡田 知己 渡辺 俊樹 飯尾 能久 相澤 広記 松島 健 高橋 浩晃 中尾 茂 鈴木 康弘 後藤 秀昭 大倉 敬宏 山本 希 中道 治久 山中 浩明 神野 達夫 三宅 弘恵 纐纈 一起 浅野 公之 松島 信一 福岡 浩 若井 明彦 大井 昌弘 田村 圭子 木村 玲欧 井ノ口 宗成 前原 喜彦 赤星 朋比古 宇津木 充 上嶋 誠 王 功輝 ハザリカ ヘマンタ 矢田 俊文 高橋 和雄
出版者
九州大学
雑誌
特別研究促進費
巻号頁・発行日
2016-04-22

2016年熊本地震について、地震活動や地殻変動、活断層、火山活動への影響、地震災害の特徴などを調査した。その結果、熊本地震は布田川・日奈久断層帯の右横ずれ運動によって発生したが、複数の断層面と複雑な断層形状を持つことを明らかにした。また、建物被害や土砂災害の地盤との関係、特に、地盤の過剰間隙水圧が地すべりの発生要因であることを明らかにした。さらに、災害情報や災害過程、被災救援、エコノミークラス症候群などについての調査から、広域複合災害の問題点と対応策を提示した。
著者
高橋 浩晃 大園 真子 宮町 宏樹 谷岡 勇市郎 蓬田 清 吉澤 和範 中尾 茂 一柳 昌義 山口 照寛 ゴルディエフ エフゲニー ブイコフ ビクター ゲラシメンコ ミハイル シェスタコフ ニコライ ワシレンコ ニコライ プリトコフ アレキサンダ レビン ユーリ ワレンチン ミハイロフ コスティレフ ドミトリ チェブロフ ダニラ セロベトニコフ セルゲイ
出版者
北海道大学
雑誌
基盤研究(A)
巻号頁・発行日
2013-04-01

ロシア極東地域から中国東北部を含むアジア北東地域のテクトニクスの解明を目指し,地震とGNSS観測を実施した.2011年東北地方太平洋沖地震による広域的な余効地殻変動が観測され,ロシア沿海州地方は地震時変動を上回る変位が得られた.ロシア極東地域に展開した広帯域地震観測網のデータから,当該地域の上部マントル地震波速度構造を明らかにし日本海下に低速度異常を確認した.上部マントルの粘弾性構造の推定から,日本列島周辺で繰り返し発生する巨大地震がアジア北東地域に長期的な余効変動を引き起こしてきた事実を明らかにした.また当該地域の特徴的な地震活動を明らかにした.
著者
一柳 昌義 高橋 浩晃 山口 照寛 岡田 和見 大園 真子 岡崎 紀俊
出版者
北海道大学大学院理学研究院
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.79, pp.1-8, 2016-03-19

An M5.0 shallow earthquake occurred on 4 June 2015 in the eastern Hokkaido. In order to evaluate aftershock activity, three temporal seismic stations had been operated in the focal region from 4 June 2015 to 22 August 2015. Hypocenters calculated with a local seismic velocity structure indicated clear southwestern-dipping distribution. This alignment on a plane was consistent with one of nodal plane of mainshock focal mechanism. This earthquake and historical records suggested higher seismic activity in this region.
著者
一柳 昌義 シェスタコフ ニコライ 奥山 哲 大園 真子 笠原 稔 高橋 浩晃
出版者
北海道大学大学院理学研究院
雑誌
北海道大学地球物理学研究報告 (ISSN:04393503)
巻号頁・発行日
vol.81, pp.17-26, 2018-03-19

A M5.6 shallow earthquake occurred on 8 July 2014 in middle east Iburi region, southwestern Hokkaido. Maximum seismic intensity of 5- was observed at Shiraoi town. Three temporal seismic stations had been installed in the focal region from 9 July 2014 to 30 April 2015. We determined 384 aftershock hypocenters by the double-difference tomographic hypocenter determination with proper seismic velocity structure. Relocated aftershocks were clearly distributed on a southeastern ward dipping plane with 5~10 km depth. This configuration agreed with a nodal plane of mainshock focal mechanism. Aftershocks occurred in surrounding part of a low seismicity patch. Mainshock was located deepest part of aftershock zone. These facts suggested that mainshock rupture propagated from deep to shallow, and a low seismicity patch was mainshock slip area. No clear correlation between this earthquake sequence and nearest active Tarumae volcano activity were identified.