1996年8月11日宮城県鬼首付近に発生した地震について

• 海野 徳仁

  東北大学大学院理学研究科地震・噴火予知研究観測センター

• 松澤 暢

  東北大学大学院理学研究科地震・噴火予知研究観測センター

• 堀 修一郎

  東北大学大学院理学研究科地震・噴火予知研究観測センター

• 中村 綾子

  東北大学大学院理学研究科地震・噴火予知研究観測センター

• 山本 明

  東北大学大学院理学研究科地震・噴火予知研究観測センター

• 長谷川 昭

  東北大学大学院理学研究科地震・噴火予知研究観測センター

• 吉田 武義

  東北大学大学院理学研究科地球物質科学

書誌事項

タイトル別名

• 1996 Onikobe Earthquakes and their Relation to Crustal Structure
• 1996ネン 8ガツ 11ニチ ミヤギケン オニコウベ フキン ニ ハッセイ シタ ジシン ニ ツイテ

抄録

Two earthquakes with magnitudes 5.9 and 5.7 occurred beneath the Onikobe geothermal area, northeastern Japan, on 11 August 1996. A detailed study of the earthquakes and their aftershocks revealed that the M5.9 earthquake occurred in the region between the Sanzugawa caldera and the Onikobe caldera perhaps along a geological fault. The bi-lateral fault slip motion was stopped at the caldera walls in both ends. The M5.7 earthquake with right-lateral strike slip type focal mechanism took place along the Onikobe caldera rim or a geological fault close to the caldera rim. On 13 August 1996, M4.9 earthquake occurred on the southwestern extension of the M5.7 fault and had a focal mechanism of strike slip type with some reverse fault components. The fault slip of the M4.9 earthquake did not extend into the Mukaimachi caldera. Recent earthquakes with magnitudes about 5 have occurred in this geothermal area almost every ten years. M4.9 earthquake occurred on the southwestern edge of the Onikobe caldera on 5 July 1976, having a focal mechanism of reverse fault-type. On 28 March 1985, a left-lateral strike slip earthquake with magnitude 5.3 took place also along the Onikobe caldera rim. The lengths of earthquake faults estimated from aftershock distributions are at most 10km and seem to be consistent with characteristic lengths of geological heterogeneity, i. e. lengths of geological faults and diameters of calderas in this area. Seismic tomography study shows that low S wave velocity areas are located inside the calderas. Relatively large earthquakes and their aftershocks occurred only within high S wave velocity areas. It seems reasonable to suppose that temperature inside the calderas is too high to generate earthquakes. Thermal structure is one of major factors that govern seismic activities in the crust.

収録刊行物

• 地震　第２輯

  地震　第２輯 51 (3), 253-264, 1998

  公益社団法人 日本地震学会

キーワード

• 1996 Onikobe earthquake
• Caldera
• Seismogenic zone
• Crustal structure
• Thermal structure

詳細情報

• CRID: 1390282679283638016
• NII論文ID: 10002502331
• NII論文ID: 10003848558
• NII書誌ID: AN00305741
• DOI: 10.4294/zisin1948.51.3_253
• ISSN: 18839029
• ISSN: 2186599X
• ISSN: 00371114
• NDL書誌ID: 4647672
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I4647672
• Web Site: https://www.jstage.jst.go.jp/article/zisin1948/51/3/51_3_253/_pdf
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