{"created":"2021-03-01T06:51:41.665104+00:00","id":32964,"links":{},"metadata":{"_buckets":{"deposit":"f9ce6a13-5c01-42bb-ad91-aa67a41e54dd"},"_deposit":{"id":"32964","owner":"1","owners":[],"pid":{"revision_id":0,"type":"depid","value":"32964"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00032964","sets":["80:4535:4797:4805","9:504:4538:4799:4806"]},"author_link":["128528","128527"],"item_4_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"3. 群発地震と前震の波形及びスペクトル特性 : 地震予知に関連して","subitem_alternative_title_language":"ja"}]},"item_4_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"1983-07-28","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"1","bibliographicPageEnd":"134","bibliographicPageStart":"65","bibliographicVolumeNumber":"58","bibliographic_titles":[{"bibliographic_title":"東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo"}]}]},"item_4_description_13":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_4_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Through the analyses of waveforms and spectra for the earthquake swarm, foreshock and ordinary seismic activities, some differences in the activity mode are found among those activities. The most striking difference is the \"\"similarity of waveform\"\". The earthquake swarm activity which occurred in a certain short time interval mainly consists of events with similar waveforms, belonging to the event group called \"\"similar earthquakes\"\" or an \"\"earthquake family\"\". On the other hand, the foreshock activity consists of events with an individual waveform character. Similarly, the rate of the occurrence of earthquake families is very low in ordinary seismic activity. The epicenters of earthquakes in a family are distributed within a small area, about 400meters for a family with Mmax≅3.0, in contrast with a wide area for foreshocks. The source spectra of earthquake swarms also show some features differing from those of other activities. The corner frequencies of events in the same family are almost constant, and their values depend on the size of the largest earthquake within the family. On the other hand, the corner frequencies of foreshocks differ from event to event, and there is no simple linear relation between the corner frequency and the earthquake size. Such behavior suggests that the earthquakes in a family occur on the same fault plane as a repeated slipping or a repeated incomplete rupture, and foreshocks occur independently in a heterogeneous zone near the main shock. If such differences are applicable for the other sequences, continuous monitoring of waveforms and spectra gives us some useful information for distinguishing a foreshock sequence from an earthquake swarm.","subitem_description_type":"Abstract"},{"subitem_description":"ある地域における地震活動が活発化した場合,それが群発地震であるか,前震であるかを識別することは地震学的にも,又地震予知の見地からも極めて重要な問題である.ここでは,群発地震についての波形,並びにスペクトル解析から,群発地震のもつ特徴を明らかにすると共に,同様な解析を前震活動にも適用し,両者の性質の違いを見出そうとするものである.対象とした地域は関東地方である.堂平観測所並びにその衛星観測所の資料から,過去14年間で15個の群発地震,及び3個の前震活動を選び,それぞれの波形解析及びスペクトル解析を行なった. I.群発地震の波形解析 早送り記録の重ね合わせにより波形について調べた結果:1.ある時間帯(活動度により異なる)に発生する地震は非常に似かよった波形を示し,所謂\"\"相似地震\"\"によって構成される. 2.一連の相似地震の活動が終ると,別の相似地震群が隣接地域において発生する(活動が高い場合).3.相似地震の震源域は数百米である(Mmax≈3). 4.相似地震に含まれる最大地震は,その系列の後半に発生する. II.群発地震のスペクトル解析 アナログ型バソドパスフイルターの記録を用い,それぞれの相似地震群の震源スペクトルを求めた.主な結果は: 1.相似地震のコーナー周波数は,ある範囲の地震(ΔM≈2)に対し略一定である. 2.ある相似地震のコーナー周波数は,その地震群に含まれる最大地震の大きさに依存する. 3.従って,相似地震に含まれる最大地震の大きさはストレスドロップ量(スベリ量)によって制限される.III.前震の波形及びスペクトル解析 群発地震で用いた同じ方法により,前震活動及び一部定常活動の地震についても解析を行なった.主な結果は: 1.前震はそれぞれ独立した波形を持ち,群発地震で見られたような相似地震は現われない. 2.前震活動におけるそれぞれの地震のコーナー周波数は複雑に分布し,群発地震でみられたような地震の大きさ(モーメント)と震源の大きさとの間で単純な直線関係は見られない. 3.定常活動における相似地震の発生率は極めて低い. 以上,群発地震,前震及び定常活動における地震について,それぞれの活動様式の特徴を明らかにした.この様な特徴はそれぞれの地震群の発生様式の違いに起因するものであろうと推定される.すなわち,群発地震は局所的な応力集中の場で発生し,そのため極めてせまい範囲おそらく同じ断層面上で,繰り返し発生するのに対し,前震は,広域応力場での発生のため,広範囲の領域で発生したことを反映したものであろう.従って,若しこの楼な違いが,他の前震及び群発地震についても適用されるならば,地震波形並びにスペクトルの継続的な監視が地震予知のための1資料として役立つことが期待される.","subitem_description_type":"Abstract"}]},"item_4_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"128528","nameIdentifierScheme":"WEKO"}],"names":[{"name":"辻浦, 賢"}]}]},"item_4_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/0000032964","subitem_identifier_reg_type":"JaLC"}]},"item_4_publisher_20":{"attribute_name":"出版者","attribute_value_mlt":[{"subitem_publisher":"東京大学地震研究所"}]},"item_4_source_id_10":{"attribute_name":"書誌レコードID","attribute_value_mlt":[{"subitem_source_identifier":"AN00162258","subitem_source_identifier_type":"NCID"}]},"item_4_source_id_8":{"attribute_name":"ISSN","attribute_value_mlt":[{"subitem_source_identifier":"00408972","subitem_source_identifier_type":"ISSN"}]},"item_4_subject_15":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"453","subitem_subject_scheme":"NDC"}]},"item_4_text_21":{"attribute_name":"出版者別名","attribute_value_mlt":[{"subitem_text_value":"Earthquake Research Institute, University of Tokyo"}]},"item_4_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"Earthquake Research Institute"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Tsujiura, Masaru"}],"nameIdentifiers":[{"nameIdentifier":"128527","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2017-06-26"}],"displaytype":"detail","filename":"ji0581003.pdf","filesize":[{"value":"4.2 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"ji0581003.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/32964/files/ji0581003.pdf"},"version_id":"9b8fa714-ba41-4696-b6cb-f8674b9d8961"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"departmental bulletin paper","resourceuri":"http://purl.org/coar/resource_type/c_6501"}]},"item_title":"3. Waveform and Spectral Features of Earthquake Swarms and Foreshocks : in Special Reference to Earthquake Prediction","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"3. Waveform and Spectral Features of Earthquake Swarms and Foreshocks : in Special Reference to Earthquake Prediction","subitem_title_language":"en"}]},"item_type_id":"4","owner":"1","path":["4805","4806"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-05-30"},"publish_date":"2008-05-30","publish_status":"0","recid":"32964","relation_version_is_last":true,"title":["3. Waveform and Spectral Features of Earthquake Swarms and Foreshocks : in Special Reference to Earthquake Prediction"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-19T04:08:52.303753+00:00"}