{"created":"2021-03-01T06:51:20.976018+00:00","id":32655,"links":{},"metadata":{"_buckets":{"deposit":"39edc609-0a3d-4286-8ccf-8d85034e0609"},"_deposit":{"id":"32655","owner":"1","owners":[],"pid":{"revision_id":0,"type":"depid","value":"32655"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00032655","sets":["80:4535:4649:4655","9:504:4538:4651:4656"]},"author_link":["126573","126572"],"item_4_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"1999年台湾集集地震の余震数予測の試み"}]},"item_4_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2000-09-22","bibliographicIssueDateType":"Issued"},"bibliographicIssueNumber":"1","bibliographicPageEnd":"91","bibliographicPageStart":"79","bibliographicVolumeNumber":"75","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":"In order to find a practical method to assess forthcoming activity of aftershocks, an attempt was made to predict a plausible range of the number of major aftershocks of the 1999 Chi-Chi, Taiwan earthquake of September 20 (UTC;Ms=7.7). Although a method of predicting the probability of aftershocks had been proposed, assuming that parameters in the modified Omori formula would not change during the period of prediction, such an assumption might sometimes be invalid at the time of the especially large aftershocks. For this reason, a range of the number of aftershocks was experimentally discussed between September 22 and November 21 based on the 5-95% or the 0-90% points of the Poisson distribution. As a result, 11 cases were successful among 13 trials, suggesting that a prediction of the range of the number of aftershocks will be available for practical use, at least to some extent.","subitem_description_type":"Abstract"},{"subitem_description":"1999年9月20日(世界時)に発生した台湾集集地震について,想定した期間にある大きさ以上の余震が何回起こるか,試験的な予測を試みた.予測が当たる確率を上げるためには適当な幅を考える必要があるが,ここでは90%くらいの確度を想定して,ポアソン分布の5%および95%点を予測数の上下限の幅として考えた.ただし,下限値が0に減少したときには,ポアソン分布の0～90%点をとれば十分かもしれない.また,期待値が5以下のときはその1/2～2倍くらい,期待値が20～30のときはその1/1.5～1.5倍くらいの範囲をとると,ある程度近似できる(その際,下限値を求めるときは小数点以下を切り捨てる).観測された余震のデータを改良大森公式にあてはめてその係数を定めれば,任意の期間に起こる余震数の期待値を求めることができる.これをもとに予測回数の幅を推測するが,期待値に誤差が見込まれるときは,それに応じて予測の幅を広げる必要が生じる.今回の台湾の余震活動では, 9月22日～11月21日までの2ヵ月間,初めは1日ごと,その後は1週間ごとにマグニチュード5.0以上の余震数を予測した.合計13回の予測の結果をみると, 11回が予測幅の範囲内に収まり, 2回が予測幅をそれぞれ一つ超過した.地震発生直後に入手できる地震データは不完全な場合が多く,具体的に予測の作業を行うときは,それによる不確かさも考慮しなければならない.このような難しさもあるが,今回の試行では, 85%程度の成功率を得た.どのくらい活発な余震活動がこれから先に見込まれるか,本稿のような方法によってある程度の目安が得られれば,それなりに役に立つのではないかと思われる.なお,期待値が与えられたときに,ポアソン分布の5～95%幅が具体的にどのような値をとるかを表の形で表し,また,参考までにその値を算出する近似式を示した.","subitem_description_type":"Abstract"}]},"item_4_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"126573","nameIdentifierScheme":"WEKO"}],"names":[{"name":"山科, 健一郎"}]}]},"item_4_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/0000032655","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_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Yamashina, Ken'ichiro"}],"nameIdentifiers":[{"nameIdentifier":"126572","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":"ji0751006.pdf","filesize":[{"value":"711.3 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"ji0751006.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/32655/files/ji0751006.pdf"},"version_id":"a0716bd5-6db8-4ab2-9738-c2ab93b697c1"}]},"item_keyword":{"attribute_name":"キーワード","attribute_value_mlt":[{"subitem_subject":"earthquake prediction","subitem_subject_scheme":"Other"},{"subitem_subject":"aftershock","subitem_subject_scheme":"Other"},{"subitem_subject":"modified Omori formula","subitem_subject_scheme":"Other"},{"subitem_subject":"Poisson distribution","subitem_subject_scheme":"Other"},{"subitem_subject":"the Chi-Chi earthquake","subitem_subject_scheme":"Other"}]},"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":"Experimental Prediction of the Number of Aftershocks of the 1999 Chi-Chi, Taiwan Earthquake","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Experimental Prediction of the Number of Aftershocks of the 1999 Chi-Chi, Taiwan Earthquake","subitem_title_language":"en"}]},"item_type_id":"4","owner":"1","path":["4655","4656"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2008-05-30"},"publish_date":"2008-05-30","publish_status":"0","recid":"32655","relation_version_is_last":true,"title":["Experimental Prediction of the Number of Aftershocks of the 1999 Chi-Chi, Taiwan Earthquake"],"weko_creator_id":"1","weko_shared_id":-1},"updated":"2022-12-19T04:08:41.125898+00:00"}