報告書番号

U99023

タイトル（和文）

1999年台湾集集地震調査速報

タイトル（英文）

Quick Investigation Report on the 1999 Taiwan Jiji Earthquake

概要 （図表や脚注は「報告書全文」に掲載しております）

台湾集集地震は1999年9月21日1時47分（現地時刻）に発生した。震源は南投県集集鎮付近でUSGSによるマグニチュードは7.6である。南投県と台中県の一部では台湾震度階級で震度6を記録した。当所では10月6-12日の間にて電力設備の現地被害調査、地震断層調査を行った。地震断層は台中盆地西縁の車籠埔断層にほぼ沿って約70kmにわたり出現した。基本的に南北走向で東上りの逆断層であるが、北端部で屈曲し走向を北西－南東～東-西にかえ、屈曲部付近で最大の変位量（約10ｍ）を有するという特徴がある。送電鉄塔での主な被害は、地盤の変位による鉄塔基礎の損傷と鉄塔の倒壊・傾斜および碍子損傷や電線の切断・短絡で、幹線345kVを含む鉄塔約500基が被災した。また南部から北部への送電系統の要に位置する中寮開閉所にて多数の支持碍子、避雷器の破損やガス遮断器全体の傾斜等の被災があった。水力発電施設等の被害は軽微だったが、石岡ダム（取水堰）が地震断層の直撃を受けて崩壊した。

概要 （英文）

The Taiwan Jiji Earthquake occurred at 1:47 of September 21st, 1999, which caused unprecedented damages around mid-Taiwan area. The epicenter is located at Jiji in mid-Taiwan, and the moment magnitude announced by USGS, USA is 7.6. The Taiwan seismic intensities in a part of Nantou Prefecture and a part of Taichung Prefecture were recorded 6. CRIEPI carried out in-situ damage investigation during October 6th to 12th, paying main attention to earthquake surface fault and electric facilities. The earthquake surface fault emerged on the ground surface ranging about 70km almost along the Chelungpu active Fault which is located at the west end of Taichung Basin. It is a reverse fault with the eastward slope and with the strike of basically north-south direction, but it winds at the north end and changes its strike toward northwest-southeast to east-west. Its special feature is that it has the maximum net-slip of about 10m near the bend. About 500 transmission towers were damaged including 345kV arterial lines. The forms of transmission tower damages are destruction and/or inclination in some cases due to foundation damages following ground deformation and/or landslide, and insulator damages and/or cable cutting, short-circuiting in other cases. There were many damages on supporting insulators, lightning arresters and the inclinations of gas circuit breakers as a whole due to ground deformation at the Chungliau Switchyard which is located at the pivot of the electric transmission route from south part of Taiwan to north. It is said to take about a year for its complete restoration. The damages at hydropower plants and at Taichung coal thermal power plant, which is one of the largest in Taiwan, are, generally speaking, slight. But Shihkang Dam for irrigation collapsed which was directly hit by the earthquake surface fault.

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