• 作者： 廖政賢; 王正松; 廖滄龍
• 作者服務機構： 中央研究院地球科學研究所
• 中文摘要： 中央研究院地球科學研究所於民國74年6月14日至8月20日期間，在臺灣東部（北從和平村，南至臺束）設有一個由十七個測震站組成的臨時測震網，以瞭解臺灣東部地區之地震特性。本文分析由此測震網所定的579個位於測震網內及其附近且定位較佳之地震的空問分佈，並將探討其與大地構造之關係。 臺灣東部海岸線兩側各約35公里範圍之內地震頻繁。都巒山斷層東側和鳳林附近地震最為活躍，但海岸山脈介於玉里和瑞穗之間地震極少。曾造成災害的玉里地震（民國40年；規模7．1)和瑞穗地震（民國61年；規模6．6)所產生的地表斷層即分佈於此地震極少區之西側和北側，因此，此兩地震與此地震極少區有相當關連。 太魯閣變質岩帶及其西邊之地震，除了鳳林附近者外，大部份分佈於0-20公里的深度。玉里變質岩帶西界至臺東縱谷之地震大致分佈於兩個深度層（0-20公里及30-60公里）。玉里變質岩帶西界以東至海域之地震形成一個厚度向北逐漸加大的地震帶。此地震帶厚度於臺東附近約為40公里，而於花蓮附近約為60公里。位於此地震帶之規模大於3之地震分佈於0-20公里及40-60公里兩層，下層之地震全部在此地震帶底面附近。因此，此地震帶底面可能代表一個震波不連續面。由上述可知，玉里變質岩帶西界和臺東縱谷區分三個特性不同的地震帶，因此，於大地構造上具有特殊意義。
• 英文摘要： A temporary seismic network consisting of seventeen stations and covering an area from Hopingtsun(to the north of Hualien) to Taitung was in operation in eastern Taiwan from June 14 to August 20, 1985．In this paper, we analyze the spatial distribution of the well-located earthquakes which were within or nearthis network. The main purpose is to study the characteristics of the seismicity and its relationship to thetectonics in the eastern Taiwan area. The neighborhood of the eastern coastal line is seismically very active; the epicenters are mainly in azone with a width of some 70 km. There are apparent epicenter concentrations near the Tuluanshan faultat 23°N and near Fenglin and an earthquake rarity in the section of the Coastal Range between Juisui andYuli. The destructive 1951 Yuli and 1972 Juisui earthquakes (with magnitudes of 7.1 and 6.6，respectively)are probably associated with this earthquake rarity. The hypocentral distribution shows that the boundary between the Yuli and the Tailuko metamor-phic belts (the YT boundary) and the Longitudinal Valley separate three seismic belts of different charac-teristics. The hypocenters west of the YT boundary are mainly shallower than 20 km. Those between theYT boundary and the Longitudinal Valley are mainly in two depth ranges: 0-20 km and 30-60 km, butthose east of the Longitudinal Valley have no such clear stratification. Therefore, the YT boundary and theLongitudinal Valley are important in the plate tectonics of Taiwan region. The hypocenters east of the YT boundary to the eastern offshore area show a seismic zone graduallythickening toward the north. The thickness is about 40 km near Taitung and about 60 km near Hualien.Furthermore, about all the earthquakes with magnitude greater than 3 in this seismic zone are in two depthranges：0-20 km and 40-60 km，and those in the lower depth range are located near the bottom of theseismic zone. Therefore, a bottom boundary of the seismic zone clearly exists, which may represent a ve-locity discontinuity in the eastern Taiwan area.
• 中文關鍵字： seismicity; tectonlcs
• 英文關鍵字： --