宜蘭地區地震帶與震源參數之評估

Assessment of Seismic Source Zones and Related Source Parameters in the Ilan Area, Taiwan

黃宏謀(Howard Hwang) ； 許智豪(Chih-Hao Hsu) ； 陳國誠(Kou-Cheng Chen)

《國立宜蘭大學工程學刊》 3期 (2007/02) Pp. 57-68

https://doi.org/10.6176/BCE.2007.03.15

摘要

本研究之目的為探討宜蘭地區的地震活動情形，定出可能的地震帶與震源參數。本研究根據宜蘭地區1900-2005年間震源深度淺於35公里地震震央分佈的狀況，決定出可能影響宜蘭地區之五個地震帶，分別為沖繩海槽地震A段、沖繩海槽地震帶B段、蘇澳地震帶、蘇澳花蓮近海地震帶及蘇澳花蓮外海地震帶。本研究也訂定斷層參數，包括斷層種類、斷成長度及斷層開裂方位角。在防災應變策略上，通常會用最大的地震來進行災損境況模擬，因此本研究利用斷層總長度來求得在此地震帶可能發生的最大震矩規模與芮氏規模，並且利用歷史地震來決定震源深度。本研究也說明當震源為線震源或點震源時，地表振動強度計算的方法，並舉一個例子說明計算的過程。本研究之成果將可利用來進行災損境況模擬，評估建築物可能受到的損害，進而估計可能的人員的傷亡與經濟損失。這些成果可以用來訂定出有效的防災與減災的對策。

關鍵字

斷層 ； 地震帶 ； 震源參數 ； 地表振動強度

並列摘要

In this study, we determine seismic source zones and source parameters in the Yi-lan area. First, we investigate seismic activity around the Yi-lan area based on the seismic data in the time period of 1900 to 2005. From the distribution of epicenters, we identify five seismic source zones, which include Okinawa trough seismic zone section. A, Okinawa trough seismic zone section B, Suao seismic zone, Sauao-Hualien near shore seismic zone and Sauao-Hualien sea seismic zone. We consider these seismic zones as line faults and determine fault parameters, such as fault, types, fault length and fault azimuth. In seismic hazards mitigation strategy, we usually use a maximum earthquake to perform scenario simulation. In this study, we determine the moment magnitude and Richter magnitude based on the total length of a fault; we also determine the focal depth from the history earthquake. Given the occurrence of an earthquake, we estimate the intensity of ground shaking at a site based on an appropriate attenuation relation and a site modification factor. The results of this study can be used to perform simulation of seismic disaster scenario, including evaluation of damage to buildings and estimation of casualties and economic losses. These results then can be used to implement a strategy for seismic disaster reduction.

並列關鍵字

fault ； seismic zone ； source parameter ； ground shaking