中南阿拉斯加地震特征分析

Analysis of the earthquake characteristics in Southcentral Alaska

地震对当地地质地貌的塑造具有很大的作用,通过研究阿拉斯加中南部的地震特征有助于进一步了解中南阿拉斯加的地质构造。在梳理重要地震及其相关知识的前提下,对阿拉斯加中南部地区的地震特征进行了分析。指出:(1)中南阿拉斯加的地震频繁且常常能量巨大,太平洋板块俯冲及其向形成阿拉斯加南部的地体上施加的压力是促成中南阿拉斯加发生地震的原因;(2)发生在1964年的美好星期五大地震的震中位于威廉王子湾北部的阿奈奎克湾东岸的地下,瓦尔迪兹以西大约40英里的地方,地面大约12英里以下的浅源区,这次地震的震级为里氏9.2级。在这次大地震中,不同的位置发生了不同的沉降和隆升,这种规模的地震在中南阿拉斯加平均大约每600~950a会发生一次;(3)德奈利断层是个平移断层,断层的一盘相对于另一盘做平移移动。发生在2002年的德奈利断层大地震记录到的震级为里氏7.9级,在门塔斯塔湖和帕克森之间的断层附近,地面水平位移达到最大,为29英尺。此次地震只发生在3英里多一点的深度,是北美洲对地面破坏最严重的地震,这种规模的地震再经过600a的扭力积聚后还会发生。

Earthquake plays an important role on shaping the local geological landscape. Studying earthquake characteristics in Southcentral Alaska can help further understand its geological structure. The paper analyzes the earthquake characteristics in Southcentral Alaska on the basis of combing important earthquake and its related knowledge. It points out： （1）Earthquakes in Southcentral Alaska are frequent and often powerful. Southcentral Alaska＇s earthquakes are a result of the subduction of the Pacific Plate and the pressure it exerts non the terranes that form southern Alaska; （2）The epicenter of the 1964 good Friday earthquake was underneath the east shore of Unakwik Inlet in northern Prince William Sound, about miles west of Valdez, at a shallow depth of about 12 miles. The earthquake of magnitude 9. 2 on the Richter scale. In this earthquake, different locations have taken place different subsidence and uplift. An earthquake of this scale occurs in Southcentral Alaska on average about every 600 to 950 years; （3）The Denali Fault is a transform fault, where one section of plate moves laterally compared to another. The 2002 Denali Fault earthquake registered 7.9 on the Richter scale. The maximum horizontal ground displacement was 29 feet, near the fault between Mentasta Lake and Paxson. The earthquake occurred a little more than 3 miles deep and it was the largest earthquake to strike on land in North American. Evidence suggests that an event of this magnitude occurs after a build-up of strain for 600 years.