Sub-crustal earthquakes within the Australia–Pacific plate boundary zone beneath the Southern Alps, New Zealand
Sub-crustal earthquakes within the Australia–Pacific plate boundary zone beneath the Southern Alps, New Zealand
复制标题
新西兰南阿尔卑斯山下方澳大利亚-太平洋板块边界带内的地壳下地震
DOI：
10.1016/j.epsl.2013.06.030
复制
发表时间：
2013
影响因子：
5.3
通讯作者：
Euan Smith
中科院分区：
文献类型：
--
作者：
C. Boese;C. Boese;T. Stern;John Townend;S. Bourguignon;A. Sheehan;Euan Smith
在新西兰南岛中部，近40年来一直零星地观测到地壳下地震。我们报告了2008年12月至2012年2月期间在澳大利亚和太平洋板块之间的大陆碰撞带阿尔卑斯断层附近记录的20起事件。在47-74公里深处的18个事件的子集发生在山以南。库克和最近报道的地震位置表明，沿走向变化的变形行为沿着板块边界。山以南的次地壳地震。库克增加的深度，频率和规模向南走向Puysegur俯冲带。可以确定14个地震的震源机制，并表现出主要的走滑和逆断层的解决方案。震源机制的应力反演分析产生了一个应力场有利于逆冲断层。我们解释了这些地壳下事件的地理和垂直分布关系到以前提出的构造模型的残余被动边缘，新西兰南部的始新世，并被推翻时，右旋走滑运动开始在阿尔卑斯山断层。我们推断，地壳下地震发生沿着前缘的结构，这是连接到大陆澳大利亚地壳。
Sub-crustal earthquakes have been observed sporadically for ∼40 years in the central South Island of New Zealand. We report on 20 events recorded between December 2008 and February 2012 near the Alpine Fault in the continental collision zone between the Australian and Pacific plates. A subset of 18 events at depths of 47–74 km occurs south of Mt. Cook and together with recently reported tremor locations indicates along-strike variations in deformation behaviour along the plate boundary. The sub-crustal earthquakes south of Mt. Cook increase in depth, frequency and size southwards towards the Puysegur subduction zone. Focal mechanisms could be determined for 14 earthquakes and exhibit predominantly strike-slip and reverse faulting solutions. Stress inversion analysis of the focal mechanisms yields a stress field favouring oblique-reverse faulting. We interpret the geographic and vertical distributions of these sub-crustal events in relation to a previously proposed tectonic model of a remnant passive margin that formed south of New Zealand in the Eocene and was overridden when dextral strike-slip motion initiated on the Alpine Fault. We infer that sub-crustal earthquakes occur along the leading edge of this structure, which is attached to the continental Australian crust.