Microseismicity but no tremor accompanying slow slip in the Hikurangi subduction zone, New Zealand
Microseismicity but no tremor accompanying slow slip in the Hikurangi subduction zone, New Zealand
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DOI：
10.1016/j.epsl.2008.09.038
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发表时间：
2009-01-15
影响因子：
5.3
通讯作者：
Rogers, G.
中科院分区：
文献类型：
--
作者：
Delahaye, E. J.;Townend, J.;Rogers, G.
在几个俯冲带中，经大地测量检测到的慢滑事件都伴随着被称为地震震颤的低频相干噪声的爆发，但是否有一个单一的物理过程控制着这种联系，甚至是否慢滑总是伴随着震颤，这些问题仍未得到解决。对新西兰Hikurangi俯冲带慢滑事件的宽带地震数据的详细分析表明，慢滑伴随着明显的逆断层微地震，而不是震颤。这些地震的时间、位置和断裂类型与应力触发慢滑块的下倾一致，要么在俯冲界面上，要么就在它的下方。这些结果表明，在俯冲带慢滑过程中，地震并不普遍存在，而在俯冲带的慢滑环境中，有可能引发闭锁俯冲逆冲基底附近的高频地震。在这个和其他地方（夏威夷，波索半岛），缓慢滑动伴随着触发的微地震活动，估计的缓慢滑动的上范围较浅（小于类似的20公里），比那些已经报道震颤的地方。这表明，环境温度或压力相关因素控制着俯冲逆冲和其他大断层慢滑动的地震响应特征，浅层的流变或岩性条件触发高频微地震，而深层的流变或岩性条件触发地震震颤。(c) 2008 Elsevier B.V.版权所有
Geodetically-detected episodes of slow slip appear in several subduction zones to be accompanied by bursts of low-frequency, coherent noise known as seismic tremor, but whether a single physical process governs this association or even whether slow slip is invariably accompanied by tremor remains unresolved. Detailed analysis of broadband seismic data spanning a slow slip episode in the Hikurangi subduction zone, New Zealand, reveals that slow slip was accompanied by distinct reverse-faulting microearthquakes, rather than tremor. The timing, location, and faulting style of these earthquakes are consistent with stress triggering down-dip of the slow slip patch, either on the subduction interface or just below it. These results indicate that tremor is not ubiquitous during subduction zone slow slip, and that slow slip in subduction zone environments is capable of triggering high-frequency earthquakes near the base of the locked subduction thrust. In this and other locations (Hawaii, Boso Peninsula) where slow slip is accompanied by triggered microseismicity, the estimated upper extent of the slow slip is shallower (less than similar to 20 km) than in those locations from which tremor has been reported. This suggests that ambient temperature- or pressure-dependent factors govern the character of the seismic response to slow slip on subduction thrusts and other large faults, with rheological or lithological conditions at shallow depths triggering high-frequency microearthquakes and those at greater depths triggering seismic tremor. (c) 2008 Elsevier B.V. All rights reserved.