A Tremor and Slip Event on the Cocos-Caribbean Subduction zone as measured by a GPS and Seismic Network on the Nicoya Peninsula, Costa Rica
A Tremor and Slip Event on the Cocos-Caribbean Subduction zone as measured by a GPS and Seismic Network on the Nicoya Peninsula, Costa Rica
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哥斯达黎加尼科亚半岛 GPS 和地震台网测量的科科斯-加勒比俯冲带地震和滑动事件
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发表时间：
2010
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影响因子：
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通讯作者：
W. Rabbel
中科院分区：
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作者：
Kimberly C. Outerbridge;T. Dixon;S. Schwartz;J. Walter;M. Protti;V. González;Juliet Biggs;Juliet Biggs;M. Thorwart;W. Rabbel
2007年5月，哥斯达黎加北部尼科亚半岛的全球定位系统(GPS)和地震台网络记录了一次伴随着地震的慢滑事件。尼科亚半岛靠近科科斯-加勒比俯冲板块边界的地震孕育部分，这使其成为研究此类事件的好地点。GPS台站在几天到几周的时间里记录了几厘米的西南运动，而地震台在同一时间段记录了三次不同的震动。对板块界面滑动深度和滑动方式的地表位移数据进行了反演，结果表明，在25-30公里深度处有滑动峰值，这是主要孕震带的下倾。据估计，这里的温度为∼250°-300°C，低于此前已发现此类事件的其他俯冲带。在∼6公里深也可能有一块较浅的滑移。这些结果具有重要意义，因为它们首次表明，在从粘滑到稳定滑动的上倾角转变过程中，可以发生慢滑，并且慢滑不需要临界温度门槛。地震和低频地震的位置更难确定。我们的结果表明，它们发生在与深部慢滑相同深度范围的板块界面上或附近，但在空间上不是同一位置。
In May 2007 a network of global positioning systems (GPS) and seismic stations on the Nicoya Peninsula, of northern Costa Rica, recorded a slow-slip event accompanied by seismic tremor. The close proximity of the Nicoya Peninsula to the seismogenic part of the Cocos-Caribbean subduction plate boundary makes it a good location to study such events. Several centimeters of southwest motion were recorded by the GPS stations over a period of several days to several weeks, and the seismic stations recorded three distinct episodes of tremor during the same time span. Inversion of the surface displacement data for the depth and pattern of slip on the plate interface shows peak slip at a depth of 25–30 km, downdip of the main seismogenic zone. Estimated temperatures here are ∼250°–300°C, lower than in other subduction zones where events of this nature have been previously identified. There may also be a shallower patch of slip at ∼6 km depth. These results are significant in that they are the first to suggest that slow slip can occur at the updip transition from stick slip to stable sliding, and that a critical temperature threshold is not required for slow slip. Tremor and low-frequency earthquake locations are more difficult to determine. Our results suggest they occur on or near the plate interface at the same depth range as the deep slow slip, but not spatially colocated.