Closing crack earthquakes within the Krafla caldera, North Iceland
Closing crack earthquakes within the Krafla caldera, North Iceland
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DOI：
10.1093/gji/ggw325
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发表时间：
2016-11
影响因子：
2.8
通讯作者：
Zo¨e K. Mildon;Gji Seismology;Zo¨e K. Mildon;D. Pugh;J. Tarasewicz;R. White;Brynd´ıs Brandsd´ottir
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文献类型：
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作者：
Zo¨e K. Mildon;Gji Seismology;Zo¨e K. Mildon;D. Pugh;J. Tarasewicz;R. White;Brynd´ıs Brandsd´ottir
矩张量分析与贝叶斯方法被用来分析一个非双力偶（非DC）地震（MW 1.1）与高各向同性（内爆）组成部分内的Krafla火山口，冰岛。我们推断地震是由深部闭合裂缝引起的。该地震位置好，信噪比高，在所有台站都显示出明显的P波初至，初至可以有把握地拾取。焦球的覆盖范围是全面的，源机制在所有不确定性范围内都是稳定的。非DC事件位于包括许多DC事件的微震活动簇内。因此，我们认为这是一次真正的非直流闭合裂缝地震，是地热利用和目前在该地区观测到的岩浆房收缩的结果。
Moment tensor analysis with a Bayesian approach was used to analyse a non-double-couple (non-DC) earthquake (Mw ∼ 1) with a high isotropic (implosive) component within the Krafla caldera, Iceland. We deduce that the earthquake was generated by a closing crack at depth. The event is well located, with high signal-to-noise ratio and shows dilatational P-wave first arrivals at all stations where the first arrival can be picked with confidence. Coverage of the focal sphere is comprehensive and the source mechanism stable across the full range of uncertainties. The non-DC event lies within a cluster of microseismic activity including many DC events. Hence, we conclude that it is a true non-DC closing crack earthquake as a result of geothermal utilization and observed magma chamber deflation in the region at present.