Correlations of Seismicity Patterns in Southern California with Surface Heat Flow Data
Correlations of Seismicity Patterns in Southern California with Surface Heat Flow Data
复制标题
南加州地震活动模式与地表热流数据的相关性
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Y. Ben‐Zion
中科院分区：
文献类型：
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作者：
B. Enescu;S. Hainzl;Y. Ben‐Zion
我们使用重新定位的地震目录研究了南加州地震活动图像的性质与地表热流之间的关系。我们首先搜索地震序列，以及从其他地震活动的时间和空间分离，然后确定流行型余震序列（ETAS）模型参数的序列与足够数量的事件。我们关注ETAS模型的生产率参数α，该参数量化了M级地震产生余震的相对效率。通过分别叠加α值相对较小和相对较大的序列，我们观察到两组之间存在明显差异。α较小的序列前震数相对较多，余震数相对较少.相比之下，α较大的较典型序列的前震相对较少，余震数量较多。较典型的后一序列的叠加震前活动在主震发生的前一天有明显的增加。α值的空间分布与地表热流有较好的相关性：高热流区α值相对较小，表明在这些地区震群型地震活动较为普遍。我们的研究结果是兼容的损伤流变模型，预测群型地震活动的地区相对较高的热流和更典型的前震-主震-余震序列的地区正常或低的地表热流。在具有高或低热流值的区域中，α的高度可变性表明，在局部尺度上，流体含量和岩石类型）可能影响地震活动生成过程。
We investigate the relations between properties of seismicity patterns in Southern California and the surface heat flow using a relocated earthquake catalog. We first search for earthquake sequences that are well separated in time and space from other seismicity and then determine the epidemic type aftershock sequence (ETAS) model parameters for the sequences with a sufficient number of events. We focus on the productivity parameter α of the ETAS model that quantifies the relative efficiency of an earthquake with magnitude M to produce aftershocks. By stacking sequences with relatively small and relatively large α values separately, we observed clear differences between the two groups. Sequences with a smaller α have a relatively large number of foreshocks and relatively small number of after- shocks. In contrast, more typical sequences with larger α have relatively few fore- shocks and larger number of aftershocks. The stacked premainshock activity for the more typical latter sequences has a clear increase in the day before the occurrence of the main event. The spatial distribution of the α values correlates well with the surface heat flow: areas of high heat flow are characterized by relatively small α, indicating that in such regions the swarm-type earthquake activity is more common. Our results are compatible with a damage rheology model that predicts swarm-type seismic activity in areas with relatively high heat flow and more typical foreshock- mainshock-aftershock sequences in regions with normal or low surface heat flow. The high variability of α in regions with either high or low heat flow values indicates that at local scales additional factors (e.g., fluid content and rock type) may influence the seismicity generation process.