Apparent break in earthquake scaling due to path and site effects on deep borehole recordings
Apparent break in earthquake scaling due to path and site effects on deep borehole recordings
复制标题
DOI：
10.1029/2001jb001617
复制
发表时间：
2003-05-24
影响因子：
3.9
通讯作者：
Ellsworth, WL
中科院分区：
文献类型：
--
作者：
Ide, S;Beroza, GC;Ellsworth, WL
[1]我们重新检查的应力降和视应力，刚度倍的地震辐射能量与地震矩之间的比率，与地震规模的一组微震记录在长谷，加州的深井的比例。在第一组计算中，我们假设Q为常数，并求解转角频率和地震矩。在第二组计算中，我们对附近事件的光谱比进行建模，以确定相同的量。我们发现，光谱比技术，它可以占路径和网站的影响或非常数Q，产生更高的应力下降，特别是对于较小的事件在数据集中。从光谱比确定的测量表明，在我们的数据集（M-W 0.8）中，按比例缩小到最小事件的恒定应力降没有偏离。我们的研究结果表明，传播效应可以污染源参数的测量，即使在相对干净的记录环境的深钻孔，就像他们在地球表面。从深钻孔记录中获得的微地震源特性的标度可能需要重新评估。
[1] We reexamine the scaling of stress drop and apparent stress, rigidity times the ratio between seismically radiated energy to seismic moment, with earthquake size for a set of microearthquakes recorded in a deep borehole in Long Valley, California. In the first set of calculations, we assume a constant Q and solve for the corner frequency and seismic moment. In the second set of calculations, we model the spectral ratio of nearby events to determine the same quantities. We find that the spectral ratio technique, which can account for path and site effects or nonconstant Q, yields higher stress drops, particularly for the smaller events in the data set. The measurements determined from spectral ratios indicate no departure from constant stress drop scaling down to the smallest events in our data set (M-w 0.8). Our results indicate that propagation effects can contaminate measurements of source parameters even in the relatively clean recording environment of a deep borehole, just as they do at the Earth's surface. The scaling of source properties of microearthquakes made from deep borehole recordings may need to be reevaluated.