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通常认为古登堡—里克特关系式中的b值反映了地壳的应力状态;因此,b值在时空上的变化能为地壳构造提供重要的信息。我们研究了选自南加州的7个区域的b值随深度的变化。之前有研究详细地描绘了加州地区b值随深度的变化图,而我们的研究没有如此系统化。我们的方法与Mori和Abercrombie应用在局部区域的方法很相似。与之前的一些研究相比,我们的研究表明,b值的变化在统计上并不显著,b值随着深度的增加而减小的这一现象应慎重解释。我们采用的地震目录是由南加州地震台网(SCSN)记录并由Richards-Dinger和Shearer重定位的100000个地震事件中的子事件。在比较b值差异时,我们通过与自助检验法的比对研究了宇津检验法(Utsustest)的特性。我们的研究结果也对宇津检验法在比较b值差异时的相关性提出疑问。模拟结果和真实数据都显示出宇津检验法倾向于反驳零假设,更认同b值是显著不同的假设。
The b value in the Gutenberg-Richter relation is generally considered to reflect the stress state of the crust; therefore, the temporal and spatial variation of b can provide important information for crustal tectonics. We studied the b value with depth variation in seven regions selected from Southern California. Previous studies have described in detail the b-value versus depth map of California, and our research has not been systematized. Our approach is very similar to the method used by Mori and Abercrombie in local areas. Compared with some previous studies, our research shows that the change of b value is not statistically significant, and the phenomenon of b value decreasing with depth should be carefully explained. The seismic catalog we use is a subset of the 100,000 earthquake events recorded by the Southern California Seismic Network (SCSN) and relocated by Richards-Dinger and Shearer. When comparing b-value differences, we examined the properties of the Utsu’s test by comparison with self-test methods. Our findings also raise questions about the relevance of the Ujin test when comparing b-value differences. Both the simulation results and the real data show that Utsunism tends to counter the null hypothesis and more strongly assigns the b-value to a significantly different hypothesis.