Department of Civil Engineering, Universidad Católica de la Santísima Concepción, Concepción, Chile.
Department of Geophysics, Universidad de Concepción, Concepción, Chile.
Sci Rep. 2022 Dec 15;12(1):21710. doi: 10.1038/s41598-022-25338-4.
The b-value can be used to characterize the seismic activity for a given earthquake catalog and provide information on the stress level accumulated at active faults. Here we develop an algorithm to objectively estimate variations of b-value along one arbitrary dimension. To this end, we employ a Bayesian transdimensional approach where the seismic domains will be self-defined according to information in the seismic catalog. This makes it unnecessary to prescribe the location and extent of domains, as it is commonly done. We first show the algorithm's robustness by performing regressions from synthetic catalogs, recovering the target models with great accuracy. We also apply the algorithm to a microseismicity catalog for the Central Chile region. This segment is considered a seismic gap where the last major earthquake with shallow slip was in 1730. Our results illuminate the downdip limit of the seismogenic zone and the transition to intraslab seismicity. In the along-strike direction, low b-value coincides with the extent of locked asperities, suggesting a high-stress loading at the Central Chile seismic gap. Our results indicate the reliability of the Bayesian transdimensional method for capturing robust b-value variations, allowing us to characterize the mechanical behavior on the plate interface of subduction zones.
b 值可用于描述给定地震目录中的地震活动，并提供有关活动断层上积累的应力水平的信息。在这里，我们开发了一种算法来客观估计沿任意一维 b 值的变化。为此，我们采用贝叶斯跨维方法，根据地震目录中的信息自动定义地震域。这使得我们不必像通常那样规定域的位置和范围。我们首先通过从合成目录中执行回归来展示算法的稳健性，非常准确地恢复目标模型。我们还将该算法应用于智利中部的微震目录。该段被认为是地震空白区，上次浅层滑动的主要地震发生在 1730 年。我们的结果照亮了发震区的下游极限和向板内地震活动的转变。在走向方向上，低值 b 与锁定asperity 的范围一致，表明智利中部地震空白区的高应力加载。我们的结果表明贝叶斯跨维方法用于捕捉稳健 b 值变化的可靠性，使我们能够描述俯冲带板块界面的力学行为。
