Xie Weiyun, Hattori Katsumi, Han Peng, Shi Haixia
Graduate School of Science and Engineering, Chiba University, Chiba 263-8522, Japan.
Graduate School of Science, Chiba University, Chiba 263-8522, Japan.
Entropy (Basel). 2022 Mar 31;24(4):494. doi: 10.3390/e24040494.
The Gutenberg-Richter b value describes the ratio between large and small events. A number of studies have suggested that the b value decreases before large earthquakes. In this study, we investigate the temporal variation of the b value of an area along the main rupture zone of the 2008 Wenchuan earthquake (M8.0) prior to the great event. Before estimating b values, we tested the earthquake catalog to make sure that we use the reliable frequency-magnitude distribution by the calculation of MC (completeness of magnitude). We define parameter P (ΔAIC ≧ 2) values to examine the significance level of b-value changes in the temporal variation by combining a boostrap method with Akaike's Information Criterion (AIC). The b value in the main rupture zone shows a long-term decrease trend. We then focus on a smaller area where the initial rupture starts. The results show that b values significantly changed about 3 months before the 2008 Wenchuan earthquake in the initial rupture area, indicating that the b value has a potential capability to monitor and detect precursory phenomena of great earthquakes.
古登堡-里希特b值描述了大小地震之间的比率。许多研究表明，大地震发生前b值会降低。在本研究中，我们调查了2008年汶川地震（M8.0）主破裂带沿线一个区域在大地震发生前b值的时间变化。在估计b值之前，我们对地震目录进行了检验，通过计算震级完整性（MC）来确保我们使用的是可靠的频震分布。我们通过将自助法与赤池信息准则（AIC）相结合来定义参数P（ΔAIC≧2）值，以检验b值在时间变化中变化的显著性水平。主破裂带的b值呈现长期下降趋势。然后我们聚焦于初始破裂开始的一个较小区域。结果表明，在2008年汶川地震前约3个月，初始破裂区域的b值发生了显著变化，这表明b值具有监测和检测大地震前兆现象的潜在能力。
