The 2022 Mw6.2 Pasaman earthquake took place in central-west Sumatra in association with activity in the Sumatran Fault system. This study clarifies the spatial and temporal distribution of the Pasaman earthquake sequence and forecasts the earthquake sequence’s impact on the seismicity in the vicinity and in the Sumatran Fault system. We first examined the seismicity before the mainshock and observed temporal low b-value anomalies, shedding light on the earthquake’s precursor by monitoring b-values prior to the event. Based on the aftershocks in the first 18 days, we modeled the temporal distribution of the aftershocks according to the modified Omori’s law, which suggested this sequence could last 49–473 days. By further considering Båth’s law and the Gutenberg–Richter law, we estimated the temporal distribution of the maximum magnitudes in the aftershock sequence. To understand the spatial pattern of the aftershocks, we calculated the coseismic Coulomb stress change imparted by the Pasaman mainshock. Considering uncertainties of the Coulomb stress calculations from rupture geometry, mainshock parameters, friction coefficients, and strike angles of the receiver plane, the patterns of the Coulomb stress changes are similar that the stress increases extended northwest and southeast, consistent with aftershock distribution. We further evaluated rupture probability for each segment of the Sumatran Fault. Considering the stress perturbation imparted by the Pasaman earthquake, we expected a seismicity rate increase of ca. 40% at the Sumpur and Sianok segments in the short term. To quantify long-term rupture probability, the recurrence interval and the time elapsed since the previous earthquake were incorporated based on the time-dependent Brownian passage-time model. The earthquake probability at the Sumani segment in the coming 50 years was determined to be 72%. The results of this study have significant implications for subsequent probabilistic seismic hazard assessments, not only for Sumatra but also for certain metropolitan areas in Malaysia and Singapore.

中文翻译：

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2022 Mw6.2 Pasaman, Indonesia, 地震序列及其对中西部苏门答腊地震危险性的启示

2022 年 Mw6.2 帕萨曼地震发生在苏门答腊中西部，与苏门答腊断层系统的活动有关。本研究阐明了帕萨曼地震序列的时空分布，并预测了地震序列对附近地区和苏门答腊断层系统地震活动的影响。我们首先检查了主震前的地震活动并观察了时间上的低 b 值异常，通过监测事件前的 b 值揭示了地震的前兆。根据前 18 天的余震，我们根据修正的大森定律模拟了余震的时间分布，这表明该序列可能持续 49-473 天。通过进一步考虑巴斯定律和古腾堡-里希特定律，我们估计了余震序列中最大幅度的时间分布。为了了解余震的空间模式，我们计算了帕萨曼主震产生的同震库仑应力变化。考虑到库仑应力计算的破裂几何形状、主震参数、摩擦系数和接收面走向角等方面的不确定性，库仑应力变化模式类似，应力增加向西北和东南方向延伸，与余震分布一致。我们进一步评估了苏门答腊断层每一段的破裂概率。考虑到帕萨曼地震带来的应力扰动，我们预计地震活动率将增加约 10 倍。短期内 Sumpur 和 Sianok 细分市场为 40%。为了量化长期破裂概率，基于时间相关的布朗通道时间模型，将复发间隔和自上次地震以来经过的时间结合起来。未来 50 年 Sumani 段的地震概率被确定为 72%。这项研究的结果对随后的地震概率概率评估具有重要意义，不仅对苏门答腊岛而且对马来西亚和新加坡的某些大都市地区也是如此。