In Probabilistic Seismic Hazard Analysis (PSHA), a widely used approach to model earthquake sources consists of using homogenous source zones. This approach suffers the limitation of assuming that the observed seismicity can occur anywhere with same probability over a specific area, which might lead to the potential undervaluation of the predicted ground motion level due to an effect of smearing of seismic potential. To compensate that, a hybrid model is used, accounting both for distributed seismicity and localized seismogenic structures.

In this study, we perform PSHA for Northeast India and Bhutan, that are the most seismically hazardous regions on the planet. The region was partitioned into seismogenic source zones of supposedly homogeneous seismic potential and seismotectonic characteristics. Earthquake recurrence parameters for each zone were obtained from direct magnitude-frequency analysis on a precompiled global catalogue. Seismogenic faults are added to the model by converting slip rates from GPS velocity data to seismic activity. Complementary information was derived from the analysis of moment tensor solutions of large events and from a detailed literature review.

Using this hybrid model, seismic hazard was calculated for a region bounded by lat/long 24.0°-28.8°N/88.0°-94.5°E. Calculations were performed for Peak Ground Acceleration (PGA) and several Spectral Acceleration (SA) periods for a Probability of Exceedance (POE) of 10% in 50 years, corresponding to 475 years return period, and for a reference rock condition with Vs = 800 m/s. The results highlight significant acceleration levels (about 0.77g at PGA) in the Arunachal Pradesh region (Northeast India), due to the presence of the Himalayan Frontal Thrust (HFT).

在概率地震危害分析 (PSHA) 中，一种广泛使用的模拟地震源的方法包括使用同质震源区。这种方法的局限性在于假设观测到的地震活动可以在特定区域内以相同的概率发生在任何地方，这可能会由于地震潜力的涂抹效应而导致对预测的地震动水平的潜在低估。为了弥补这一点，使用了混合模型，同时考虑了分布式地震活动和局部发震结构。

在这项研究中，我们对印度东北部和不丹进行了 PSHA，这两个地区是地球上地震最危险的地区。该地区被划分为具有均一地震潜力和地震构造特征的地震源区。每个区域的地震复发参数是通过对预编译的全球目录的直接震级频率分析获得的。通过将 GPS 速度数据的滑动率转换为地震活动，将发震断层添加到模型中。补充信息来自对大型事件的矩张量解的分析和详细的文献综述。

使用此混合模型，计算了以纬度/经度 24.0°-28.8°N/88.0°-94.5°E 为界的区域的地震危险性。计算了峰值地面加速度 (PGA) 和几个光谱加速度 (SA) 周期，50 年内超过 10% 的概率 (POE)，对应于 475 年的重现期，以及 Vs = 800 的参考岩石条件多发性硬化症。由于喜马拉雅正面推力 (HFT) 的存在，结果突出显示了阿鲁纳恰尔邦地区（印度东北部）的显着加速水平（PGA 处约为 0.77g）。