Abstract The study interprets the effect of seasonal (pre-, co- and post-monsoon) hydrological loading due to the Ganga river basin over the seismicity and geodetic deformation in the Garhwal Himalayan region. Geodetic data from six cGPS sites are used, three sites out of six are established in the Himalayan region, one is located in the Ganga basin and two sites are located in the Indian shield. First, we estimated the average seasonal variation in GRACE-derived TWS of entire India for the period of 2002–2016. It is observed the seasonal effect over TWS (Terrestrial Water Storage) due to hydrological fluctuations in the Indo-Gangetic Plain (IGP). It has also been noticed that the geodetic velocities for both the North and East components are more in pre-monsoon than post-monsoonal season. Whereas the vertical component in cGPS sites of Himalaya (DEHR and MAND) agrees to the hypothesis of upliftment during post-monsoon and subsidence in pre-monsoon. TWS mass change is detected high during the co-monsoon (2.32 × 104 km3) and it is observed low −2.22 × 104 km3 (in pre-) and −8.13 × 103 km3 (in post-) monsoon seasons respectively. GPS measured horizontal displacement agrees with seasonal loading but it contains some anomalous behaviour, which may be the result of surface hydrological mass movement or the effect of the Gorkha earthquake, 2015, however an inverse relation between vertical geodetic displacement and loading have been observed. The average strain rate values over cGPS sites during 2016–2018, are more negative in post-monsoon than in pre-monsoon which means that plate movement is highly compressional. We have also inferred a significant role of loading over the seismicity and linear strain rate, which increases with decreasing hydrological loading in the Ganga river basin and vice versa.

中文翻译：

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喜马拉雅西北加瓦尔地区季节性水文负荷对地震活动和大地变形变化的贡献

摘要 本研究解释了由恒河流域引起的季节性（季风前、季风后和季风后）水文负荷对 Garhwal 喜马拉雅地区地震活动和大地测量变形的影响。使用了来自六个 cGPS 站点的大地测量数据，六个站点中的三个站点位于喜马拉雅地区，一个位于恒河盆地，两个站点位于印度地盾中。首先，我们估计了 2002-2016 年整个印度 GRACE 衍生的 TWS 的平均季节性变化。观察到由于印度恒河平原 (IGP) 的水文波动对 TWS（陆地储水）的季节性影响。还注意到，北部和东部部分的大地速度在季风前多于季风后季节。而喜马拉雅 cGPS 站点（DEHR 和 MAND）的垂直分量与季风后上升和季风前下沉的假设一致。在共同季风 (2.32 × 104 km3) 期间检测到 TWS 质量变化很高，在季风季节分别观察到低 -2.22 × 104 km3（前）和 -8.13 × 103 km3（后）。GPS 测量的水平位移与季节性载荷一致，但它包含一些异常行为，这可能是地表水文质量运动或 2015 年廓尔喀地震影响的结果，但已观察到垂直大地位移与载荷之间的反比关系。2016-2018 年 cGPS 站点的平均应变率值在季风后比季风前更负，这意味着板块运动是高度压缩的。