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Seismic potential of megathrust in the Kumaun-Garhwal region of NW Himalaya: implications from geodetic and seismic strain rates
International Journal of Earth Sciences ( IF 2.3 ) Pub Date : 2021-03-30 , DOI: 10.1007/s00531-021-02023-x
Sapna Ghavri , Sridevi Jade

We analysed the geodetic and seismic strain rates for composite analysis of seismic hazard potential of the Kumaun-Garhwal region of Northwest Himalaya. The principal geodetic strain rate is estimated using plate motion measurements at 144 Global Positioning System (GPS) sites reported in past ~ 20 years in the region. A modified least square inversion approach that utilizes a distance-based scale factor on the uncertainty in the velocity data is applied to get a reliable estimate of geodetic strain rate. Results indicate extensive compression in the region with a mean rate of − 113 nano strain/year towards NNE in the Higher Himalaya. The principal seismic strain rate is calculated from the focal mechanism solutions of the earthquakes in the region using the Kostrov formulation. We analysed the geodetic strain rate together with seismic strain rate using seismicity catalogue of 50, 220 and 700 years and found that the orientation of principal strain rates are consistent with each other. However, the seismic strain rate estimated from 700 years catalogue is comparable with geodetic strain rate indicating the high accumulation of elastic strain energy in this region. Analysis of strain budget using geodetic and seismic moment rates of this region, suggest a large amount of stored strain energy of ~ 5E + 21 Nm in the past 700 years which has a potential to generate a megathrust earthquake (Mw ≥ 8) in the present scenario.



中文翻译:

喜马拉雅西北部库玛恩-加尔瓦尔地区的超大推力地震潜力:大地应力和地震应变率的影响

我们分析了大地测量和地震应变率,以对喜马拉雅西北部库马恩-加尔瓦尔地区的潜在地震危险性进行综合分析。在该地区过去20年间报告的144个全球定位系统(GPS)站点中,利用板块运动测量值估算了大地应变速率。修改后的最小二乘反演方法在速度数据的不确定性上利用基于距离的比例因子来获得大地应变率的可靠估计。结果表明,该地区在喜马拉雅山高海拔地区向NNE的平均压缩速率为-113纳秒/年。使用Kostrov公式,根据该地区地震的震源机制解计算出主要地震应变率。我们使用50、220和700年的地震活动目录分析了大地应变率和地震应变率,发现主应变率的方向相互一致。但是,从700年的目录中估算出的地震应变率与大地应变率相当,这表明该区域中弹性应变能的高积累。使用该地区的大地和地震矩速率进行的应变预算分析表明,在过去700年中,大量存储的应变能约为5E + 21 Nm,目前有可能产生特大推力地震(Mw≥8)设想。从700年目录中估算出的地震应变率与大地应变率相当,这表明该地区弹性应变能的高积累。使用该地区的大地和地震矩速率进行的应变预算分析表明,在过去700年中,大量存储的应变能约为5E + 21 Nm,目前有可能产生特大推力地震(Mw≥8)设想。从700年目录中估算出的地震应变率与大地应变率相当,这表明该地区弹性应变能的高积累。使用该地区的大地和地震矩速率进行的应变预算分析表明,在过去700年中,大量存储的应变能约为5E + 21 Nm,目前有可能产生特大推力地震(Mw≥8)设想。

更新日期:2021-03-30
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