Strong seismic coupling underneath Garhwal–Kumaun region, NW Himalaya, India

Yadav, Rajeev Kumar; Gahalaut, Vineet K.; Bansal, Anchal; Sati, S. P.; Catherine, J. K.; Gautam, Param K.; Kumar, K.G.; Rana, Naresh

doi:10.1016/j.epsl.2018.10.023

Cited by 53 publications

(31 citation statements)

References 51 publications

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“…Gahalaut et al 2017reported transients in the GPS measurements at station KUNR, which is located less than 1 km from the Tehri reservoir on a massive outcrop of phillites of the Lesser Himalaya of the Garhwal region. The reported secular motion (of *0.5 mm/yr in the Indian reference frame) at this site is consistent with the underlying locked main Himalayan thrust (Yadav et al 2019). Gahalaut et al (2017) reported that the transient deformation at the site is influenced by the reservoir filling and emptying cycles.…”

Section: Tehri Reservoir Loading Effect At a Gps Site In Garhwal Himasupporting

confidence: 79%

Anomalous transients in GPS measurements due to induced changes in local site conditions

et al. 2019

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Transients in GPS time series can occur due to post-seismic deformation, seasonal hydrological loads, sea-level changes, flood and drought conditions, excessive groundwater withdrawal and recharge, etc. We report two new cases where the application of external loading, namely, earthquake loading and surface loading due to impoundment of hydroelectric reservoir, probably altered the local hydrological conditions to cause anomalous transients in the surface displacement. In the first case, moderate shaking due to the 2015 Gorkha earthquake at Patna (Bihar, India) caused transients in ground deformation in the following 50-60 days of the earthquake which are recorded by a continuous GPS site at Patna. In the second case, impoundment of the Tehri reservoir and its seasonal variations in the Garhwal Himalaya probably altered the local hydrological conditions which is causing anomalous biannual cyclic deformation at a site KUNR, near the reservoir.

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Section: Tehri Reservoir Loading Effect At a Gps Site In Garhwal Himasupporting

confidence: 79%

Anomalous transients in GPS measurements due to induced changes in local site conditions

et al. 2019

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“…Megathrust earthquakes occur to first order on these interseismically locked patches (e.g., Loveless & Meade, ). Conversely, previously published models in the Himalayan region suggest that the MHT is nearly uniformly locked from the surface to beneath the front of the high range over a width of 100

\pm

20 km (Ader et al, ; Li et al, ; Ponraj et al, ; Stevens & Avouac, ; Sreejith et al, ; Yadav et al, ). Therefore, the MHT appears to be an anomaly with respect to subduction megathrusts worldwide.…”

Section: Introductionmentioning

confidence: 90%

Segmentation of the Main Himalayan Thrust Illuminated by Bayesian Inference of Interseismic Coupling

Zilio

Jolivet

Dinther

2020

Geophysical Research Letters

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We use a recent compilation of geodetic data of surface displacements in a fully Bayesian approach to derive a probabilistic estimate of interseismic coupling along the Main Himalayan Thrust (MHT). Our probabilistic estimate of interseismic coupling highlights four large, highly coupled patches separated by three potential barriers of low coupling. Locked patches overlap with estimated rupture areas of historical large earthquakes over the past centuries. The coincident spatial variability in coupling, seismicity, and prominent active topography suggests a structural segmentation of the MHT imposed by inherited tectonic structures from the India‐Eurasia collision. This correlation implies that inherited tectonic structures may affect how stress builds up along the MHT, thereby influencing the location and size of large Himalayan earthquakes and the growth of the mountain range.

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“…In the Himalayan subduction zone, many efforts have been made to map the spatial variations of interseismic coupling on the interface of subduction using Global Positioning System (GPS) measurements [17][18][19][20][21][22][23][24]. These published models concluded that the whole Himalaya, including the Sikkim-Bhutan segment, is characterized by a homogeneous coupling pattern with an average locking width of 100 ± 20 km.…”

Section: Gps Data Processingmentioning

confidence: 99%

Interseismic Coupling beneath the Sikkim–Bhutan Himalaya Constrained by GPS Measurements and Its Implication for Strain Segmentation and Seismic Activity

Tao

Gao

et al. 2020

Remote Sensing

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The Sikkim–Bhutan seismic gap has witnessed a long earthquake quiescence since the 1714 M7.5~8.5 earthquake. The state of stress accumulation beneath the Sikkim–Bhutan Himalaya and its spatial correlation with seismicity remains unclear due to the lack of geodetic measurements and the low levels of seismic activity. We compile Global Positioning System (GPS) measurements in southern Tibet with the available velocities in the Sikkim–Bhutan Himalaya to reveal the characteristics of strain buildup on the Main Himalayan Thrust (MHT). We correct non-tectonic hydrological loading effects in a GPS time series to accurately determine the Three-Dimensional (3D) velocities of each continuous station. Extensive GPS measurements yield convergence rates of 16.2~18.5 mm/y across the Sikkim–Bhutan Himalaya, which is quite consistent with that observed elsewhere in the Himalaya. Based on a double-ramp structure of the MHT, a refined 3D coupling image is inverted using a dense network of GPS velocities. The result indicates significant along-strike variations of fault coupling beneath the Sikkim–Bhutan Himalaya. The locking width (coupling > 0.5) of western Bhutan reaches ~100 km, which is 30~40% wider than Sikkim and eastern Bhutan. An obvious embayment of decoupling zone near the border between Sikkim and western Bhutan is recognized, and coincides spatially with the rupture terminates of the 1934 Mw8.2 and the 1714 M7.5~8.5 earthquakes, indicating that the large megathrust earthquakes along the Sikkim–Bhutan Himalaya are largely segmented by the spatial variation of frictional properties on the MHT. Using a new compilation of seismic records in the Sikkim–Bhutan Himalaya, we analyze the spatial correlation between fault coupling and seismic activity. The result suggests that the seismicity in the Bhutan Himalaya is broadly distributed, instead of restricted in the lower edge of the interseismic locking zone. This implies that the seismic activity in the Bhutan Himalaya is not uniquely controlled by the stress accumulation at the downdip end of the locked portion of the MHT.

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Strong seismic coupling underneath Garhwal–Kumaun region, NW Himalaya, India

Cited by 53 publications

References 51 publications

Anomalous transients in GPS measurements due to induced changes in local site conditions

Anomalous transients in GPS measurements due to induced changes in local site conditions

Segmentation of the Main Himalayan Thrust Illuminated by Bayesian Inference of Interseismic Coupling

Interseismic Coupling beneath the Sikkim–Bhutan Himalaya Constrained by GPS Measurements and Its Implication for Strain Segmentation and Seismic Activity

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