Imaging the Moho and Main Himalayan Thrust beneath the Kumaon Himalaya: constraints from receiver function analysis

Hazarika, Devajit; Hajra, Somak; Kundu, Abhishek; Bankhwal, Meena; Kumar, Naresh; Pant, Charu C.

doi:10.1093/gji/ggaa478

Cited by 25 publications

(11 citation statements)

References 76 publications

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“…However, larger linear crustal accommodation rate (2.64 ± 1.66 mm/a) is taking place at the western edge of the Almora Klippe between Baijro and Chamoli. Extended level of seismicity from MCT towards Baijro and greater deformation in this region suggest that the local thrusts (NAT and SAT) are asymptotically connected to the gently dipping MHT as compared to the eastern part of the Almora Klippe 30 , 50 (Fig. 6 ).…”

Section: Resultsmentioning

confidence: 96%

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Crustal velocity and interseismic strain-rate on possible zones for large earthquakes in the Garhwal–Kumaun Himalaya

Pappachen

Sathiyaseelan

Gautam

et al. 2021

Sci Rep

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The possibility of a major earthquake like 2015 Gorkha–Nepal or even greater is anticipated in the Garhwal–Kumaun region in the Central Seismic Gap of the NW Himalaya. The interseismic strain-rate from GPS derived crustal velocities show multifaceted strain-rate pattern in the region and are classified into four different strain-rate zones. Besides compressional, we identified two NE–SW orienting low strain rate (~ 20 nstrain/a) zones; namely, the Ramganga-Baijro and the Nainital-Almora, where large earthquakes can occur. These zones have surface locking widths of ~ 72 and ~ 75 km respectively from the Frontal to the Outer Lesser Himalaya, where no significant surface rupture and associated large earthquakes were observed for the last 100 years. However, strain reducing extensional deformation zone that appears sandwiched between the low strain-rate zones pose uncertainties on the occurences of large earthquakes in the locked zone. Nevertheless, such zone acts as a conduit to transfer strain from the compressional zone (> 100 nstrain/a) to the deforming frontal active fault systems. We also observed a curvilinear surface strain-rate pattern in the Chamoli cluster and explained how asymmetric crustal accommodation processes at the northwest and the southeast edges of the Almora Klippe, cause clockwise rotational couple on the upper crust moving over the MHT.

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Section: Resultsmentioning

confidence: 96%

“…The overlyed geological map is taken from Thakur et al, 2018 27 . Blue bold line indicate the MHT across northwestern part of the Almora Klippe 30 and the Red bold line indicates the geometry of the MHT in the southeastern part of the Almora Klippe 50 . Moho geometry of both profiles are indicated in blue and red dash lines.…”

Section: Resultsmentioning

confidence: 99%

Crustal velocity and interseismic strain-rate on possible zones for large earthquakes in the Garhwal–Kumaun Himalaya

Pappachen

Sathiyaseelan

Gautam

et al. 2021

Sci Rep

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“…Long transverse structures in the eastern Himalaya foredeep region, like those of the East Patna Fault, Tista Fault, Dhubri Fault, Kopili Fault, Bomdila Fault, and in the EHS the Mishmi/Lohit/Walong fault systems play a major role in generating earthquakes in this region (Figure 3). Several investigations by semi‐permanent and temporary seismic networks in the eastern Himalayas indicate bimodal seismicity and deeper earthquakes down to 40–80 km, which do not fit with the envisaged MHT in the seismotectonic model (De & Kayal, 2003; Hazarika et al, 2017, 2021; Kayal, 2001, 2010; Kayal et al, 1993; Monsalve et al, 2006). We believe that the long NE and NW trending transverse structures/faults from foredeep to the High Himalayas, even beyond, which may be existed since the time predating the birth of the Himalayas, accommodate the plate convergence by conjugate shear failure on these faults (Dasgupta et al, 1987, 2013; Kayal et al, 2012; Mukhopadhyay, 1984).…”

Section: Discussionmentioning

confidence: 98%

Recent large and strong earthquakes in the eastern Himalayas: An appraisal on seismotectonic model

et al. 2022

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Since 1934, two great earthquakes (Mw ≥8.0) and some eight large/strong earthquakes (Mw 6.5–7.8) occurred in the eastern Himalayas, from eastern Nepal to the Eastern Himalayan Syntaxis (EHS) Zone. All these events are instrumentally recorded by local as well as by the global network. From west to east these events are the 2015 two large/devastating earthquakes (Mw 7.8 and 7.3, respectively) in eastern Nepal, the 1934 and 1988 Bihar–Nepal earthquakes (Mw 8.1 and 6.8, respectively), the 2011 Sikkim (Mw 6.9), the 1967 and 2009 Bhutan (Mw 6.5 and 6.3, respectively), 1964 and 1947 Arunachal–Tibet (Mw 6.5 and 7.0, respectively), and the 1950 Assam–Tibet great (Mw 8.4) earthquakes. Most recently, on 28 April 2021, an earthquake Mw 6.1 occurred in the Assam foredeep. These events are documented as shallow (0–20 km) Main Himalayan Thrust (MHT) earthquakes in the International Seismological Center and National Earthquake Information Center—USGS catalogues. With the advent of local digital seismic networks and better precision of hypocentre locations, the eastern Himalayan earthquake source zones are found to be much different; these are not typically MHT events. Precise hypocentre locations indicate bimodal seismicity at shallower (0–20 km) as well as at deeper depths (40–70 km) in the eastern Himalayas. Seismic cross‐sections and fault plane solutions of the earthquakes do not support a uniform seismotectonic model for the entire Himalayas. All the instrumentally recorded past great earthquakes in the Himalayas and the recent destructive earthquakes in the eastern Himalayas study region are critically examined in view of the known seismotectonic model, and we suggest that each large/great earthquake occurred in its own unique complex tectonic environment. The transverse structures play a major role in generating the deeper earthquakes in the eastern Himalayas and the EHS; the shallower MHT may be flattened.

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“…A ramp (∼ 20 • ) structure on the MHT is revealed beneath the CCB. The spatial and depth distribution of seismicity pattern beneath the CCB and presence of steep dipping imbricate faults inferred from focal mechanism solutions suggest a Lesser Himalayan Duplex structure in the CCB above the MHT ramp (Hazarika et al, 2021;Hajra et al, 2021). 2022) obtained 3D models of the crust and uppermost mantle beneath the NW Himalaya down to a depth of 120 km by local earthquake seismic tomography using data of India Meteorological Department (IMD) complemented by the Global International Seismological Centre (ISC) Catalogue.…”

Section: Himalayamentioning

confidence: 99%

INSA National Report on Seismological Research in India: 2019 – 2022

Manglik

2023

Preprint

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The Indian National Science Academy (INSA), the National Adhering body representing India in the International Union of Geodesy and Geophysics (IUGG), submits a National Report to the IUGG during its General Assembly, held every four years. The present chapter is a compilation for the International Association of Seismology and Physics of the Earth's Interior (IASPEI), one of the eight Associations of the IUGG, encompassing the scientific activities carried out in the country during 2019-2022, in the field of seismology. The chapter is arranged to categorize the contributions under internal structure of the Indian lithosphere and sub-lithospheric mantle, crust and upper mantle deformation, seismic attenuation, seismic hazards, triggered seismicity, environmental seismology, paleoseismology and seismological networks. In addition, the chapter includes activities related to societal projects and outreach programs. It is not an exhaustive review of the entire Indian contribution to seismology and allied fields during this period but a window to the topics covered within the framework of IASPEI.During the reporting period, researchers from several Indian R&D and Academic Institutions continued adding new results on the crustal and upper mantle structure of the Indian shield, both at regional and geological province scale. The Himalaya has been a major focus of seismological research for many Institutes who operated broadband seismological networks from Kashmir to Arunachal along the Himalayan arc. The data from these networks have facilitated in enhancing our understanding of the structure of the Main Himalayan Thrust, crustal and upper mantle structure as well as the dip of the underthrusting Indian plate, seismicity monitoring, and estimation of attenuation. Some of these networks also include accelerographs for strong ground motion studies. A few studies also focused on mapping of the mantle transition zone beneath the Indian Ocean Geoid Low. The studies on anthropogenic seismicity added near-field investigations in the Koyna -Warna region through borehole seismology. Organization of the Joint Scientific Assembly of IAGA and IASPEI during 21-27 August 2021 (JSA-2021) was a major event during this period related to the IUGG activities. Originally, the event was planned to be hosted at Hyderabad, India, but due to the COVID-19 pandemic it was organized in virtual mode. Initiatives have been taken to nucleate the field of environmental seismology in the country.

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Imaging the Moho and Main Himalayan Thrust beneath the Kumaon Himalaya: constraints from receiver function analysis

Cited by 25 publications

References 76 publications

Crustal velocity and interseismic strain-rate on possible zones for large earthquakes in the Garhwal–Kumaun Himalaya

Crustal velocity and interseismic strain-rate on possible zones for large earthquakes in the Garhwal–Kumaun Himalaya

Recent large and strong earthquakes in the eastern Himalayas: An appraisal on seismotectonic model

INSA National Report on Seismological Research in India: 2019 – 2022

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