Seismic Imaging of Crust Beneath the Western Tibet‐Pamir and Western Himalaya Using Ambient Noise and Earthquake Data

Kumar, Vivek; S., S.; Hawkins, Rhys; Bodin, Thomas

doi:10.1029/2021jb022574

Cited by 9 publications

(11 citation statements)

References 204 publications

(544 reference statements)

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“…Previous studies have proved that the underthrusting Indian lower crust reaches varying latitudes below the southern LT, and undergoes partial eclogitization or underplating by mantle mafic materials (Kumar et al., 2022; Shi et al., 2016; Q. Xu et al., 2017). Three NE‐trending PRFs sections crossing the EHS and surrounding area have revealed that the underthrusting Indian lower crust extends beyond at least the Jiali fault (C. Y. Wang et al., 2019).…”

Section: Discussionmentioning

confidence: 99%

“…Additionally, thermodynamic numerical predictions demonstrate that the 3‐D geometry of a curved subduction slab is important for producing the observed deformation patterns and exhumation at syntaxes (Bendick & Ehlers, 2014). Tomographic images reveal that the subducting Indian plate reaches the Bangong‐Nujiang suture at depths of 100–150 km (Dubey et al., 2022), but the underthrusting of the Indian lower crust, which is widely reported in the Himalayan orogenic belt (Kumar et al., 2022), is rarely observed in the core of the EHS.…”

Section: Introductionmentioning

confidence: 99%

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Underthrusting and Pure Shear Mechanisms Dominate the Crustal Deformation Beneath the Core of the Eastern Himalayan Syntaxis as Inferred From High‐Resolution Receiver Function Imaging

Ding

Pei

et al. 2022

Geophysical Research Letters

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How the crust in the core of the Eastern Himalayan Syntaxis (EHS) deforms responding to the India‐Asia collision remains ambiguous. Here we present the first high‐resolution receiver functions image of crustal structure along a new NW‐SE trending dense nodal array crossing the core of the EHS. Two sets of low velocity zones (LVZs) are clearly observed: one with a flat style beneath the western Lhasa terrane and Higher Himalaya at 18–20 km depth and the other with two west‐dipping shapes below the western Yarlung‐Zangbo suture within 10–30 km depth. These LVZs caused by partial melting and aqueous fluids are disconnected, impeding the formation of crustal flow. A discontinuous east‐dipping intra‐crustal discontinuity and a sharp Moho offset of 7 km under the Aniqiao‐Motuo shear zone are identified, suggesting that the underthrusting of the Indian lower crust and pure shear mechanisms jointly dominate crustal deformation in the core of the EHS.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Underthrusting and Pure Shear Mechanisms Dominate the Crustal Deformation Beneath the Core of the Eastern Himalayan Syntaxis as Inferred From High‐Resolution Receiver Function Imaging

Ding

Pei

et al. 2022

Geophysical Research Letters

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“…The single-day data is then subjected to time-domain normalization (running absolute mean) and spectral whitening, followed by computing the geometrically normalized cross-correlations (CCGN; Schimmel et al 2011) for all possible raypaths. The daily cross-correlations are further stacked using the time-frequency phaseweighted stack (tf-pws) approach (Schimmel et al 2011) to enhance the signal-to-noise ratio (e.g., Acevedo et al 2019;Kumar et al 2022). We combine the causal and anti-causal parts of the daily cross-correlation and produce symmetric stacked correlations.…”

Section: Group Velocity Dispersion Measurements and Noise Source Char...mentioning

confidence: 99%

3D geometry of the Lonar impact crater, India, imaged from cultural seismic noise

Kumar¹,

Rai²

2023

Preprint

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The Lonar impact crater in the Deccan Volcanic Province of India is an excellent analogue for impact-induced structures on the Moon and other terrestrial planets. We present a detailed architecture of the crater using a high-resolution 3-D seismic velocity image to a depth of 1.5 km through the inversion of ambient noise data recorded over 20 broadband seismographs operating around the crater. The ambient noise waveform is dominated by cultural noise in the 1-10 Hz band. The shear wave velocity (Vs) model is created from Rayleigh wave group velocity data with a horizontal resolution of 0.5-1 km in the period range of 0.1-1.2 s. A key feature of the model is a velocity reduction of 10-15 % below the crater compared to outside the ejecta zone. The low-velocity zone below the crater is nearly circular and extends to a depth of ~500 m. This estimated crater’s depth is consistent with global depth-diameter scaling relations for simple craters. The basement, with a Vs of more than 2.5 km/s, lies beneath the Deccan basalt, which has a Vs of ~2.4 km/s. These results are consistent with laboratory-measured data from the Lonar crater and borehole data in the western Deccan trap. This study opens a new window for exploring impact craters and sub-basalt structures using high-frequency ambient noise tomography.

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“…Broader low-velocity zone at mid-crustal depth beneath the southern parts of Tibet and Karakoram fault is due to the presence of partial melting and/or aqueous fluids. Kumar V., et al (2022) used ambient noise cross-correlations from 530 seismological stations along with surface wave observations from 1,261 earthquakes to image the crust beneath the western Himalaya-Asia convergence zone encompassing western Himalaya-western Tibet-Ladakh-Karakoram-Pamir-Hindu Kush. The seismological data from the PASSCAL experiments, the Global Seismograph Network, experiments in Kyrgyzstan, Kazakhstan, Tajikistan, China, Nepal and western Tibet, French deployments in western Kunlun and Kazakhstan and Indian deployments in the western Himalaya were used in this study that resulted in 22,726 inter-station Rayleigh wave dispersion measurements in the period band of 5 to 60 s at a horizontal resolution of less than 0.5 • ×0.5 • .…”

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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Seismic Imaging of Crust Beneath the Western Tibet‐Pamir and Western Himalaya Using Ambient Noise and Earthquake Data

Abstract: The Himalaya-Tibet-Pamir mountain belts (Figure 1) have an evolutionary history beginning about 60 Myr ago with the closure of the Tethys Ocean followed by the collision of the Eurasian and Indian landmass (

Cited by 9 publications

References 204 publications

Underthrusting and Pure Shear Mechanisms Dominate the Crustal Deformation Beneath the Core of the Eastern Himalayan Syntaxis as Inferred From High‐Resolution Receiver Function Imaging

Underthrusting and Pure Shear Mechanisms Dominate the Crustal Deformation Beneath the Core of the Eastern Himalayan Syntaxis as Inferred From High‐Resolution Receiver Function Imaging

3D geometry of the Lonar impact crater, India, imaged from cultural seismic noise

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

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