Shear‐Wave Velocity Reveals Heterogeneous Geometry of the Main Himalayan Thrust System and Deep Structure Beneath the Nepal Himalayas

Zhao, Lingfeng; Li, Lun; Liao, Jie; Dong, Shanliang; Liang, Y.; Gao, Rui

doi:10.1029/2021gc010263

Cited by 3 publications

(1 citation statement)

References 76 publications

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“…Seismic velocity models for all the seismic stations are shown in Figures S3 and S4 in Supporting Information S1. A comparison plot between 1D‐seismic velocity models of Bhutan (Singer, Obermann, et al., 2017), Nepal (L. Zhao et al., 2022) and Sikkim show velocity variations across different segments in Himalaya (Figure S5 in Supporting Information S1).…”

Section: Joint Inversion Of Rfs With Surface Wavesmentioning

confidence: 99%

Evidence for an Imbricated Lower Crust and Its Role in Accommodating Crustal Shortening in Sikkim Himalaya

Singh,

Kumar,

Singh

et al. 2024

Tectonics

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Geometrical heterogeneity of the subducting Indian continental crust along the Himalaya‐Tibet collision zone remains enigmatic. Mass budget estimates describing shortening across the orogen are partly derived from observations made from seismic imaging of the deep earth. Here, using data from 38 broadband seismic stations covering Sikkim Himalaya, we produce high resolution seismic images in order to fill crucial gaps in our understanding of the evolution of Himalayan collision zone. We used 12,288 high quality receiver functions computed using waveforms of earthquakes having magnitude >5.5 in the distance range of 30°–100°. Our results reveal a highly imbricated and heterogeneous crust beneath Sikkim Himalaya. The Main Himalayan Thrust (MHT) responsible for large scale earthquakes in the Himalayan collision zone is not so distinct in the migrated images, but intermittent. A dominant cluster of earthquakes at shallower depths is associated with the MHT, marked by negative amplitude arrivals. The Moho is found to be gently dipping, reaching depths of ∼60 km beneath the Higher Himalaya compared to ∼40 km in the Himalayan foredeep. Interestingly, the Moho in this part of Himalaya has offsets and overlapping segments, indicating crustal imbrication in response to active shortening. Clusters of lower crustal earthquakes coincide with the junction of offsets in the Moho.

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Section: Joint Inversion Of Rfs With Surface Wavesmentioning

confidence: 99%

Evidence for an Imbricated Lower Crust and Its Role in Accommodating Crustal Shortening in Sikkim Himalaya

Singh,

Kumar,

Singh

et al. 2024

Tectonics

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Seismic structure of the 2015 Mw7.8 Gorkha earthquake revealed by ambient seismic noise and teleseismic surface wave tomography

Lü,

Lei,

Kong

et al. 2024

Sci Rep

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The destructive 2015 Mw7.8 Gorkha earthquake occurred in the Main Himalayan Thrust due to the collision of the Indian and Asian plates, which provides a unique opportunity to understand the deep dynamic processes and seismogenic mechanisms of strong earthquakes. We construct a regional-scale shear-wave velocity model of the crust and uppermost mantle using ambient seismic noise and teleseismic surface wave at periods of 5–100 s around the Gorkha earthquake region. The new shear-wave velocity model exhibits prominently lateral heterogeneities in the Gorkha earthquake areas. We observe a high-velocity (high-V) zone around the Gorkha main shock in the Main Himalayan Thrust, indicating the existence of a high-strength asperity that sustains the stress accumulating. The aftershocks are primarily located in the low-velocity (low-V) anomalies and enclosed by two high-V anomalies, which appear to act as structural barriers that influence the spread of the aftershocks. Prominent low-Vanomalies from the lower crust to the mantle lithosphere are observed along the north–south trending rifts, suggesting the hot materials upwelling due to the tearing of the northward subducting Indian lithosphere. These observations may indicate that seismic velocity heterogeneity could play an essential role in earthquake initiation and the rupture process.

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Genetic Variation in Gaultheria nummularioides (Ericaceae: Gaultherieae) from the Sky Islands of the Himalaya-Hengduan Mountains

et al. 2022

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Species diversity is high in the Himalaya-Hengduan Mountains, particularly at the edges characterized by deep ravines and “sky islands”. Studies focused on sky-island species are sparse and the patterns observed in response to both geographic and climatic factors are inconsistent. Here phylogeographic and phylogenetic analyses of Gaultheria nummularioides, a species originating in the late Pliocene with its main distribution in the Himalaya-Hengduan Mountains, were conducted to reveal the pattern of genetic dynamics in response to physical geography, glacial fluctuations, and monsoons. We found that in this species genetic variation is higher among populations than within populations, with a significant phylogeographic boundary between the central Himalaya and the eastern Himalaya and the Hengduan Mountains. We also found a high incidence of private alleles, possibly associated with strong habitat isolation. The phylogeographic pattern recovered is consistent with populations in glacial refugia that have experienced expansion after glaciation. The divergence times of most haplotypes coincide with the time of the weakening of the Asian monsoon in these regions. Models of geographic range size showed a significant decrease from the Last Interglacial through the Last Glacial Maximum to the Current, and a predicted increase from the Current to the year 2070. Our study provides insights for understanding speciation among sky islands in this region.

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Shear‐Wave Velocity Reveals Heterogeneous Geometry of the Main Himalayan Thrust System and Deep Structure Beneath the Nepal Himalayas

Abstract: The convergence of the Indian and Asian plates with a rate of 20 ± 3 mm/year has formed the longest and highest mountain belt on Earth, the Himalayas (

Cited by 3 publications

References 76 publications

Evidence for an Imbricated Lower Crust and Its Role in Accommodating Crustal Shortening in Sikkim Himalaya

Evidence for an Imbricated Lower Crust and Its Role in Accommodating Crustal Shortening in Sikkim Himalaya

Seismic structure of the 2015 Mw7.8 Gorkha earthquake revealed by ambient seismic noise and teleseismic surface wave tomography

Genetic Variation in Gaultheria nummularioides (Ericaceae: Gaultherieae) from the Sky Islands of the Himalaya-Hengduan Mountains

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