Magnetotelluric evidence for trapped fluids beneath the seismogenic zone of the Mw6.0 Anjar earthquake, Kachchh intraplate region, Northwest India

Nagar, Mehul; Pavankumar, G.; Mahesh, P.; Rakesh, N.; Chouhan, Avinash Kumar; Danda, Nagarjuna; Chopra, Sumer; Kumar, M. Ravi

doi:10.1016/j.tecto.2021.228969

Cited by 8 publications

(2 citation statements)

References 55 publications

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“…In seismically active regions, low-velocity zones associated with the presence of partial melt, residual magma, heat escaping from the mantle, or frictional heating at fault zones exposed to shear between contact blocks act as waveguides channeling seismic waves during earthquakes (e.g. Zhao et al 2000;Qin et al, 2018;Nagar et al, 2021). However, low velocity layers are also widespread in stable cold crust regions, where they cannot be explained by increased heat and the presence of melt.…”

Section: Discussionmentioning

confidence: 99%

Geoelectric studies in earthquake hazard assessment – the case of the Kozlodui nuclear power plant, Bulgaria

Kováčiková

Boyadzhiev

Logvinov

2023

Preprint

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The study presents the results of geoelectric research for seismic risk assessment on the example of the Kozlodui nuclear power plant in Bulgaria. The image of the geoelectric structure in the study area was obtained using one-dimensional inverse electrical resistivity modeling of the full five-component magnetotelluric data and quasi-three-dimensional inverse conductivity modeling of the geomagnetic responses recorded during the summer 2021 field campaign. According to the presented results, the geoelectrically anomalous structure is divided into two levels. The near-surface anomalous structure in the immediate reach of human geotechnical activity corresponds to the electrically conductive sedimentary fill. The mid-crustal layer is coincident with the low seismic velocity zone at the brittle and ductile crust interface, revealed in previous studies. The presented results imply that the geological environment is not affected by large faults capable of transmitting seismic energy from tectonically active areas, however, in further studies, attention should be paid to the strike-slip fault systems adjacent to the study area.

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Section: Discussionmentioning

confidence: 99%

Geoelectric studies in earthquake hazard assessment – the case of the Kozlodui nuclear power plant, Bulgaria

Kováčiková

Boyadzhiev

Logvinov

2023

Preprint

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“…Since historic past, the region is experiencing moderate to large magnitude earthquakes and is considered as one of the most active intraplate regions of the world. Magnetotelluric studies carried out in various segments of the region yield well resolved electrical images of the deep crust, enabling delineation of the broad geometry of various active faults (Nagar et al, 2021). The MT models in conjunction with 3-D relocated hypocenters provide better constraints on the geometry of the seismogenic segments of the faults at depth.…”

Section: Seismogenesis Of Intraplate Kachchh Rift In Western India By...mentioning

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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