S. Mukhopadhyay

Indian Institute of Technology Roorkee

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J. R. Kayal

Geological Survey of India

Naresh Kumar

Wadia Institute of Himalayan Geology

J. Raoof

Indian Institute of Technology Kanpur

J. Sharma

Institute of Seismological Research

Amit Kumar

National Centre for Antarctic and Ocean Research

Iván Koulakov

Institute of Petroleum Geology and Geophysics

Andrey Jakovlev

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Akash Kharita

Indian Institute of Technology Roorkee

Rabin Das

Indian Institute of Technology Roorkee

Chandrani Singh

Indian Institute of Technology Kharagpur

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Indian Institute of Technology Roorkee

Wadia Institute of Himalayan Geology

Indian Institute of Technology Kharagpur

Council of Scientific and Industrial Research

National Geophysical Research Institute

Novosibirsk State University

Institute of Petroleum Geology and Geophysics

Ministry of Earth Sciences

Geological Survey of India

V.S. Sobolev Institute of Geology and Mineralogy

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Wet Mantle Transition Zone beneath the Indian shield? Constraints from P-to-S Receiver Functions Analysis

Akash Kharita S. Mukhopadhyay

Earth and Space Science Open Archive This preprint has been submitted to and is under consideration at Physics of the Earth and Planetary Interior. ESSOAr is a venue for early communication or feedback before peer review. Data may be preliminary.Learn more about preprints preprintOpen AccessYou are viewing the latest version by default [v2]Wet Mantle Transition Zone beneath the Indian shield? Constraints from P-to-S Receiver Functions AnalysisAuthorsAkashKharitaiDSagarikaMukhopadhyayiDSee all authors Akash KharitaiDCorresponding Author• Submitting AuthorIndian Institute of Technology RoorkeeiDhttps://orcid.org/0000-0003-0612-7734view email addressThe email was not providedcopy email addressSagarika MukhopadhyayiDIndian Institute of Technology RoorkeeiDhttps://orcid.org/0000-0003-1581-1474view email addressThe email was not providedcopy email address

Preprint

10.1002/essoar.10510960.2

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Citations (1)

Lg Attenuation Characteristics across the Indian Shield

Bulletin of the Seismological Society of America (2011)

Chandrani Singh Arun Singh S. Mukhopadhyay M. Shekar R. K. Chadha

Abstract New measurements of Lg Q are obtained using a reliable two-station method to understand the attenuation characteristics across the Indian subcontinent. We use data from 514 events with magnitude≥3.5 and depth less than 40 km collected during 2006–2008 from 17 stations deployed across India. We measure 1-Hz Lg Q ( Q 0 ) values between many pairs of stations. Finally, 34 high-quality interstation paths were selected from 336 possible pairs that are (1) aligned approximately with the source and (2) separated enough to permit the use of the standard two-station method for Lg Q measurement. We found some spatial variation in Lg wave attenuation across India. Low- Q regions are present in western India. We attribute this to the recent tectonic activities in this region. The central Indian platform shows a moderate to high Q 0 value. The southernmost part of India exhibits higher values, which may indicate that the crust in this part is more stable. The obtained values correlate with the regional crustal heterogeneities and tectonic trends. As a whole, the estimated interstation Q 0 values compare well with the areas of moderate seismicity across the Earth.

Indian Shield

10.1785/0120100239

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Citations (20)

Attenuation of coda waves in the Aswan Reservoir area, Egypt

Tectonophysics (2010)

Haggag H. Mohamed S. Mukhopadhyay J. Sharma

Coda

10.1016/j.tecto.2010.05.018

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Citations (11)

Attenuation Mechanism of Seismic Wave in Chamoli Region of Garhwal-Kumaun Himalayas

72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010 (2010)

Ankit Kumar S. Mukhopadhyay Edoardo Del Pezzo

In this study the S-wave attenuation mechanism is analyzed and intrinsic and scattering attenuation effects are separated. This helps in understanding the physical mechanisms governing attenuation properties of the crust of this region. It has been observed that the Qs−1, Qd−1 and Qc−1 values at all frequencies are comparable. The estimated Le−1, B0, Qi−1, Qs−1, Qd−1 and Qc−1 values show that S-wave attenuation is primarily controlled by scattering attenuation in the source zone of the 1999 Chamoli earthquake. My results also show that for the source zone of 1999 Chamoli earthquake in the Garhwal Himalayas seismic albedo is very high, i.e. attenuation is mainly controlled by scattering attenuation. In conclusion, The extinction length Le varies between about 12 km to about 125 km in the study region. The seismic albedo (B0) values vary between 0.65 and 0.8. B0 values are very large (>0.5) showing that at all frequencies scattering attenuation is the dominating factor causing attenuation of seismic waves. This shows that the degree of heterogeneity is very high for the frequency range considered in this area.

Anelastic attenuation factor

Albedo (alchemy)

10.3997/2214-4609.201401346

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Regional variation of coda wave attenuation in Northeast India: An understanding of the physical state of the medium

Physics of The Earth and Planetary Interiors (2019)

Rabin Das S. Mukhopadhyay

Coda

Intensity

10.1016/j.pepi.2019.106404

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A shallow mantle seismic discontinuity beneath northeast India: Evidence from receiver function analyses

Journal of Asian Earth Sciences (2024)

Devajit Hazarika Neeharika Shukla Amlanjyoti Das Somak Hajra S. Mukhopadhyay

Receiver function

Discontinuity (linguistics)

10.1016/j.jseaes.2024.106375

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Spatial variations of seismic attenuation in the North West of Iranian plateau from analysis of coda waves

Tectonophysics (2017)

Mojtaba Naghavi Habib Rahimi Ali Moradi S. Mukhopadhyay

Coda

10.1016/j.tecto.2017.04.026

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Lapse-Time Dependence of Coda Q in the Source Region of the 1999 Chamoli Earthquake

Bulletin of the Seismological Society of America (2008)

S. Mukhopadhyay J. Sharma R. Massey J. R. Kayal

Abstract In the present study the attenuation of seismic-wave energy in and around the source area of the Chamoli Earthquake of 29 March 1999 is estimated using aftershock data. Most of the analyzed events are from the vicinity of the main central thrust (MCT), which is a well-defined tectonic discontinuity in the Himalayas. The method of a single backscattering model is employed to calculate frequency dependent values of coda Q ( Q c ). A total of 30 aftershock events are used for Q c estimation at central frequencies 1.5, 3, 6, 9, 12, 18, and 24 Hz through five lapse-time windows from 10 to 50 sec starting at double the travel time of the S wave. The observed Q c is strongly dependent on frequency, which indicates that the region is seismically and tectonically active with high heterogeneities. The variation of Q c has also been estimated at different lapse times to observe its effect with depth. The variation of Q c with frequency and lapse time shows that the lithosphere becomes more homogeneous with depth. Q c -values for higher frequencies increase very fast with depth within about the top 63 km of the lithosphere and then become more or less constant beyond this depth. This indicates that turbidity at higher frequency decays very fast with depth, and the mantle may be transparent to high-frequency waves. The variation of Q c at 1.5 Hz with lapse time matches quite well with those predicted by Gusev (1995). However, the frequency parameter n in the relation Q c = Q 0 f n , where Q 0 = Q c at 1 Hz, does not follow the expected pattern given in his model. This could be due to faster depth decay of turbidity as mentioned previously.

Coda

10.1785/0120070258

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Citations (48)

Seismic Tomography Structure of the 1999 Chamoli Earthquake Source Area in the Garhwal Himalaya

Bulletin of the Seismological Society of America (2003)

S. Mukhopadhyay

Simultaneous inversion of about 5000 seismic phase data of 391 aftershocks of the 29 March 1999 Chamoli earthquake ( m b 6.3), recorded by 28 closely spaced temporary and permanent seismic stations, sheds new light on understanding the seismogenic structure of the source area. The best-located 160 aftershocks ( m d 2.0-4.0) with root mean square error less than 0.2 sec and epicentral and depth error less than 1 km are clustered at a depth range of 8-16 km, above the plane of detachment, the interface between the Himalayan sedimentary wedge and the Indian shield. The mainshock nucleated by thrust faulting at the “fault end,” where the Alakananda fault meets the plane of detachment at a depth of 15 km, and the aftershocks occurred by shear adjustment at the Alakananda fault. The 3D P - and S -wave velocity structures of the source area show an east-west-trending low-velocity zone (LVZ). The LVZ is comparable with the north-dipping or near-vertical Alakananda fault on the surface. It extends from the surface down to 15 km depth. It broadens in the north-south direction at shallower (0-10 km) depth and narrows at deeper depth (10-15 km). The P -wave tomography shows a high-velocity zone (HVZ) at the eastern margin of the LVZ. The mainshock and the aftershocks occurred at the contact of these two zones and within the HVZ. The S -wave velocity structure resembles that of the P wave, but it shows an LVZ at the mainshock source area at a depth of 15 km where the higher P -wave velocity structure (HVZ) is observed. The seismogenic source area is thus characterized by a higher V P/ V S or higher Poisson's ratio at the fault end. This anomaly may be due to fluid-filled fractured rock matrix, which might have contributed to the nucleation of the mainshock. Manuscript received 17 June 2002.

Seismic Tomography

10.1785/0120020130

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Citations (53)

Low cost seismic microzonation using microtremor data: an example from Delhi, India

Journal of Asian Earth Sciences (2004)

S. Mukhopadhyay Peter Bormann

Microtremor

Seismic microzonation

10.1016/j.jseaes.2003.11.005

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Citations (50)