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Title: Source Parameters and High Frequency Characteristics of Local Events (0.5 ≤ M L ≤ 2.9) Around Bilaspur Region of the Himachal Himalaya
Authors: Vandana
Kumar A.
Gupta, Subhash Chander
Mishra O.P.
Kumar A.
Published in: Pure and Applied Geophysics
Abstract: Source parameters of 41 local events (0.5 ≤ ML ≤ 2.9) occurred around Bilaspur region of the Himachal Lesser Himalaya from May 2013 to March 2014 have been estimated adopting Brune model. The estimated source parameters include seismic moments (Mo), source radii (r), and stress drops (Δσ), and found to vary from 4.9 × 1019 to 7 × 1021 dyne-cm, about 187–518 m and less than 1 bar to 51 bars, respectively. The decay of high frequency acceleration spectra at frequencies above fmax has been modelled using two functions: a high-cut filter and κ factor. Stress drops of 11 events, with M0 between 1 × 1021 and 7 × 1021 dyne-cm, vary from 11 bars to 51 bars with an average of 22 bars. From the variation of the maximum stress drop with focal depth it appears that the strength of the upper crust decreases below 20 km. A scaling law M0 = 2 × 1022 fc −3.03 between M0, and corner frequency (fc), has been developed for the region. This law almost agrees with that for the Kameng region of the Arunachal Lesser Himalaya. fc is found to be source dependent whereas fmax is source independent and seems to indicate that the size of the cohesive zone is not sensitive to the earthquake size. At four sites fmax is found to vary from 14 to 23, 11 to 19, 9 to 23 and 4 to 11 Hz, respectively. The κ is found to vary from 0.01 to 0.035 s with an average of 0.02 s. This range of variation is a large compared to the κ variation between 0.023 and 0.07 s for the Garhwal and Kumaon Himalaya. For various regions of the world, the κ varies over a broad range from 0.003 to 0.08 s, and for the Bilaspur region the κ estimates are found to be consistent with other regions of the world. © 2017, Springer International Publishing.
Citation: Pure and Applied Geophysics (2017), 174(4): 1643-1658
Issue Date: 2017
Publisher: Birkhauser Verlag AG
Keywords: Brune model
Earthquake source parameters
Himachal Lesser Himalaya
kappa (κ)
local events
ISSN: 334553
Author Scopus IDs: 57201843019
Author Affiliations: Vandana, Ministry of Earth Sciences, New Delhi, India
Kumar, A., Department of Earthquake Engineering, Indian Institute of Technology Roorkee, Roorkee, India
Gupta, S.C., Department of Earthquake Engineering, Indian Institute of Technology Roorkee, Roorkee, India
Mishra, O.P., Ministry of Earth Sciences, New Delhi, India
Kumar, A., Arni University, Kangra, Himachal Pradesh, India
Sandeep, Banaras Hindu University, Varanasi, India
Corresponding Author: Vandana; Ministry of Earth SciencesIndia; email:
Appears in Collections:Journal Publications [EQ]

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