Stress level monitoring using SWS measurements of local earthquakes of Garhwal Himalaya. (2021)

• Record Type: Journal Article
• Authors: Singh, Rakesh; Paul, Ajay; Rohan, ; Goyal, Sanaa
• Is Part Of: Materials today. Volume 46:Part 20(2021)
• Page Start: 10582
• Page End: 10587
• Publication Date: 2021
• Subjects: Central Seismic Gap (CSG) -- Chamoli region -- Delay time -- Seismic anisotropy -- Shear wave splitting (SWS); Materials science -- Congresses -- Periodicals; 620.1
• DOI: 10.1016/j.matpr.2021.01.320
• Languages: English
• ISSNs: 2214-7853

Abstract

Abstract: Chamoli district of Garhwal Himalaya is one of the highly seismically active region and probable zone for impending great earthquake in the CSG. In the present study, to understand the upper crustal anisotropy of Chamoli region, shear wave splitting (SWS) analysis is performed for local seismic events. For events > 2 M reported at Ghuttu station during the period Nov 2014 to JULY 2015, SWS parameters are measured. A considerable temporal difference in delay time was observed during the SWS study with respect to the 4.9Mw magnitude earthquake that occurred in the Chamoli region on 1st April 2015 at 21:23 hrs (UTC). A rise in delay time prior to the earthquake which decreases steadily over time is observed at GTU station. This decrease in delay time can be related to the region's stress relief. The calculated average delay time (δt) is 3.83 ms/km and a maximum value of 5.37 ms/km for the earthquake of magnitude 4.9Mw. Sfast polarization direction range from N120° to N170° has been observed for the majority of the earthquakes. An average NW-SE orientation of the shallow subsurface micro-cracks along the ray path beneath the Chamoli region has also observed. Present study is a step towards earthquake precursory research in Garhwal-Kumaun region for monitoring of the state of accumulated stress. This study clearly demonstrate that SWS measurements for local earthquakes can be utilized for continuous monitoring of temporal variation in time delay (δt) and probably used for stress forecast for an impending earthquake.