• Seismic hazard scenario and attenuation model of the Garhwal Himalaya using near-field synthesis from weak motion seismometry

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    • Keywords


      Garhwal Himalaya; maximum credible earthquake; site amplification; spectral acceleration; attenuation relation.

    • Abstract


      In this paper, we present a seismic hazard scenario for the Garhwal region of the north-western Himalayan range, in terms of the horizontal Peak Ground Acceleration. The scenario earthquake of moment magnitude 𝑀w 8.5 has a 10% exceedance probability over the next 50 years. These estimates, the first for the region, were calculated through a stepwise process based on:

      • An estimation of the Maximum Credible Earthquake from the seismicity of the region and Global Seismic Hazard Assessment Program considerations, and
      • four seismotectonic parameters abstracted from near field weak-motion data recorded at five stations installed in Chamoli District of the Garhwal region in the aftermath of the 1999 Chamoli earthquake. The latter include:
      • The frequency dependent power law for the shear wave quality factor, 𝑄𝑆
      • the site amplification at each station using horizontal-to-vertical-spectral ratio and generalized inversion technique,
      • source parameters of various events recorded by the array and application of the resulting relations between the scalar seismic moment 𝑀0 (dyne-cm) and moment magnitude Mw and the corner frequency, 𝑓𝑐 (Hz) and moment magnitude 𝑀w to simulate spectral acceleration due to higher magnitude events corresponding to the estimated Maximum Credible Earthquake, and
      • regional and site specific local spectral attenuation relations at different geometrically central frequencies in the low, moderate and high frequency bands.
    • Author Affiliations


      Sankar Kumar Nath1 Khemraj Shukla1 Madhav Vyas2

      1. Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721 302, India.
      2. Schlumberger Limited, Houston, Texas 77077, USA.
    • Dates

  • Journal of Earth System Science | News

© 2017 Indian Academy of Sciences, Bengaluru.