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    • Keywords


      Site characterization; microtremor; H/V spectral ratio; ampliBcation; shear wave velocity; Gorakhpur.

    • Abstract


      The microtremor measurements are carried out in and around the Gorakhpur city (Uttar Pradesh), India, overlain by alluvium at about 150 sites to understand the local site conditions. Horizontal-to-vertical spectral ratio (HVSR) conBrms that the majority of sites have a predominant frequency of ${\sim}$0.45 Hz, which may suggest the prevalence of thick soft sediments in the area. Conspicuously, a number of multiple peaks in HVSR curves at few sites may reflect the presence of different interfaces with significant impedance contrasts. Maximum amplification is observed of 4.0–5.3 to the NW–SE of the city, whilst few sites in the city are found to be associated with different values of peak amplification factor that varied between 2.0 and 4.0. It is also observed that the ground vulnerability index ($K_g$) in Gorakhpur city has values higher than 10.0 at most of the sites. Assimilation of 1-D velocity model for the city clearly shows that low shear wave velocity (${\sim}$300 m/s) down to the depth of ${\sim}$35 m, suggesting thick piles of sediments that may correspond to Cuvial river system in the area, whilst the peak frequency of about 0.45 Hz may correspond to the Quaternary–Tertiary sediment boundary that may exist at deeper layers (${\sim}$1000 m). The inference of this study may be used as inputs for earthquake risk management by reducing the severity of earthquake shaking through design of earthquake risk resilient structures.

    • Author Affiliations



      1. Department of Geophysics, Institute of Science, Banaras Hindu University, Varanasi 221 005, India.
      2. National Centre for Seismology, Ministry of Earth Sciences, Lodhi Road, New Delhi 110 003, India.
      3. Seismology division, Ministry of Earth Sciences, Lodhi Road, New Delhi 110 003, India.
    • Dates

  • Journal of Earth System Science | News

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