Estimation of S-wave site response in and around Delhi region from weak motion data

Journal of Earth system science

S K Nath1²  R Prakash2¹  S K Srivastav2¹  H V Gupta2¹  R S Dattatrayam2¹  S N Bhattacharya2¹  P Sengupta1² 

[1] India Meteorological Department, New Delhi 110 003, India$$;Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721 302, India$$

关键词: Site response;    classical and normalised standard spectral ratio;    receiver function;    site effects by generalised inversion;    local site condition;    Delhi telemetry network.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Site response in and around Delhi is studied using digital seismograms recorded by a thirteen-station VSAT-based 24-bit digital Delhi telemetry network of the India Meteorological Department. Nine local (𝑀l ≥ 2.3) and nine regional (𝑀l ≥ 3.9) earthquakes are selected for the estimation of site amplification factor using the classical standard spectral ratio for regional events (Ridge Delhi Observatory being the reference station), normalized standard spectral ratio for local events, horizontal-to-vertical spectral ratio or receiver function and the generalized inversion techniques in the frequency range of 0.5 to 7.5 Hz. Site response curves at all the thirteen stations exhibit station to station variation of the site amplification factor reflecting the changes in geologic/geotectonic/soil conditions. A comparison of the site response values obtained by the generalized inversion with those computed using receiver function technique shows a large scatter even though the pattern of the curves remain more or less similar. However, the site effects computed by generalized inversion and standard spectral ratio exhibit a good 1:1 correspondence. The peaks yielded by all the methods have been observed to occur at the same frequencies. It is evident that the softer fluvial deposits of the newer alluvium of the east Yamuna sector show steeper site amplification gradient at lower frequencies, while the greater Delhi experiences moderate site amplification. The variation of site response corroborates the abrupt changes in intensity from one location to another due to local site condition.

【 授权许可】

Unknown