EGU23-2259, updated on 22 Feb 2023
https://doi.org/10.5194/egusphere-egu23-2259
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Frequency dependent attenuation and relative site response of western Tibet

Chandrani Singh1, Ashwani Kant Tiwari1,2, Eric Sandvol3, Shirish Bose1, Namrata Jaiswal1, Niptika Jana1,4, and Arun Kumar Gupta5
Chandrani Singh et al.
  • 1Indian Institute of Technology Kharagpur, Deaprtment of Geology and Geophysics, Kharagpur, India (chandrani@gg.iitkgp.ac.in)
  • 2Department of Earth and Environmental Sciences, IISER Bhopal, Bhopal, Madhya Pradesh, India
  • 3Department of Geological Sciences, University of Missouri, Columbia, USA
  • 4Department of Applied Geophysics, IIT ISM Dhanbad, India
  • 5Ministry of Earth Sciences, India

We have formulated frequency dependent Lg and Pg attenuation tomographic models to investigate the
crustal Q values and its tectonic implications beneath western Tibet. The frequency dependent
behaviour of both Lg and Pg are studied for the frequency bands of 0.2-0.6, 0.6-1.0 and 1.0-1.4 Hz at
central frequencies of 0.4, 0.8, and 1.2 Hz, respectively, implementing both Two-Station Method
(TSM) and Reverse Two-Station Method (RTSM). The amplitudes of both the waves are fundamentally
sensitive to the crustal structures and are controlled by both scattering and intrinsic attenuation. The
frequency dependent characteristics of QLg and QPg are consistent in nature for the region. Moderate to
high Q values evident in the Lhasa terrane could supplement the trace of underthrusting Indian
lithosphere beneath the region. The average Q values for both Lg and Pg increase with increasing
frequency. The frequency dependent parameter η shows quite high values, for both the waves using
TSM and RTSM, which may indicate strong heterogeneities present in the crust. Subsequently, relative
site responses at each station are studied using RTSM for the central frequencies of 0.4, 0.8, and 1.2
Hz. Weak to negative site responses are mostly dominant in western Tibet. Relative site responses are
found to vary with frequency which could be associated with the sampling depth. We found no
correlation of site responses with the elevation.

How to cite: Singh, C., Tiwari, A. K., Sandvol, E., Bose, S., Jaiswal, N., Jana, N., and Gupta, A. K.: Frequency dependent attenuation and relative site response of western Tibet, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2259, https://doi.org/10.5194/egusphere-egu23-2259, 2023.