| Abstract Submission No. | ABS-3.1-0062 |
| Title of Abstract | Regional Variability of Seismic Wave Attenuation in the Northwestern Himalaya: Implications for Seismic Hazard |
| Authors | Dr. Parveen Kumar*, Dr Sandeep, Dr Monika |
| Organisation | Wadia Institute of Himalayan Geology Dehradun |
| Address | Wadia Institute of Himalayan Geology DEHRADUN, UTTARAKHAND, India Pincode: 248001 E-mail: sainiparveen.saini@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | The North-west (NW) Himalaya, extending west of the Kali River and encompassing Uttarakhand, Himachal Pradesh, and the Kashmir Himalaya, is one of the most seismically active regions of the Indian subcontinent. In this study, attenuation characteristics are quantified for four sectors: (1) Kumaon, (2) Garhwal, (3) Himachal, and (4) Kashmir Himalaya. The coda normalization method is used to calculate frequency-dependent P-wave (Qp(f)) and S-wave (Qs(f)) quality factor. Attenuation parameters are obtained at 28 seismic stations. A consistent dataset and similar methodology applied across all sectors highlight the novelty of this work. The Qp(f) and Qs(f) values obtained at each station are used to determine a regional relationship for each sector of the form Q = Qof n, where Qo and ¿n¿ vary between 34¿45 and 0.90¿1.16 for P-waves, and between 58¿74 and 0.87¿1.10 for S-waves, respectively. The low Qo (<200) and high ¿n¿ (>0.8) indicate strong heterogeneity and high seismic activity, consistent with active plate-boundary regions. Regional relations established for each sector are further integrated to obtain regional relations for the NW Himalaya as Qp(f) = (38±1) f (1.03±0.02) and Qs(f) = (65±2) f (1.02±0.01). Among the sectors considered in this work, Kashmir and Kumaon exhibit lower quality factors, implying higher attenuation compared to Himachal and Garhwal, as Q is inversely proportional to the attenuation properties. High attenuation in the Kashmir Himalaya is attributed to the presence of sediments/alluvium within the Kashmir basin, while in Kumaon, it may be due to the presence of partial fluid saturation at shallow depths. In contrast, Himachal and Garhwal are characterized by relatively less attenuating crust, suggesting higher seismic hazard potential than the Kashmir and Kumaon sectors. This study delineates attenuation patterns across the NW Himalaya, providing key inputs for seismic hazard assessment, source parameter estimation, and ground-motion simulation. |
| Keywords | Himalaya, Earthquake, Attenuation, Quality factor, Seismic Hazard |