| Abstract Submission No. | ABS-3.1-0118 |
| Title of Abstract | Homogenizing Earthquake Catalogues with evaluation of seismic trends for Enhanced Seismic Hazard Evaluation in the Eastern Himalayan Syntaxis |
| Authors | Shweta Sharma*, Virendra M Tiwari, Debasis D Mohanty |
| Organisation | CSIR- North East Institute of Science and Technology |
| Address | 717 B BLW Varanasi, Uttar Pradesh, India Pincode: 221004 E-mail: 40pkshweta@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | Earthquake magnitude conversions are crucial for creating homogeneous catalogues to assess seismic hazard in the Eastern Himalaya Syntaxis (EHS), a seismically active region marked by the catastrophic 1950 Great Assam earthquake (MW 8.6). However, magnitude scales (Mb, MS, ML, MW) remain inconsistent across different reporting agencies, necessitating standardized conversion relationships among different magnitude scales. This study develops magnitude conversion equations for the Eastern Himalayan Syntaxis using seismic data from the International Seismological Centre (ISC, 1906¿2025), United States Geological Survey (USGS, 1929¿2025), and Global Centroid Moment Tensor catalogue (GCMT, 1985¿2024). Various regression techniques, such as Standard Least Squares (SLS), Inverse Least Squares (ILS), Standard Orthogonal Regression (SOR), and General Orthogonal Regression (GOR), are evaluated to determine the best conversion relationships. A notable methodological advancement is presented here with the application of singular value decomposition (SVD) for general orthogonal regression, moving away from the traditional analytical method. Key findings demonstrate robust correlation e.g., for 312 ISC-USGS events, Mb,USGS=0.82*Mb,ISC+0.87 (GOR: λ=0.8, R2= 0.80, σ=0.17) and for 48 events Mw,USGS=0.79*Ms,ISC+1.359 (GOR: λ=0.9, R2= 0.91, σ=0.16). Despite challenges from data limitations and regional tectonic variability, these equations provide a vital tool for seismic studies. When this study emphasizes on homogenization of the seismic events, we also concentrate to identify the seismic potential zones for hazard estimation by measuring the Gutenberg-Richter relationship throughout the EHS. Our preliminary b-value analyses reveal spatial variations throughout the EHS, suggesting western EHS more potential for hazard scenario compared to the eastern part. This study continues to refine magnitude conversions and b-value estimates, significantly enhancing the precision of seismic hazard assessments in the Eastern Himalayan Syntaxis. |
| Keywords | Eastern Himalayan Syntaxis, General Orthogonal Regression, Gutenberg-Richter Relationship, Seismicity, Magnitude Homogenization |