| Abstract Submission No. | ABS-3.1-0208 |
| Title of Abstract | Seismic b-value analysis of the subducting lithosphere in Kamchatka region |
| Authors | DIGVIJAY BHATIA*, PROF. PROSANTA KUMAR KHAN |
| Organisation | department of applied geophysics ,IIT ISM DHANBAD |
| Address | room no. 45 diamond hostel , IIT ISM Dhanbad Jharkhand 846004 Dhanbad, Jharkhand, India Pincode: 846004 E-mail: 23mc0034@iitism.ac.in |
| Country | India |
| Presentation | Oral |
| Abstract | This study presents a detailed analysis of b-value at different depth-levels within the subducting lithosphere beneath the Kamchatka region, covering between 50.5°N and 55.5°N and 155.5°E and 164.5°E. A total of 5353 earthquake event data were compiled from the USGS catalog for the period July 01, 1976 to July 29, 2025. After applying a depth error filter with 10 km and less, this is reduced to 2613 event data. Only the events with magnitudes Mw ≥ 3.0 were considered to maintain its uniformity. Using the Generic Mapping Tools (GMT), the spatial distribution of earthquakes was mapped, followed by the construction of a trench-perpendicular cross-section with a 100 km swath width to visualize the depth distribution of seismicity. Five distinct clusters were identified based on depth and spatial concentration patterns. For seismic b-value calculation, the Gutenberg¿Richter frequency¿magnitude relationship was used, and the standard error of the b-value was calculated based on the model of Shi and Bolt. The b-values across clusters range from 1.19, 0.99, 1.43, 0.992, 1.17 from shallower to deeper level) with corresponding error of 0.13, 0.02, 0.09, 0.07, 0.09 and the corresponding Mc values are 4.2, 4.2, 4.4, 4.3, 4.1, respectively. High b-values in certain clusters indicate lower stress or higher heterogeneity, whereas the little lower b-values correspond to high-stress accumulation regions. The overall results highlight the complex stress distribution within the Kamchatka subduction system, showing distinct variations in the seismogenic layer¿s behavior. We will now carry out the analysis of time-varying distribution of seismic b-values along the region, which might unravel the causes of triggering the 2025 Mw 8.8 great Kamchatka earthquake. |
| Keywords | Seismic b-value, Gutenberg-Richter frequency-magnitude relation, Seismic Hazard, Kamchatka subduction margin, Stress. |