Seismic Source Characteristics and Scaling Relations in Mainland Gujarat's Intraplate Zone with Special Emphasis on Stress Drop
摘要
Estimating earthquake source parameters is important for understanding seismic characteristics and potential hazards in intraplate regions, where seismic activity often deviates from the pattern observed in interplate regions. This study focuses on Mainland Gujarat, India, which hosts a large and densely distributed population. The region has previously experienced earthquakes of up to M ~ 6.0 and remains vulnerable to similar events. We used spectral analysis techniques to quantify the key source parameters viz. stress drop, corner frequency, source radius, and seismic moment for earthquakes in this region. We have analyzed 122 local earthquakes in the Mainland Gujarat region that occurred between 2007 and 2022, with magnitudes ranging from 2.5 to 4.4. We applied a method based on the source term of the displacement spectra from observed S-wave spectra. The estimated stress drop values range from 0.08 to 28.32 MPa, with a median value of 7.18 ± 0.24 MPa, which remains nearly constant with the moment, indicating self-similarity in local earthquake behaviors. The corner frequency varies between 2.27 to 13.2 Hz, and the source radius ranges from 68.7 to 897.2 m. The seismic moment spans from 6.31 × 1012 to 5.02 × 1015 N-m. We found the scaling relationship between corner frequency and seismic moment to be M0fc3 = 2.13 × 1016 Nm/s3. This study contributes to a deeper understanding of earthquake mechanics in Mainland Gujarat and provides valuable insights into proper seismic hazards in the Gujarat region.