The October 20, 2011 Mw 5.1 Talala earthquake in the stable continental region of India

The role of crystallized magma and crustal fluids in intraplate seismic activity in Talala region (Saurashtra), Western India: An insight from local earthquake tomography

“…The observed lower b-value (0.67, Rastogi et al, 2013) of the seismic swarm-like earthquake activity in this intraplate setting also indicates the possibility of increase in the pore pressure, possibly due to crustal fluids. However, as the smaller earthquakes at shallower crustal depths (b4 km) are in the zone of lower Vp and lower Vp/Vs (Fig.…”

“…13), possibly representing the zone containing water-filled cracks with several percent porosities (Lin and Shearer, 2009). Therefore, the swarm-like earthquake activities at shallower depths and as related with heavy rain/reservoir (Hainzl et al, 2015;Rastogi et al, 2013;Singh and Mishra, 2015) cannot be completely ruled out for this particular region.…”

“…They also found more fractures and high surface heat flux beneath the 2007 mainshock hypocenter, and the static Coulomb stress changes due to the co-seismic slip of the main shock and enhanced off fault aftershock occurrence. Rastogi et al (2013) reported that the 2011 Talala earthquake and aftershocks defined a shallow ENE 40-km-long trend; and the increased seismicity in this region was caused by stress perturbation due to the 2001 Bhuj earthquake. Rastogi et al (2013) also reported a low b-value (0.67) associated with the 2011 Talala sequence and suggested for increased heterogeneity and low stress within the crustal mass indicating the presence of more fractures.…”

“…Rastogi et al (2013) reported that the 2011 Talala earthquake and aftershocks defined a shallow ENE 40-km-long trend; and the increased seismicity in this region was caused by stress perturbation due to the 2001 Bhuj earthquake. Rastogi et al (2013) also reported a low b-value (0.67) associated with the 2011 Talala sequence and suggested for increased heterogeneity and low stress within the crustal mass indicating the presence of more fractures. The seismic tomography study (Singh et al, 2013), using 1135 P-and 1125 S-from 236 aftershocks of the 2011 earthquake, reported the source region of the 2011 Talala earthquake was associated with low Poisson's ratio anomalies guarded by prominent high Poisson's ratio anomalies along the active fault zone having the strike-slip motion.…”

Archaeological Evidence for Modern Coastal Uplift at Diu, Saurashtra Peninsula, India

“…The Narmada rift zone experienced shocks of a magnitude of M 5.4 at Bharuch in 1970. However, even this moderate earthquake is ranked as having been severely damaging due to poor construction practices (Rastogi et al., ). The 2010 Talala earthquake ( M w 5.1) was 100 km to the NW (Yadav et al., ).…”