Evidence for a fluid flow triggered spatio-temporal migration of seismicity in the 2001 M$^w$ 7.7 Bhuj earthquake region, Gujarat, India, during 2001–2013

Journal of Earth system science

Prantik Mandal1¹  Koushik Biswas1¹  Manish Kumar1¹ 

[1]CSIR – National Geophysical Research Institute, Uppal Road, Hyderabad 500 007, AP, India.$$

关键词: Fluid flow;    migration of seismicity;    relocations;    rift zone;    pore-pressure relaxation;    seismic diffusivity;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

We studied the variations in spatial and temporal clustering of earthquake activity (during 2001–2013) in the Kachchh seismic zone, Gujarat, India, by precisely relocating 3478 events using a joint hypocentral determination (JHD) relocation technique, and high-quality arrival times of 21032 P- and 20870 S-waves.Temporal disposition of estimated station corrections of P- and S-waves suggests that the fluid flow in the causative fault zone of the 2001 Bhuj mainshock increased during 2001–2010, while it reduced during 2011–2013, due to the healing process associated with the perturbed Kachchh fault zone. We also estimated the isotropic seismic diffusivities from epicentral growth patterns, which are found to bemuch lower than those observed for reservoir-induced seismicity sites in the world. Finally, we analysed the spatial and temporal evolution of this earthquake sequence by solving the diffusion equation of pore-pressure relaxation caused by co- and post-seismic stress changes associated with earthquakes. The value of the isotropic diffusivity is estimated to be 100 m2/s for the Kachchh rift zone. This gives a higher permeability (after a lapse time of 14 years from the occurrence of the 2001 Bhuj mainshock) in comparison to those observed for other intraplate regions in the world. Our results suggest that the observed spatio-temporal migration of seismicity is consistent with the shallow (meteoric water circulationat 0–10 km depths) and deeper (metamorphic fluid and volatile CO2 circulation at 10–40 km depths) fluid flows in the permeable and fractured causative fault zone of the 2001 Bhuj earthquake.

【 授权许可】

Unknown