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Source Parameter of Earthquakes in Talala, Gujarat (India): An Implication towards Seismotectonic
1  Department of Applied Geophysics, Indian Institute of Technology (ISM), Dhanbad


Talala, is an excellent place for example of triggered neo-tectonic seismicity between two Dams during monsoon. An earthquake of Mmax5.1 on November 06, 2007 at 21.160N; 70.540E, with focal depth 4.5 km and complete sequence first time recoded on latest broadband sensor. This found a Dam/Monsoon induced earthquake preceded by 18 foreshocks of 2≤Mw≤4.8 within 9hr 11 minute and smaller shocks may not recorded because of sparse network coverage. After deploy of local mobile observatories aftershocks of Mw≥1.0 were recorded which continued for months and subsided to background seismicity during four months. The same kind of phenomena repeat with Mmax5.0 on October 20, 2011 at 21.060N; 70.500E, focal depth 5.5 km, implies that the potential to generate Dam/Monsoon induced seismicity took nearly 4 years again. This phenomena continue and the sequence recorded by network of 10 broadband seismographs (3 in the Talala area and 7 at epicentral distance 30 to 300 km).

Centroid Moment Tensor (CMT) solutions and spectral source parameters of mainshock and aftershocks are evaluated to understand seismotectonic of the region. The CMT depicts major Strike-slip motion along ENE-WSW with left-lateral plane at 4.5 km depth. This indicates sympathetic fault to extension of Son-Narmada fault. The source parameters of 400 shocks of Mw 1.0 to 5.1, found seismic moment 1011 to 1016.5 N-m, source radii 120-850 meter and stress drop of 0.003 to 25.43 Mpa. The b-value, p-value, fractal dimension and slip on different faults estimated

The comparison between Talala and Koyna, Dam induced source parameters try to established in comparison to seismicity from different parts of the world

Keywords: Key words: Aftershocks; Fractals; Talala-Junagadh; Earthquakes.