A magnetotelluric (MT) study across the Koyna seismic zone, western India: evidence for block structure

Sarma, S. V. S.; Prasanta, B.; Patro, K.; Harinarayana, T.; Veeraswamy, K.; Sastry, R.S.; Sarma, Mondip

doi:10.1016/j.pepi.2003.12.005

Cited by 57 publications

(40 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the revised seismotectonic framework (Fig. 2), we use additional information based on the analysis of over 600 digitally recorded earthquakes from April 1996to December 1997(SRINAGESH and SARMA 2005SARMA and SRI-NAGESH 2007) and magnetotelluric surveys in the Koyna area (SARMA et al 2004;HARINARAYANA et al 2007). …”

Section: Seismotectonic Framework In the Kwrmentioning

confidence: 99%

Hydromechanics of the Koyna–Warna Region, India

Durá‐Gómez

Talwani

2009

Pure Appl. Geophys.

View full text Add to dashboard Cite

Continuous reservoir-induced seismicity has been observed in the Koyna-Warna region in western India following the beginning of impoundment of Koyna and Warna Reservoirs in 1961 and 1985, respectively. This seismicity includes 19 events with M C 5.0 which occurred in 7 episodes (I-VII) between 1967 and 2005 at non-repeating hypocentral locations. In this study, we examined the first six episodes. The seismicity occurs by diffusion of pore pressures from the reservoirs to hypocentral locations along a saturated, critically stressed network of NE trending faults and NW trending fractures. We used the daily lake levels in the two reservoirs, from impoundment to 2000, to calculate the time history of the diffused pore pressures and their daily rate of change at the hypocentral locations. The results of our analysis indicate that Episodes I and IV are primarily associated with the initial filling of the two reservoirs. The diffused pore pressures are generated by the large (20-45 m) annual fluctuations of lake levels. We interpret that critical excess pore pressures [*300 kPa and [*600 kPa were needed to induce Episodes I-III and Episodes IV-VI, respectively, suggesting the presence of stronger faults in the region. The exceedance of the previous water level maxima (stress memory) was found to be the most important, although not determining factor in inducing the episodes. The annual rise of 40 m or more, rapid filling rates and elevated dp/dt values over a filling cycle, contributed to the rapid increase in pore pressure.

show abstract

Section: Seismotectonic Framework In the Kwrmentioning

confidence: 99%

Hydromechanics of the Koyna–Warna Region, India

Durá‐Gómez

Talwani

2009

Pure Appl. Geophys.

View full text Add to dashboard Cite

show abstract

“…The characters A, B, C and D in figure 6 indicate the major electrical features of the model. The significance of each feature has been studied by carrying out a modeling experiment with and without the feature (Sarma et al 2004;Patro et al 2005aPatro et al , 2005b. The electrical characteristics, the importance and possible geological inferences of each feature are given below.…”

Section: D Inversion Of Mt Datamentioning

confidence: 99%

Magnetotelluric investigations for imaging electrical structure of Garhwal Himalayan corridor, Uttarakhand, India

et al. 2008

View full text Add to dashboard Cite

“…Shivaji Sagar Lake created by Koyna Dam was completed during 1962. About 46 km long, the Koyna reservoir trending N-S direction and parallel to the Western Ghat hill range is believed to be a fault zone (Sarma et al 2004). Full reservoir level is 657.91 m amsl with a maximum water column at the dam site of 78.79 m and total water spread area of 115.35 km 2 (net storage 2652.45 million cubic meters (mcm)).…”

mentioning

confidence: 99%

Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

Reddy

Nagabhushanam

2015

J Seismol

View full text Add to dashboard Cite

Triggered seismicity is an accepted hypothesis in the present days. However, detailed hydrogeological investigations are lacking in the well-known reservoirtriggered seismic (RTS) zones. Here, we made an attempt to understand the direct linkage between the well-known Koyna-Warna reservoirs believed to be under the RTS zone (situated in the Deccan volcanic province (DVP), India) and the surrounding groundwater system up to 250 m deep from the ground surface. Seismic activity in the region started soon after the impoundment of water in the Koyna reservoir and being continued over the last four and a half decades. Though researchers have carried out numerous studies on the Koyna seismicity, no hydrogeological investigations were attempted. Hence, hydrogeological, hydrochemical, and isotopic investigations were carried out for 7 years on groundwaters from 15 deep bore wells (up to 250 m) and two surface reservoir waters to elucidate the direct hydraulic connectivity between them. No appreciable seasonal change was observed in piezometric heads of the artesian wells, but the semi-artesian wells did show fluctuation of~2 to 12 m during different years, which did not have any relation with the reservoir water levels. No considerable seasonal change in hydrochemistry was observed in individual wells due to the confined nature of the aquifers. The hydrochemical and δ 18 O data of the studied deep groundwaters and reservoir waters, being different from each other, rule out the possibility of direct hydraulic connectivity between them and surrounding groundwater (up to 250 m), even though favorable topographic conditions exist for linkage. The radiocarbon ages, being incomparable between different well waters, support the inference drawn from hydrochemistry and stable isotope data.

show abstract

A magnetotelluric (MT) study across the Koyna seismic zone, western India: evidence for block structure

Cited by 57 publications

References 24 publications

Hydromechanics of the Koyna–Warna Region, India

Hydromechanics of the Koyna–Warna Region, India

Magnetotelluric investigations for imaging electrical structure of Garhwal Himalayan corridor, Uttarakhand, India

Search for hydraulic connectivity between surface reservoirs and surrounding aquifers in the reservoir-triggered seismic environment (Koyna region, India) using hydrochemical and isotopic signatures

Contact Info

Product

Resources

About