Earthquakes began to occur in Koyna region （India） soon after the filling of Koyna Dam in 1962. In the present study, three datasets 1964-1993, 1993-1995, and 1996-1997 are analyzed to study the b-value and fractal ...Earthquakes began to occur in Koyna region （India） soon after the filling of Koyna Dam in 1962. In the present study, three datasets 1964-1993, 1993-1995, and 1996-1997 are analyzed to study the b-value and fractal dimension. The b-value is calculated using the Gutenberg- Richter relationship and fractal dimension Dcorr. using correlation integral method. The estimated b-value and Dcorr. of this region before 1993 are found to be in good agreement with previously reported studies. In the sub- sequent years after 1995, the b-value shows an increase. The estimated b-values of this region are found within the limits of global average. Also, the pattern of spatial clustering of earthquakes show increase in clustering and migration along the three zones called North-East Zone, South-East Zone （SEZ）, and Warna Seismic Zone. The earthquake events having depth ≤5 km are largely confined to SEZ. After 1993, the Dcorr. shows decrease, implying that earth- quake activity gets clustered. This seismic clustering could be helpful for earthquake forecasting.展开更多
The Koyna reservoir located close to the west coast of India is a classic example of reservoir triggered seismicity(RTS),where artificial water reservoir -triggered earthquakes have been occurring in a restricted area...The Koyna reservoir located close to the west coast of India is a classic example of reservoir triggered seismicity(RTS),where artificial water reservoir -triggered earthquakes have been occurring in a restricted area of 20×30 m^2 for the last 44 years.The world’s largest triggered earthquake of magnitude 6.3 occurred in Koyna on 10 December 1967,followed by several moderate to small earthquakes ever since.展开更多
Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with trigg...Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with triggered seismic events. About 410 events around a known mining area were ob-served during January 2007-October 2013. In general the quarry blasts are carried out mostly during the day time. Based on this fact a well known method of [1] is implemented, which has the capability of detecting the areas of quarry blast activity. Also, discrimination of quarry blasts from earthquakes has been achieved by studying waveforms at key seismic stations located close to the quarrying area. Further, distinction is achieved through spectral analysis in the frequency band of 3 - 15 Hz. Ratio of day-time to night-time events, waveform pattern and spectral analysis approach confirm the presence of quarry blasts aligned south-east of the Warna reservoir.展开更多
Koyna region, a seismically active region, has many time series observations such as seismicity, reservoir water levels, and many bore well water levels. One of these series is used to predict others since these param...Koyna region, a seismically active region, has many time series observations such as seismicity, reservoir water levels, and many bore well water levels. One of these series is used to predict others since these parameters are interlinked. If these series were stationary, we used correlation analysis. However, it is seen that maximum of these time series are nonstationary. In this case, co-integration method is used that is extracted from econometrics and forecast is possible. We have applied this methodology to study time series of reservoir water levels of this region and we find them to be co-integrated. Therefore, forecast of water levels for one of the reservoir is done from the other as these will never drift apart too much. The outcomes demonstrate that a joint modelling of both data sets based on underlying physics resolves to be sparingly useful for understanding predictability issues in reservoir induced seismicity.展开更多
Identification of precise hypocenter location is useful in order to improve the faults plane orientation and seismic zone analysis. In the study area, relocated hypocenter of earthquakes in Koyna-Warna region (KWR) fr...Identification of precise hypocenter location is useful in order to improve the faults plane orientation and seismic zone analysis. In the study area, relocated hypocenter of earthquakes in Koyna-Warna region (KWR) from the short period recorded data from 6th January 2010 to 28th May 2010 by using Cross-Correlation waveform results in Double Difference Hypocenter method [1]. The results show the significant improvement in hypocenter location and orientation in earthquake hypocenters, which is correlated with local faults plane orientation in study region. From the observations the earthquake hypocenters are lying in the depth between 3 to 8 km. The result which identified three faults plane orientation in NNW-SSE direction and also identified new fractures in NE-SW directions between the faults plane orientation with short duration data sets the first time in India.展开更多
文摘Earthquakes began to occur in Koyna region （India） soon after the filling of Koyna Dam in 1962. In the present study, three datasets 1964-1993, 1993-1995, and 1996-1997 are analyzed to study the b-value and fractal dimension. The b-value is calculated using the Gutenberg- Richter relationship and fractal dimension Dcorr. using correlation integral method. The estimated b-value and Dcorr. of this region before 1993 are found to be in good agreement with previously reported studies. In the sub- sequent years after 1995, the b-value shows an increase. The estimated b-values of this region are found within the limits of global average. Also, the pattern of spatial clustering of earthquakes show increase in clustering and migration along the three zones called North-East Zone, South-East Zone （SEZ）, and Warna Seismic Zone. The earthquake events having depth ≤5 km are largely confined to SEZ. After 1993, the Dcorr. shows decrease, implying that earth- quake activity gets clustered. This seismic clustering could be helpful for earthquake forecasting.
文摘The Koyna reservoir located close to the west coast of India is a classic example of reservoir triggered seismicity(RTS),where artificial water reservoir -triggered earthquakes have been occurring in a restricted area of 20×30 m^2 for the last 44 years.The world’s largest triggered earthquake of magnitude 6.3 occurred in Koyna on 10 December 1967,followed by several moderate to small earthquakes ever since.
文摘Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with triggered seismic events. About 410 events around a known mining area were ob-served during January 2007-October 2013. In general the quarry blasts are carried out mostly during the day time. Based on this fact a well known method of [1] is implemented, which has the capability of detecting the areas of quarry blast activity. Also, discrimination of quarry blasts from earthquakes has been achieved by studying waveforms at key seismic stations located close to the quarrying area. Further, distinction is achieved through spectral analysis in the frequency band of 3 - 15 Hz. Ratio of day-time to night-time events, waveform pattern and spectral analysis approach confirm the presence of quarry blasts aligned south-east of the Warna reservoir.
文摘Koyna region, a seismically active region, has many time series observations such as seismicity, reservoir water levels, and many bore well water levels. One of these series is used to predict others since these parameters are interlinked. If these series were stationary, we used correlation analysis. However, it is seen that maximum of these time series are nonstationary. In this case, co-integration method is used that is extracted from econometrics and forecast is possible. We have applied this methodology to study time series of reservoir water levels of this region and we find them to be co-integrated. Therefore, forecast of water levels for one of the reservoir is done from the other as these will never drift apart too much. The outcomes demonstrate that a joint modelling of both data sets based on underlying physics resolves to be sparingly useful for understanding predictability issues in reservoir induced seismicity.
文摘Identification of precise hypocenter location is useful in order to improve the faults plane orientation and seismic zone analysis. In the study area, relocated hypocenter of earthquakes in Koyna-Warna region (KWR) from the short period recorded data from 6th January 2010 to 28th May 2010 by using Cross-Correlation waveform results in Double Difference Hypocenter method [1]. The results show the significant improvement in hypocenter location and orientation in earthquake hypocenters, which is correlated with local faults plane orientation in study region. From the observations the earthquake hypocenters are lying in the depth between 3 to 8 km. The result which identified three faults plane orientation in NNW-SSE direction and also identified new fractures in NE-SW directions between the faults plane orientation with short duration data sets the first time in India.
