Santosh Sundriyal - Academia.edu (original) (raw)

Papers by Santosh Sundriyal

Journal of Asian Earth …, 2012

a b s t r a c t During the 1st decade of the 21st century, the study area of Talala, Saurashtra o... more a b s t r a c t During the 1st decade of the 21st century, the study area of Talala, Saurashtra of western India witnessed three damaging earthquakes of moderate magnitude, year 2007 [Mw 5.0; Mw 4.8] and in the year 2011 [Mw 5.1] that generated public panic in the region. The last damaging moderate earthquake of the 20th October 2011 in Talala region (21.09°N;70.45°E), located at about 200 km south to the devastating 2001 Bhuj (23.412°N, 70.232°E) mainshock (Mw 7.6), jolted the entire Saurashtra region of Gujarat.

Tectonophysics, 2012

The attenuation characteristics based on coda waves of Mainland Gujarat (India) has been investig... more The attenuation characteristics based on coda waves of Mainland Gujarat (India) has been investigated in the present study. The broadband waveforms of 53 local earthquakes (Mw 1.1 -3.3) having focal depths in the 6.0-33.6 km range recorded at five stations of Mainland Gujarat region has been used for the analysis. The frequency -dependent relationships (Q=Q 0 f n ) for coda-Q (Q c ) and dependency of coda-Q on lapse time windows have been determined for the said region. The average lapse time dependent coda-Q relations estimated for the region are: Q c =(87±13)f (1.01±0.06) (lapse time : 30 s), Q c =(112±20)f (0.94±0.08) (lapse time : 40 s) and Q c =(120±22)f (0.76±0.07) (lapse time : 50 s). The increase in Q c values with lapse time shows the depth dependence of Qc as longer lapse time windows will sample larger area. The observed quality factor is strongly dependent on frequency and lapse time, which indicates that the upper lithosphere, is more heterogeneous and seismotectonically active, while the lower lithosphere is homogeneous and relatively less active. A comparison of the coda-Q estimated for Mainland Gujarat region with those of nearby Kachchh and Saurashtra regions shows that Mainland Gujarat region is more heterogeneous. The rate of decay of attenuation (Q -1 ) with frequency for the relations obtained here is found to be comparable with those of A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 other regions of the world though the absolute values differ The obtained relations are expected to be useful for the estimation of source parameters of the earthquakes in the Mainland Gujarat region where no such relations were available earlier. These relations are also important for the simulation of earthquake strong ground motions in the region.

Geomatics, Natural Hazards and Risk, 2012

The Gujarat state seismic network (GSNet), comprising of 50 broadband seismograph (BBS) stations ... more The Gujarat state seismic network (GSNet), comprising of 50 broadband seismograph (BBS) stations and 40 strong motion accelerographs (SMAs), has been operated and maintained by the Institute of Seismological Research (ISR) since 2006. Nineteen permanent BBS stations are connected through VSAT and the rest are kept in an offline mode. The local geology beneath seismic stations varies from Mesozoic to Quaternary formations. The seismic background noise (SBN) at these stations was calculated and found that it varies widely as a function of period, time and geographic location. We have studied the SBN variation along these three parameters for 14 online BBS stations of the GSNet. It was found that the stations located on the Deccan trap and Mesozoic formations are good sites with low SBN while stations on Quaternary, Tertiary and soft soil are noisy. The comparison between day and night noise spectra shows that SBN increases during the daytime at most of the stations. Three typical noisy peaks at three different periods were recorded at all of the stations, which is a global phenomenon. The results of this study will be helpful in selecting sites for future earthquake observations.

Journal of Asian Earth …, 2012

a b s t r a c t During the 1st decade of the 21st century, the study area of Talala, Saurashtra o... more a b s t r a c t During the 1st decade of the 21st century, the study area of Talala, Saurashtra of western India witnessed three damaging earthquakes of moderate magnitude, year 2007 [Mw 5.0; Mw 4.8] and in the year 2011 [Mw 5.1] that generated public panic in the region. The last damaging moderate earthquake of the 20th October 2011 in Talala region (21.09°N;70.45°E), located at about 200 km south to the devastating 2001 Bhuj (23.412°N, 70.232°E) mainshock (Mw 7.6), jolted the entire Saurashtra region of Gujarat.

Tectonophysics, 2012

The attenuation characteristics based on coda waves of Mainland Gujarat (India) has been investig... more The attenuation characteristics based on coda waves of Mainland Gujarat (India) has been investigated in the present study. The broadband waveforms of 53 local earthquakes (Mw 1.1 -3.3) having focal depths in the 6.0-33.6 km range recorded at five stations of Mainland Gujarat region has been used for the analysis. The frequency -dependent relationships (Q=Q 0 f n ) for coda-Q (Q c ) and dependency of coda-Q on lapse time windows have been determined for the said region. The average lapse time dependent coda-Q relations estimated for the region are: Q c =(87±13)f (1.01±0.06) (lapse time : 30 s), Q c =(112±20)f (0.94±0.08) (lapse time : 40 s) and Q c =(120±22)f (0.76±0.07) (lapse time : 50 s). The increase in Q c values with lapse time shows the depth dependence of Qc as longer lapse time windows will sample larger area. The observed quality factor is strongly dependent on frequency and lapse time, which indicates that the upper lithosphere, is more heterogeneous and seismotectonically active, while the lower lithosphere is homogeneous and relatively less active. A comparison of the coda-Q estimated for Mainland Gujarat region with those of nearby Kachchh and Saurashtra regions shows that Mainland Gujarat region is more heterogeneous. The rate of decay of attenuation (Q -1 ) with frequency for the relations obtained here is found to be comparable with those of A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 other regions of the world though the absolute values differ The obtained relations are expected to be useful for the estimation of source parameters of the earthquakes in the Mainland Gujarat region where no such relations were available earlier. These relations are also important for the simulation of earthquake strong ground motions in the region.

Geomatics, Natural Hazards and Risk, 2012

The Gujarat state seismic network (GSNet), comprising of 50 broadband seismograph (BBS) stations ... more The Gujarat state seismic network (GSNet), comprising of 50 broadband seismograph (BBS) stations and 40 strong motion accelerographs (SMAs), has been operated and maintained by the Institute of Seismological Research (ISR) since 2006. Nineteen permanent BBS stations are connected through VSAT and the rest are kept in an offline mode. The local geology beneath seismic stations varies from Mesozoic to Quaternary formations. The seismic background noise (SBN) at these stations was calculated and found that it varies widely as a function of period, time and geographic location. We have studied the SBN variation along these three parameters for 14 online BBS stations of the GSNet. It was found that the stations located on the Deccan trap and Mesozoic formations are good sites with low SBN while stations on Quaternary, Tertiary and soft soil are noisy. The comparison between day and night noise spectra shows that SBN increases during the daytime at most of the stations. Three typical noisy peaks at three different periods were recorded at all of the stations, which is a global phenomenon. The results of this study will be helpful in selecting sites for future earthquake observations.