In the present study, the temporal behavior of 2001 Bhuj aftershock sequence in Kachchh region of western peninsular India is studied by the modified Omori law. The Omori law parameters p, c and K are determined with ...In the present study, the temporal behavior of 2001 Bhuj aftershock sequence in Kachchh region of western peninsular India is studied by the modified Omori law. The Omori law parameters p, c and K are determined with the standard errors by the maximum likelihood estimates using ZMAP algorithm in MatLab environment. The entire aftershock sequence is analyzed by diving it into three separate series with respect to time to weigh up the bigger earthquake of magnitude M 5.7 occurring on March 7, 2006 at Gedi fault. This study helps to understand the cumulative effect of the aftershocks generated by this bigger earthquake of the mainshock sequence. The results of this analysis are discussed with other studies of the different earthquake sequence for the different parts of the world and suggest that all the three series of Bhuj aftershock sequence follow the Omori relation. Values of parameter p vary significantly from series 1 to series 3, i.e., p-value varies significantly with time. Similarly, other two Omori law parameters K and c are also found to change significantly with time. These parameters are useful to describe temporal behavior of aftershocks and to forecast aftershock activity in time domain. Aftershock decay rate provides insight into stress release processes after the mainshock, thus helping to understand the heterogeneity of the fault zone properties and evaluate time-dependent seismic hazard analysis over the region.展开更多
Study of source parameters of small to moderate and large earthquakes is important to understand the differences and similarities between dynamic ruptures of different earthquakes and clarifying the scaling relations....Study of source parameters of small to moderate and large earthquakes is important to understand the differences and similarities between dynamic ruptures of different earthquakes and clarifying the scaling relations. In the present study, we have characterized source parameters and presented new and revised empirical relationships between various source parameters for Kachchh region of Gujarat, India to facilitate to draw first-order conclusions regarding the trends in the region. We have studied total 202 aftershocks of shallow-focus (hypo central depth less than 40 km) and moderate magnitude recorded over the Kachchh region during January 2001 to December 2012 by different seismological observatories of India Meteorological Department. We have adopted the spectral technique for source parameter estimation, where S-wave displacement spectra are considered and applied Fast Fourier Transform (FFT) to compute displacement spectra. We have followed the Brune’s source model for our estimation and the estimated values of source parameters show close approximation to the global values. While derived empirical relations between different source parameters, they demonstrate direct or inverse proportion to linear or power scale. Interrelation between seismic moment, rupture parameters, corner frequency and radiated seismic energy can be summarized as , , and ER μ M0 and ER μ Mw for our analysis. Stress drop distribution over the Kachchh region is very scattered and due to its peculiar behavior, it is difficult to derive its empirical relation with other source parameters. Sufficient accuracy on measuring source parameters like corner frequency stress drop, rupture dimensions, radiated seismic energy etc. helps to understand earthquake processes in the region. This is the first ever attempt to establish empirical relation between different source parameters for Kachchh region for longer aftershock sequence and they are useful to assess future earthquake potential over the region.展开更多
A wide band (1000 - 0.001 Hz) magnetotelluric study has been taken up in the Bhuj earthquake epicentral zone and 21 sites have been occupied along three profiles during March-April 2001 to understand the deep structur...A wide band (1000 - 0.001 Hz) magnetotelluric study has been taken up in the Bhuj earthquake epicentral zone and 21 sites have been occupied along three profiles during March-April 2001 to understand the deep structure of the region. In addition the region surrounding Bhuj has been probed earlier with number of MT profiles and the subsurface structure is well constrained from hydrocarbon exploration point of view besides seismotectonic studies. In the present study, the results obtained along 130 km long profile from Mundra to Rapar oriented in NE-SW direction passing through the epicenter are presented considering these two databases. The subsurface structure has shown interesting correlation with the surface deformations, a new basement configuration and associated seismotectonics of the region. Our main result is relating the basement configuration and surface ruptures.展开更多
Earthquake 2001 in Bhuj region of Kachchh district of Gujarat(India) was one of the most devastating earthquakes in the Indian history. This earthquake has caused severe damage to human life and properties. The impact...Earthquake 2001 in Bhuj region of Kachchh district of Gujarat(India) was one of the most devastating earthquakes in the Indian history. This earthquake has caused severe damage to human life and properties. The impact of earthquake on groundwater resources at many locations was significant. Steep rise in static water level due to earthquake was observed at Bhachau and Chandarani. At other location groundwater followed the declining trend.展开更多
文摘In the present study, the temporal behavior of 2001 Bhuj aftershock sequence in Kachchh region of western peninsular India is studied by the modified Omori law. The Omori law parameters p, c and K are determined with the standard errors by the maximum likelihood estimates using ZMAP algorithm in MatLab environment. The entire aftershock sequence is analyzed by diving it into three separate series with respect to time to weigh up the bigger earthquake of magnitude M 5.7 occurring on March 7, 2006 at Gedi fault. This study helps to understand the cumulative effect of the aftershocks generated by this bigger earthquake of the mainshock sequence. The results of this analysis are discussed with other studies of the different earthquake sequence for the different parts of the world and suggest that all the three series of Bhuj aftershock sequence follow the Omori relation. Values of parameter p vary significantly from series 1 to series 3, i.e., p-value varies significantly with time. Similarly, other two Omori law parameters K and c are also found to change significantly with time. These parameters are useful to describe temporal behavior of aftershocks and to forecast aftershock activity in time domain. Aftershock decay rate provides insight into stress release processes after the mainshock, thus helping to understand the heterogeneity of the fault zone properties and evaluate time-dependent seismic hazard analysis over the region.
文摘Study of source parameters of small to moderate and large earthquakes is important to understand the differences and similarities between dynamic ruptures of different earthquakes and clarifying the scaling relations. In the present study, we have characterized source parameters and presented new and revised empirical relationships between various source parameters for Kachchh region of Gujarat, India to facilitate to draw first-order conclusions regarding the trends in the region. We have studied total 202 aftershocks of shallow-focus (hypo central depth less than 40 km) and moderate magnitude recorded over the Kachchh region during January 2001 to December 2012 by different seismological observatories of India Meteorological Department. We have adopted the spectral technique for source parameter estimation, where S-wave displacement spectra are considered and applied Fast Fourier Transform (FFT) to compute displacement spectra. We have followed the Brune’s source model for our estimation and the estimated values of source parameters show close approximation to the global values. While derived empirical relations between different source parameters, they demonstrate direct or inverse proportion to linear or power scale. Interrelation between seismic moment, rupture parameters, corner frequency and radiated seismic energy can be summarized as , , and ER μ M0 and ER μ Mw for our analysis. Stress drop distribution over the Kachchh region is very scattered and due to its peculiar behavior, it is difficult to derive its empirical relation with other source parameters. Sufficient accuracy on measuring source parameters like corner frequency stress drop, rupture dimensions, radiated seismic energy etc. helps to understand earthquake processes in the region. This is the first ever attempt to establish empirical relation between different source parameters for Kachchh region for longer aftershock sequence and they are useful to assess future earthquake potential over the region.
文摘A wide band (1000 - 0.001 Hz) magnetotelluric study has been taken up in the Bhuj earthquake epicentral zone and 21 sites have been occupied along three profiles during March-April 2001 to understand the deep structure of the region. In addition the region surrounding Bhuj has been probed earlier with number of MT profiles and the subsurface structure is well constrained from hydrocarbon exploration point of view besides seismotectonic studies. In the present study, the results obtained along 130 km long profile from Mundra to Rapar oriented in NE-SW direction passing through the epicenter are presented considering these two databases. The subsurface structure has shown interesting correlation with the surface deformations, a new basement configuration and associated seismotectonics of the region. Our main result is relating the basement configuration and surface ruptures.
文摘Earthquake 2001 in Bhuj region of Kachchh district of Gujarat(India) was one of the most devastating earthquakes in the Indian history. This earthquake has caused severe damage to human life and properties. The impact of earthquake on groundwater resources at many locations was significant. Steep rise in static water level due to earthquake was observed at Bhachau and Chandarani. At other location groundwater followed the declining trend.
