Abstract
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.
Highlights
Hazard analysis involved with seismic activity is based on the estimation of the future earthquake potential in a given region
The future earthquake potential of a fault is evaluated from estimates of fault rupture parameters which are directly related to earthquake magnitude
Errors associated in estimation of source parameters can be represented by standard deviation and mean values
Summary
Hazard analysis involved with seismic activity is based on the estimation of the future earthquake potential in a given region. The future earthquake potential of a fault is evaluated from estimates of fault rupture parameters which are directly related to earthquake magnitude. Source parameters of small to moderate and large earthquakes are important for understanding the differences and similarities between dynamic ruptures of small and large earthquakes and clarifying the scaling relations. It is often difficult to accurately determine source parameters of small earthquakes because relatively high-frequency seismic waves excited by small earthquakes are scattered and attenuated along the path. Many researchers have published their studies on source parameters for different regions of the world [1]-[4]. The source parameters discussed most often are seismic moment M0, moment magnitude Mw, stress drop Δσ, corner frequency fc and rupture area A. We have interrelated some of these parameters on the basis of assumptions of similarity and scaling and spectral source theories
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