Role of multifractal analysis in understanding the preparation zone for large size earthquake in the North-Western Himalaya region

Abstract

Seismicity has power law in space, time and magnitude distributions and same is expressed by the fractal dimension D' Omori's exponent p and b value. The spatio-temporal patterns of epicenters have heterogeneous characteristics. As the crust gets self-organised into critical state, the spatio-temporal clustering of epicenters emerges to heterogeneous nature of seismicity. To understand the heterogeneous characteristics of seismicity in a region, multifractal studies hold promise to characterise the dynamics of region. Multifractal study is done on seismicity data of the North-Western Himalaya region which mainly involve seismogenic region of 1905 Kangra great earthquake in the North-Western Himalaya region. The seismicity data obtained from USGS catalogue for time period 1973-2009 has been analysed for the region which includes the October 2005 Muzafrabad-Kashmir earthquake (Mw=7.6) Significant changes have been observed in generalised dimension D q,Dq spectra and b-value. The significant temporal changes in generalised dimension Dq,b-value and Dq-q spectra prior to occurrence of Muzaffrabad-Kashmir earthquake relates to distribution of epicenters in the region. The decrease in generalised dimension and b-value observed in our study show the relationship with the clustering of seismicity as is expected in self-organised criticality behaviour of earthquake occurrences. Such study may become important in understanding the preparation zone of large and great size earthquake in various tectonic regions. © 2011 Author(s).