Abstract:
Himalaya is the one of the youngest mountain belt having active tectonic discontinuities,
complex geological setup, and zones of variable seismic density. The western part of
Himalaya faced catastrophe due to great Kangra earthquake (32.3oN, 76.25oE) of April 4,
1905 of magnitude 8 and the recently occurred Mw 7.6 Muzaffarabad earthquake of
October 8, 2005.The process of removing the group of dependent earthquakes events, form
the seismicity catalog, is termed 'declustering' of seismic catalog. There are many available
declustering algorithms that have been proposed over the years but, most users have use
either the algorithm of Gardner and Knopoff (1974) or Reasenberg (1985). The
incompleteness of an earthquake dataset that comes in because of the non-uniformity of
the seismic networks with time is investigated generally by fitting a Gutenberg-Richter
model to the frequency magnitude distribution (FMD). The FMD described the
relationship between the frequency of occurrence and magnitude of earthquakes
as 𝑙𝑜𝑔𝑁(𝑀) = 𝑎 โ 𝑏(𝑀). However, in practice as said earlier the available catalogs of
earthquakes are not complete particularly for smaller magnitude events i.e. catalog is
biased against small events. Objective of this work is declustering of Merged
Homogenized earthquake catalog of study area, Estimation of a value, b value and
Magnitude of completeness (Mc) of Merged Homogenized catalog (MH Catalog) and
Merged Homogenized Declustered (MHD Catalogs) catalogs, calculation of return period
of earthquake for several magnitudes, completeness analysis of MH Catalog and MHD
Catalog, division study area into seismic source zones and Estimation of a value, b value,
Magnitude of completeness (Mc) and return period.
