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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS014 Poster presentation 2301
Seismotectonics of Makran subduction zone
Dr. Kirti Srivastava
Fractals in Geophysics National Geophysics Research Institute IASPEI
V P Dimri
The seismicity patterns of Makran subduction zone has been analyzed by using the data of epicenters
obtained from NEIC catalog for the duration of 1973-2005. All the earthquake magnitudes are body
wave magnitudes ( Mb). The minimum magnitude of the earthquakes is 4.0 whilst the maximum
magnitude is 6.5. However, the focal depths of these earthquakes are not accurate as these have been
located by global stations and hence, most of them are fixed at 33 km. The salient feature which is
conspicuous from this analysis is the absence of shallow seismicity in western Makran whilst the eastern
Makran has shallow interplate seismicity and coincides with the major deformation zone. The variation
in b-value can be related to the stress distribution after the main-shock, as well as the history of
previous ruptures. The regions with lower values of b are probably the regions under higher applied
shear stress whereas the regions with higher values of b are the areas that experienced the slip or
having lower stresses. From our study using the NEIC earthquake catalog the b-values have been
separately estimated for the eastern and western segments. It is seen from the b-values that the
eastern segment has a lower b-value and a higher fractal dimension whilst the western is in contrast
with the b-value higher and lower fractal dimension.
Keywords: makran, b value, fractal dimension