  Earthquakes and aftershock sequences follow several empirical scaling laws:
One of these laws is Bath's law for the magnitude of the largest aftershock. In
this work, Modified Form of Bath's Law and its application to KOERI data have
been studied. Bath's law states that the differences in magnitudes between
mainshocks and their largest detected aftershocks are approximately constant,
independent of the magnitudes of mainshocks and it is about 1.2. In the
modified form of Bath's law for a given mainshock we get the inferred largest
aftershock of this mainshock by using an extrapolation of the Gutenberg-Richter
frequency-magnitude statistics of the aftershock sequence. To test the
applicability of this modified law, 6 large earthquakes that occurred in Turkey
between 1950 and 2004 with magnitudes equal to or greater than 6.9 have been
considered. These earthquakes take place on the North Anatolian Fault Zone.
Additionally, in this study the partitioning of energy during a
mainshock-aftershock sequence was also calculated in two different ways. It is
shown that most of the energy is released in the mainshock. The constancy of
the differences in magnitudes between mainshocks and their largest aftershocks
is an indication of scale-invariant behavior of aftershock sequences.
