  We study earthquake interval time statistics, paying special attention to
inter-occurrence times in the two-dimensional (2D) stick-slip (block-slider)
model. Inter-occurrence times are the time interval between successive
earthquakes on all faults in a region. We select stiffness and friction
parameters as tunable parameters because these physical quantities are
considered as essential factors in describing fault dynamics. It is found that
inter-occurrence time statistics depend on the parameters. Varying stiffness
and friction parameters systematically, we optimize these parameters so as to
reproduce the inter-occurrence time statistics in natural seismicity. For an
optimal case, earthquakes produced by the model obey the Gutenberg-Richter law,
which states that the magnitude-frequency distribution exhibits the power law
with an exponent approximately unity.
