The inverse Omori law for foreshocks discovered in the 1970s states that the rate of earthquakes prior to a mainshock increases on average as a power law ∝ 1/(tc − t) p ′ of the time to the mainshock occurring at tc. Here, we show that this law results from the direct Omori law for aftershocks describing the power law decay ∼ 1/(t − tc) p of seismicity after an earthquake, provided that any ear...

in this study, the 2005 dahuieh (zarand) locally recorded aftershock sequence has been analyzed. having the distribution of aftershocks and the source extension, a w-e trending near vertical faulting with an extension of about 15-20 km could be estimated. the rupture causing the powerful dahuieh earthquake apparently initiated in the modified epicentric area and propagated unilaterally towards ...

The occurrence of aftershocks is a signature of physical systems exhibiting relaxation phenomena. They are observed in various natural or experimental systems and usually obey several non-trivial empirical laws. Here we consider a cellular automaton realization of a nonlinear viscoelastic slider-block model in order to infer the physical mechanisms of triggering responsible for the occurrence o...

We use time-domain pulse widths to estimate static stress drops for 279 M L 2.5 to 4.0 aftershocks of the 17 January 1994, M w 6.7 Northridge, California, earthquake. The stress drops obtained range from 0.02 to 40 bars, with a log average of 0.75 bar. Error bars computed for our estimates are typically a factor of 5, indicating that the three order of magnitude scatter in stress drops is not s...

Analyzing diverse seismic catalogs, we have determined that the probability densities of the earthquake recurrence times for different spatial areas and magnitude ranges can be described by a unique universal distribution if the time is rescaled with the rate of seismic occurrence, which therefore fully governs seismicity. The shape of the distribution shows the existence of clustering beyond t...