The Aftershock Signature of Supershear Earthquakes
Michel Bouchon1* and
Hayrullah Karabulut2
Recent studies show that earthquake faults may rupture at speeds
exceeding the shear wave velocity of rocks. This supershear
rupture produces in the ground a seismic shock wave similar
to the sonic boom produced by a supersonic airplane. This shock
wave may increase the destruction caused by the earthquake.
We report that supershear earthquakes are characterized by a
specific pattern of aftershocks: The fault plane itself is remarkably
quiet whereas aftershocks cluster off the fault, on secondary
structures that are activated by the supershear rupture. The
post-earthquake quiescence of the fault shows that friction
is relatively uniform over supershear segments, whereas the
activation of off-fault structures is explained by the shock
wave radiation, which produces high stresses over a wide zone
surrounding the fault.
2 Kandilli Observatory and Earthquake Research Institute, Bogaziçi University, Istanbul Kandilli Observatory, 81220 Cengelköy, Istanbul.
* To whom correspondence should be addressed. E-mail: Michel.Bouchon{at}ujf-grenoble.fr
