Repeating Deep Earthquakes: Evidence for Fault Reactivation at Great Depth
Douglas A. Wiens,
Nathaniel O. Snider
We have identified three groups of deep earthquakes showing nearly
identical waveforms in the Tonga slab. Relocation with a
cross-correlation method shows that each cluster is composed of 10 to
30 earthquakes along a plane 10 to 30 kilometers in length. Some of the
earthquakes are colocated, demonstrating repeated rupture of the same
fault, and one pair of events shows identical rupture complexity,
suggesting that the temporal and spatial rupture pattern was repeated.
Recurrence intervals show an inverse time distribution, indicating a
strong temporal control over fault reactivation. Runaway thermal shear
instabilities may explain temporally clustered earthquakes with similar
waveforms located along slip zones weakened by shear heating.
Earthquake doublets that occur within a few hours are consistent with
events recurring before the thermal energy of the initial rupture can
diffuse away.
Department of Earth and Planetary Sciences, Washington University,
St. Louis, MO 63130, USA.
Department of Earth and Planetary Sciences, Washington University,
St. Louis, MO 63130, USA.
