RT Journal Article
SR Electronic
T1 Deep slab seismicity limited by rate of deformation in the transition zone
JF Science Advances
JO Sci Adv
FD American Association for the Advancement of Science
SP eaaz7692
DO 10.1126/sciadv.aaz7692
VO 6
IS 22
A1 Billen, Magali I.
YR 2020
UL http://advances.sciencemag.org/content/6/22/eaaz7692.abstract
AB Deep earthquakes within subducting tectonic plates (slabs) are enigmatic because they appear similar to shallow earthquakes but must occur by a different mechanism. Previous attempts to explain the depth distribution of deep earthquakes in terms of the temperature at which possible triggering mechanisms are viable, fail to explain the spatial variability in seismicity. In addition to thermal constraints, proposed failure mechanisms for deep earthquakes all require that sufficient strain accumulates in the slab at a relatively high stress. Here, I show that simulations of subduction with nonlinear rheology and compositionally dependent phase transitions exhibit strongly variable strain rates in space and time, which is similar to observed seismicity. Therefore, in addition to temperature, variations in strain rate may explain why there are large gaps in deep seismicity (low strain rate), and variable peaks in seismicity (bending regions), and, possibly, why there is an abrupt cessation of seismicity below 660 km.