Subducting slab ultra-slow velocity layer coincident with silent earthquakes in southern Mexico.
Great earthquakes have repeatedly occurred on the plate interface in a few shallow-dipping subduction zones where the subducting and overriding plates are strongly locked. Silent earthquakes (or slow slip events) were recently discovered at the down-dip extension of the locked zone and interact with the earthquake cycle. Here, we show that locally observed converted SP arrivals and teleseismic underside reflections that sample the top of the subducting plate in southern Mexico reveal that the ultra-slow velocity layer (USL) varies spatially (3 to 5 kilometers, with an S-wave velocity of approximately 2.0 to 2.7 kilometers per second). Most slow slip patches coincide with the presence of the USL, and they are bounded by the absence of the USL. The extent of the USL delineates the zone of transitional frictional behavior.
Song
Teh-Ru Alex
TR
Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road N.W., Washington, DC 20015, USA. asong@ciw.edu
Helmberger
Donald V
DV
Brudzinski
Michael R
MR
Clayton
Robert W
RW
Davis
Paul
P
Pérez-Campos
Xyoli
X
Singh
Shri K
SK