sentences:  Recent work suggests that compositional variations in the subducting slab may also contribute to double seismic zone , or that DSZs represent the locus of serpentine dehydration in the slab .Bathymetry of the Mariana arc region , showing all 51 edifices presently named along the volcanic front between 12°30’N and 23°10’N.Hydrothermally or volcanically active submarine edifices are labeled red; active subaerial edifices are labeled green.