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Title: Evidence for Ultra-Low Velocity Zone Genesis in Downwelling Subducted Slabs at the Core–Mantle Boundary
Abstract

We investigate broadband SPdKS waveforms from earthquakes occurring beneath Myanmar. These paths sample the core–mantle boundary beneath northwestern China. Waveform modeling shows that two ∼250 × 250 km wide ultra-low velocity zones (ULVZs) with a thickness of roughly 10 km exist in the region. The ULVZ models fitting these data have large S-wave velocity drops of 55% but relatively small 14% P-wave velocity reductions. This is almost a 4:1 S- to P-wave velocity ratio and is suggestive of a partial melt origin. These ULVZs exist in a region of the Circum-Pacific with a long history of subduction and far from large low-velocity province (LLVP) boundaries where ULVZs are more commonly observed. It is possible that these ULVZs are generated by partial melting of mid-ocean ridge basalt.

 
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Award ID(s):
2216564
PAR ID:
10516186
Author(s) / Creator(s):
; ;
Publisher / Repository:
The Seismological Society of America
Date Published:
Journal Name:
The Seismic Record
Volume:
4
Issue:
2
ISSN:
2694-4006
Page Range / eLocation ID:
111 to 120
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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