EarthRef.org Reference Database (ERR)
Development and Maintenance by the EarthRef.org Database Team

Detailed Reference Information
Ritsema 2000
Ritsema, J. (2000). Evidence for shear velocity anisotropy in the lowermost mantle beneath the Indian Ocean. Geophysical Research Letters 27: doi: 10.1029/1999GL011037. issn: 0094-8276.

Teleseismic recordings (Δ>87¿) of a deep earthquake beneath the Banda Sea at stations in Tanzania show a difference in the arrival time of the radial (SSV) and transverse component (SSH)S wave ranging from 1--3 s. Shear velocity anisotropy in the lowermost mantle beneath the Indian Ocean is the likely cause of this signal because recordings at the same stations of closer-in events (Δ<80¿) in the same source region do not present a comparable differential travel time. For the Banda Sea event, the SSH signals are broader than SSV signals, suggesting that a discontinuity (or strong vertical gradient) in primarily VSH marks the sudden onset of transverse isotropy in D (with a magnitude of 1.4--2.7%) about 350 km above the coremantle boundary. SKKS coda, S-to-p converted phases at the Moho, and upper mantle heterogeneity beneath the stations obscure the onset of SSV and complicate wave shapes. It is therefore difficult to evaluate whether general anisotropy needs to be invoked into a model of shear velocity anisotropy. ¿ 2000 American Geophysical Union

BACKGROUND DATA FILES

Abstract

Keywords
Seismology, Core and mantle
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
2000 Florida Avenue N.W.
Washington, D.C. 20009-1277
USA
1-202-462-6900
1-202-328-0566
service@agu.org
Click to clear formClick to return to previous pageClick to submit