Seismic tomography with P and S data reveals lateral variations in the rigidity of deep slabs

Citation
S. Widiyantoro et al., Seismic tomography with P and S data reveals lateral variations in the rigidity of deep slabs, EARTH PLAN, 173(1-2), 1999, pp. 91-100
Citations number
35
Categorie Soggetti
Earth Sciences
Journal title
EARTH AND PLANETARY SCIENCE LETTERS
ISSN journal
0012821X → ACNP
Volume
173
Issue
1-2
Year of publication
1999
Pages
91 - 100
Database
ISI
SICI code
0012-821X(19991115)173:1-2<91:STWPAS>2.0.ZU;2-I
Abstract
Regional seismic tomography of the northwest Pacific island arcs using P- a nd S-wave arrival time data with similar path coverage reveals an oceanic l ithospheric slab deflected in the mantle transition zone beneath the Izu Bo nin region in good agreement with the results of earlier tomographic and ot her seismic studies in the region. The S-wave images, however, do not show clearly the deflection of the slab. This implies that the stagnant lithosph eric slab in the transition zone is more likely a bulk-sound structure, whi ch is strongly supported by our results from joint inversions for bulk-soun d and shear wavespeeds. For the Izu Bonin region, where trench migration ha s been reported, the properties of the deflected slab lying on top of the 6 60 km discontinuity show strong bulk-sound and weak shear signatures in con trast to the descending slab itself. There is an indication in the shear im ages that a component of the former oceanic lithosphere is penetrating into the top of the lower mantle, suggesting that a slab split has occurred. (C ) 1999 Elsevier Science B.V. All rights reserved.