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Search for lower mantle high‐velocity zones beneath the deepest Kuril and Mariana earthquakes
Author(s) -
Okano Kenta,
Suetsugu Daisuke
Publication year - 1992
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/92gl00366
Subject(s) - geology , subduction , slab , seismology , mantle (geology) , mantle wedge , transition zone , residual , arrival time , crust , geodesy , geophysics , tectonics , algorithm , computer science , engineering , transport engineering
We perform travel time analyses for the Kuril and the Mariana subduction zones to investigate whether a lower mantle high‐velocity zone exists immediately beneath the deepest earthquakes in these regions. We use P and PKIKP wave arrival time data read directly and accurately from WWSSN short‐period vertical component records and corrected for the effect of lateral heterogeneity far from the source regions using a differential residual sphere technique. The corrected residuals for the deep Kuril events show that a high velocity zone extends in the down‐dip direction of the Kuril slab in the lower mantle. On the other hand, the residuals for the deep Mariana events show no evidence for a high‐velocity zone in the down‐dip direction beneath the deepest earthquakes. A reasonable interpretation of these results is that the Kuril slab penetrates into the lower mantle (h≥670 km) but that the Mariana slab does not extend vertically into the lower mantle.