TY - JOUR
T1 - Anisotropy in the subducting slab
T2 - Observations from Philippine Sea plate events in Taiwan
AU - Chen, Kate Huihsuan
AU - Tseng, Yu Lung
AU - Furumura, Takashi
AU - Kennett, Brian L.N.
PY - 2015/12/16
Y1 - 2015/12/16
N2 - In the southernmost Ryukyu subduction zone, slab-guiding behavior from intermediate-depth earthquakes is well documented with a low-frequency (<2 Hz) first P arrival followed by sustained high-frequency (3-10 Hz) wave trains. Such waves developed by propagating along a long path within the slab are expected to have high sensitivity to anisotropy within the slab. We determine shear wave splitting parameters from 178 intraplate events that are deeper than 100 km. The possible slab-anisotropy-associated polarization pattern shows the fast direction at N65°E and delay time of 0.13-0.45 s. This is stronger than the previously documented crust effect (<0.1 s), similar to the mantle wedge effect (0.28 s in average), but weaker than the upper mantle effect (1.3 s in average) in Taiwan. The fast axis reflects the fossil spreading direction of Philippine Sea plate with minor clockwise rotation due to the collision to Eurasian plate.
AB - In the southernmost Ryukyu subduction zone, slab-guiding behavior from intermediate-depth earthquakes is well documented with a low-frequency (<2 Hz) first P arrival followed by sustained high-frequency (3-10 Hz) wave trains. Such waves developed by propagating along a long path within the slab are expected to have high sensitivity to anisotropy within the slab. We determine shear wave splitting parameters from 178 intraplate events that are deeper than 100 km. The possible slab-anisotropy-associated polarization pattern shows the fast direction at N65°E and delay time of 0.13-0.45 s. This is stronger than the previously documented crust effect (<0.1 s), similar to the mantle wedge effect (0.28 s in average), but weaker than the upper mantle effect (1.3 s in average) in Taiwan. The fast axis reflects the fossil spreading direction of Philippine Sea plate with minor clockwise rotation due to the collision to Eurasian plate.
KW - Philippine Sea plate
KW - shear wave splitting
KW - slab anisotropy
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U2 - 10.1002/2015GL066227
DO - 10.1002/2015GL066227
M3 - Article
AN - SCOPUS:84953637495
VL - 42
SP - 10248
EP - 10255
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 23
ER -