Chen, P., E. A. Okal, and C. R. Bina, Correlations of convergence rates and oblique subduction with intermediate-depth seismic moment release and dip angles in the western Pacific, Eos, Transactions of the American Geophysical Union, 82, Fall Meeting Supplement, S51A-0592, 2001.
The northwestward subduction of the Pacific plate underneath the Philippine Sea plate exhibits significant along-strike variations both in rate and obliquity. To investigate their effects, we compile intermediate-depth earthquakes (~70-300 km) from relocated earthquake hypocenters (Engdahl et al., 1998) to determine the regional slab strike and dip angles along the Izu-Bonin-Mariana arc, and we calculate regional seismic moment release from the Harvard CMT catalogue. The strike derived is used to estimate the degree of oblique subduction. The dip angles determined are between 40 degrees and 60 degrees, becoming steeper from north to south, except for the southernmost part of the Mariana arc (44 degrees). We observe that dip angles correlate positively with both degree of oblique subduction and seismic moment release but negatively with plate convergence rate, where seismic moment release exhibits the weaker of these correlations. We also observe spatial variations in the clustering of principal stress axes of seismicity.Copyright © 2001 American Geophysical Union