Oblique plate convergence along arcuate trenches on a spherical Earth. An example from the Western Sunda Arc

Abstract We propose a new definition of oblique plate convergence. Our model considers arc-trench curvature on spherical Earth, and defines obliquity as the angle between direction convergence azimuth from central point along arc to center arcuate trench. also show how this may be extended multiple-arc trenches. apply Western Sunda Arc, which has been traditionally considered prime example convergence, particularly segment corresponding Sumatra. define eight arc-like segments system. Obliquity angles these vary 92° in northernmost (Burmese) 7° offshore strait (between Sumatra Java). The is 31°, almost within slightly Given low obliquity, partitioning Sumatran fault, southern portion difficult explain by alone. suggest that entire (or forearc) inboard Arc dragged Burmese arc, where overriding subducting plates are completely coupled high.