Molucca Sea
While the scientific community has not come to a consensus as to when the Molucca Sea Plate became fully subducted, the dominant theory is that the Molucca Sea Plate has been completely subducted beneath the overriding Halmahera and Sangihe Plates. When actively subducting, the crustal collision of the Molucca Sea Plate was formed by surface intersection of “oppositely dipping Benioff zones” (also known as divergent double subduction) which results in the Sangihe and Halmahera volcanic arcs. The force exerted by the thick overlying collision complex of the Halmahera and Sangihe Plates effectively depressed the crust of the Molucca Sea Plate. The plate itself features an asymmetrical morphology, configured in an inverted U-shape. The arc-arc collision zone of the Molucca Sea Plate is characterized as a thick, low velocity layer, which is highly variable in density. The variable in density of the Molucca Sea Plate led to different subduction velocities on the two sides. Divergent Double Subduction may facilitate various tectonic processes, including closure of ocean basins, accretion and amalgamation of volcanic arcs, and growth of continents.