The above diagram shows a plate reconstruction for the OJP's position relative to the Solomon Islands for the past 0-15 Ma. The colored outline of the plateau represents its present day areal extent and does not account for those parts which have previously been subducted or accreted to the Malaita Accretionary Prism (MAP).
Prior to the Late Miocene, the Pacific plate was subducting to the southwest beneath the Australian plate. At around 6-8 Ma, the southern edge of the OJP arrived at the North Solomon Trench (NST). As thicker sections of the plateau entered the trench, the OJP began to resist subduction. The increased coupling between the Pacific plate and the island arc initiated a subduction zone polarity reversal as the Australian plate began to subduct to the northeast at the San Cristobal Trench.
Although most of the Pliocene plate convergence was accomodated at the San Cristobal trench, subduction of the Pacific plate continued with the 2-4 Ma emergence of the islands of Ulawa, Malaita, and the northern part of Santa Isabel. Present day plate motions show active subduction on both sides of the arc with the degree of plateau accretion and deformation dcreasing to the northwest along the MAP as the OJP impinges from the east.
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gravity and hypocenter profiles of the region
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