Heat flow in the Philippine Sea

Abstract

The distribution of heat flow in the Philippine Sea is very complicated. Unlike other marginal seas behind island arcs and the Pacific Basin proper in front of arcs, the Philippine Sea has neither uniformly high nor low heat flow but shows numerous adjacent areas of high and low heat flow. Contouring is difficult but the pattern of heat flow distribution is fairly well established in the northwestern Philippine Sea, i. e. the area of the western Shikoku Basin and the Ryukyu Trench and Island Arc. The basin and trench southeast of the Ryukyu (Nansei-Shoto) Arc are characterized by low heat flow, and the area behind the arc by high heat flow. This distribution is consistent with the pattern over other trench and island arc systems. There is a well-defined area of high heat flow in the northern Shikoku Basin. Scattered measurements in the eastern part of the Philippine Sea behind the Izu-Bonin (Ogasawara) Arc are also predominantly high, suggesting, that the area of high heat flow in the Shikoku Basin may be part of a broad region of above average heat flow behind this arc. Several measurements west of the Mariana Arc indicate low heat flow in the trough between the outer and inner arcs and above average heat flow west of the inner ridge. Scattered measurements in the Philippine and Parece Vela basins south of latitude 22°N give highly variable results. High values predominate, however, more measurements are required before it can be established that these basins on the whole have significantly above normal heat flow.