CORALS AS PROXY RECORDERS OF VOLCANIC ACTIVITY - EVIDENCE FROM BANDA-API, INDONESIA

Corals growing on the flanks of Banda Api, Indonesia, contain records of volcanic activity which occurred in May, 1988. Ashfall killed porti ons of some massive coral colonies (Porites lobata), resulting in the formation of death surfaces. These surfaces were preferential sites fo r extensive bioerosion and incorporation of volcanic ash into underlyi ng skeletal pores. Subsequent coral regeneration resulted in the prese rvation of death/regrowth surfaces overlying trapped volcanic ash. An orange-colored iron-rich chemical precipitate is preserved in the skel etons of corals which survived the volcanic event. These distinct oran ge bands are contemporaneous with the death/regrowth surfaces. The iro n banding is interpreted as being a product of hydrothermal activity w hich accompanied volcanism. X-radiographs of coral skeletons confirm t hat the timing of formation of both the death surfaces and the orange banding is coincident with the 1988 eruption. The features preserved i n these corals may be valuable proxy indicators of volcanic events in analogous recent and ancient environments.