Pj. Hill et Dl. Tiffin, GEOLOGY, SEDIMENT PATTERNS, AND WIDESPREAD DEFORMATION ON THE SEA-FLOOR OFF WESTERN-SAMOA REVEALED BY WIDE-SWATH IMAGERY, Geo-marine letters, 13(2), 1993, pp. 116-125
GLORIA and SeaMARC II sea-floor images of offshore Western Samoa revea
l large-scale mass movements, volcanism, and structural modification.
These processes are driven by hot-spot mantle diapirism and nearby pla
te subduction. Debris avalanche deposits extend from the island slope
onto the adjacent abyssal plains, covering at least 20,000 km2. Sedime
nt flows occur in sheets up to 30 km wide; slump structures are common
on steep slopes. Volcanic cones and lava sheets are evident on lower
slopes and abyssal plains. Major volcanic rift zones on the island of
Savaii continue offshore. Subduction-induced flexure has produced inte
nse tensional fracturing on the outer wall of the Tonga Trench.