TECTONIC HISTORY OF THE NORTHERN PERU CONVERGENT MARGIN DURING THE PAST 400-KA

The late Pleistocene tectonic history of the northern Peru convergent margin can be retraced using data collected during deep-sea dives of t he submersible Nautile combined with a recent Hydrosweep survey conduc ted off Peru at lat 5-degrees-6-degrees-S by the R/N Sonne. During the past 400 ka, a broad rollover fold formed in the middle slope area, i n association with a major seaward-dipping detachment fault. A catastr ophic debris avalanche occurred as the result of oversteepening of the landward flank of the rollover fold. The gravity failure of the slope , previously recognized by SeaBeam mapping, occurred at 13.8 +/- 2.7 k a and produced a destructive tsunami.