Piip

Dredged rocks from the summits of volcanic cones rising from 2,500 m depth to within a few hundred meters of the surface yielded dacitic lavas and pumice apparently of Holocene age (Fedotov et al. , 1989; Seliverstov et al. , 1986).

Tephrochronological studies on the Commander Islands suggest that the latest tephras from Piip volcano may be as young as a few centuries, and echograms indicate present-day gas emission from the volcano. The three steep-sided volcanic cones were constructed along a N-S trend and lie about 140-150 km from the axis of the Aleutian trench, a similar distance as other Aleutian arc volcanoes. The southern and northern cones exceed the central cone in size and have craters open to the SW about 500 and 300 m wide, respectively.

A lava dome occupies the southern crater, and other domes or cones are found on the summit cones and flanks of the edifice. Vigorous gas emission from the northern cone rises about 300 m from "black smoker" vents on the crater floor.