The ice cap is approximately thick on average. It is thickest in parts of the summit plateau and under the Nereides Glacier on the southwestern slopes, where it is as deep as . Glaciers on the northern and, to a lesser extent, the eastern slopes lost the most ice in the 1985 eruption, and therefore reach only up to deep. The deep ice covering the summit plateau may hide a caldera. Five domes ringing the summit plateau have emerged as the ice has retreated.