The most recent eruption, in 1952, formed a small lava dome on the island's coast.

It was also erupted off the face of an advancing lava dome.

Before the current eruption, it was mostly filled by a rhyolite obsidian lava dome that reached a height of 962m ft, partly devoid of vegetation.

These are typically produced by lava dome collapse or collapse of the eruption column.

Two small lakes occupied the caldera floor on the west and north sides of the lava dome.