The geologically young and mostly unvegetated cone is primarily constructed of andesite and basalt rock.

Historical eruptions have taken place at the summit crater, and Aeseput, a vent on the volcano's north-east flank, which was formed in 1906.

[4] On 6 January 2015, an eruption began when an explosion caused a partial collapse of a summit lava dome, sending an avalanche down the west flank.

All three times the volcano spewed a massive column of ash more than 6,000 m (19,700 ft) into the sky.

[7][8] The October eruption occurred about a week after a powerful earthquake and tsunami struck the island.