The island is volcanic (a stratovolcano) and a weak thermal area exists on the north west coast. The island is only 3.5 km wide with an irregular coastline and ancient lava flows. It is thought that Blup Blup last erupted in the Holocene.
The island is volcanic (a composite volcano) and has a modest thermal zone on its northwest coast. The island measures only 3.5 km in width with an irregular shoreline and old lava beds. It is believed that Blup Blup last erupted during the Holocene epoch.