Deception Island

Deception Island sits in the South Shetland Islands near the Antarctic Peninsula, covering about 79 square kilometers as the exposed, horseshoe-shaped rim of an active shield volcano roughly 30 kilometers across, with a maximum diameter near 15 kilometers; Mount Pond, its highest point, reaches 539 meters. The island is itself a flooded caldera, its center forming the bay of Port Foster, about 10 kilometers long and 7 kilometers wide, reached through a narrow, 500-meter-wide entrance called Neptune's Bellows. Geologists debate how that caldera collapsed, attributing it either to a hydrovolcanic eruption of the Outer Coast Tuff Formation that released about 30 cubic kilometers of magma, or to regional tectonic activity; the surface itself is built from pyroclastic deposits belonging to the pre-caldera Port Foster Group and the post-caldera Mount Pond Group. Historical eruptions occurred in 1839-1842, 1967, 1969 and 1970, and studies indicate several large eruptions have struck the island within roughly the last 10,000 years. This entity documents Deception Island specifically as a geological formation, the flooded caldera rim of an active shield volcano.