Global Volcanism Program | Image GVP-10174
The forested island at the right is Cerro Grande (Isla la Cabra), a post-caldera lava dome on the SW side of Coatepeque caldera. The partially submerged 916-m-high rhyodacitic dome has a basal diameter of about 2.5 km and a volume of about 0.5 cu km. Small San Pedro Island (left center) is exposed during low lake levels. A fissure here reportedly erupted cinders in 1902. However, warm springs issue from the adjacent lake shore, and this event was considered by Sapper (1917) to more likely represent expulsion of water and suspended sulfur.
Photo by Lee Siebert, 2002 (Smithsonian Institution).