Global Volcanism Program | Image GVP-06227
Furnas volcano, at the eastern end of Sao Miguel Island, contains at least two calderas. The younger 6-km-wide caldera is seen here from its northern rim. At least 11 trachytic pumice layers, all erupted during the past 5000 years, post-date the caldera. A zone of late-Pleistocene to Holocene basaltic-to-trachytic cinder cones and lava domes is located between Furnas and neighboring Agua de Pau volcano. The only historical eruption of Furnas volcano, during 1630, was one of the largest Holocene eruptions in the Azores.
Photo by Rick Wunderman, 1997 (Smithsonian Institution).