This monogenetic fissure-controlled, dominantly basaltic volcanism, much of which post-dates the roughly 5000-year-old Fogo eruption, cannot be assigned to either volcano and appears related to en-echelon fissures overlying a fracture zone. Thick pumice deposits thought to originate from the "waist" area may have originated from vents or a caldera destroyed and now buried by young basaltic volcanism. The most noteworthy of the young vents is 485-m-high Serra Gorda, SE of Siete Cidades, and the cone that produced a lava delta south of Agua de Paul village. The majority of the inhabitants of Sao Miguel Island occupy both coasts below this volcanic zone. At least 18 eruptions have occurred during the past 2800 years, although the only historical eruption occurred in 1652. The most recent activity has been basaltic, however two more-explosive trachytic eruptions occurred during the past 1100 years.
