• Radiocarbon Dating Recent Volcanic Activity on Faial Island (Azores)

      Madeira, José; Monge Soares, A. M.; Brum da Silveira, António; Serralheiro, António (Department of Geosciences, The University of Arizona, 1995-01-01)
      Recent fieldwork on the island of Faial (Azores) led to the establishment of a detailed volcanic stratigraphic sequence, which is composed of five main geological formations. One of them, the Caldeira Formation, comprising mainly pumice fall and flow deposits, was judged to be Holocene in age. Organic materials were found preserved in or below some of the pyroclastic deposits from this formation. Wood, charcoal, peat and soil samples were radiocarbon dated, permitting correlation of deposits from different sequences and the establishment of a chronological framework for the Caldeira volcanic activity. These materials yielded ages from ca. 10-1 ka BP. The average dormant interval in the Caldeira pyroclastic activity from 4-1 ka ago is ca. 400 yr, with eruptions approximately every 200-800 yr. This frequency of activity indicates that the Caldeira volcano is an active, dangerous structure that should be closely monitored.