Arenal, Costa Rica

Arenal was a dormant stratovolcano. Young deposits were of the slopes of the volcano but it had not erupted in historic time. Arenal's status changed dramatically in July of 1968. An explosive eruption produced hot avalanches and ejected blocks that devastated the west flank of the volcano and killed 78 people. Arenal has been continuously active since 1968. This photo, taken on May 27, 1992, shows a slow moving lava flow on the west flank of Arenal. Photograph copyrighted and provided by Steve O'Meara of Volcano Watch International.

Strombolian eruptions occur at Arenal at intervals of several minutes to hours. Explosions can send ash plumes more than 1 km above the volcano. Some eruptions generate pyroclastic flows. Photograph copyrighted and provided by Steve O'Meara of Volcano Watch International.

Explosive eruption at Arenal, June 1987. Note large bombs falling from eruption cloud. Photograph by Brandall Suyenobu and Mike Lyvers.

Slow moving block lava flows are also common at Arenal. The flows start fires that destroy forests and crops. Photograph copyrighted and provided by Steve O'Meara of Volcano Watch International.

Night photo of lava flow on the west flank of Arenal. Photograph copyrighted and provided by Steve O'Meara of Volcano Watch International.

Prior to the current eruption, Arenal had not erupted since 1500 A.D. This long interval between eruptions highlights the difficulty in distinguishing extinct and dormant volcanoes.

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Sources of Information:
Global Volcanism Network, 1992, Summary of Recent Activity: Bulletin of Volcanology, v. 55, p. 140-146.

Global Volcanism Network, 1992, Summary of Recent Activity: Bulletin of Volcanology, v. 55, p. 615-617.

McClelland, L., Simkin, T., Summers, M., Nielsen, E., and Stein, T.C., 1989, Global Volcanism 1975-1985: Englewood Cliffs, New Jersey, Prentice Hall, 655 p.

Melson, W,G., and Saenz, R., 1973, Volume, Energy, and Cyclicity of Eruptions at Arenal Volcano, Costa Rica: Bulletin of Volcanology, v. 37, p. 416-437.

Simkin, T., and Siebert, L., 1994, Volcanoes of the World: Geoscience Press, Tucson, Arizona, 349 p.

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