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. 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.