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Arenal Volcano - John Seach
Costa Rica
10.463 N, 84.703 W
summit elevation 1657 m
Stratovolcano
Arenal is the youngest stratovolcano in Costa Rica and one of its most active. Arenal's most recent eruptive period began with a major explosive eruption in 1968. The eruption of Arenal volcano on July 29–31, 1968, after centuries of dormancy, produced three new fissural craters. The lateral explosion resulted in 78 deaths and damage to former Pueblo Nuevo and Tabacón villages.
Volcanic activity since 1968 has included explosive activity, strombolian eruptions, slow blocky lava flows, lava avalanches, pyroclastic flows, and hyper-concentrated
stream-flows. These present a hazard to tourists and locals near the volcano.
Stage 1 eruptions from 1968–1971 were from a closed system. Stage 2 eruptions from 1971–current were produced from an open system.
Arenal’s crater contains a lava pool, which is composed of viscous basaltic andesite. The lava is extrudes in a pulsating pattern, forms a crust, and then overflows the crater rim and flows almost continuously down the north to southwest
flanks of the volcano.
Degassing occurs in rhythmic pulses along the edge of the pool. Pacaya entered a Strombolian phase in 1984. Pyroclastic flows are common at Arenal volcano. Pyroclastic flows since 1986 have been associated with moderate column collapse from Strombolian explosions, and small block avalanches from active lava fronts.
During the night of 28 August 1993 a previously unknown type of pyroclastic
flow, generated during a partial cone collapse and outpouring of an active lava pool at Arenal. This type of event has subsequently been identified at Arenal in June 1975, May 1998, August 2000, March 2001, at Cotopaxi (Ecuador) in 1877, and at Asama (Japan) in 1783. This phenomenon has important volcanic hazard implications for tourist development on the flanks of the volcano.
Arenal Volcano Eruptions
1968-2008