Volcano Live
volcanolive.com
Arenal Volcano - John Seach
Costa Rica
10.463 N, 84.703 W
summit elevation 1720 m
Stratovolcano
Arenal is the youngest stratovolcano in Costa Rica and one of its most active. 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.
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.
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.
1993 Eruption
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.
1968 Eruption
Cows were seen by farmers moving down from the middle upper slopes of the volcano 2 weeks prior to the eruption. A major explosive eruption occurred ar Arenal volcano between July 29–31, 1968, after centuries of dormancy. The eruption produced three new fissural craters. The lateral explosion resulted in 78 deaths and damage to former Pueblo Nuevo and Tabacón villages.
1951-65 Unrest
An increase in restlessness occurred at Arenal volcano beginning 1951. This included emissions on the NE flank of the volcano, decrease in water level of Cedeño lake
on the north flank, causing fish death, fumaroles at the summit crater increased in number: 15 in 1951 and 30 in 1959.
Arenal Volcano Eruptions
1968-2009, 1750 ± 50, 1440?, 1400?, 1030?, 1020?, 750 AD ± 50, 700 AD?, 650 AD ± 100, 550 AD?, 400 AD?, 170 BC ± 200, 270 BC?, 380 BC ± 200, 830 BC ± 500, 1250 BC ± 200, 1450 BC?, 1650 BC?, 1770 BC ± 100, 2250 BC?, 2800 BC?, 3190 BC ± 100, 3350 BC?, 3900 BC?, 4450 BC?, 5060 BC ± 150