Arenal
Costa Rica
10.463°N, 84.703°W; summit elev. 1,657 m

The conical Volcano (see fig.1 below) Arenal is the youngest stratovolcano in Costa Rica and one of its most active. The 1657 meter-high andesitic volcano towers above the eastern shores of Lake Arenal, which has been enlarged by a hydroelectric project. Arenal was constructed to the NW of the older Chato volcano, which contains a 500 meter-wide summit crater. The activity of Chato ended about 3500 years ago, and the oldest known Arenal rocks are only 2900 years old. Growth of Arenal has been characterized by periodic major explosive eruptions at several-hundred-year intervals and periods of lava effusion that armor the cone. Arenal's most recent eruptive period began with a major explosive eruption in 1968. Continuous explosive activity accompanied by slow lava effusion and the occasional emission of pyroclastic flows has occurred since then from vents at the summit and on the upper western flank.

Arenal was a dormant stratovolcano. Its 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. The volcano lies directly adjacent to Lake Arenal, a dammed reservoir for generating hydroelectric power. The volcano has been watched by many tourists from a mountain lodge 2.8 km S of the vent that enables visitors to hear, to see, and occasionally to smell its dynamism. The town of La Fortuna is located 7 km NE of the volcano. The Arenal Observatory is 2.7 km S of the summit.

Information summarized from: http://www.volcano.si.edu/gvp/world/region14/costaric/arenal/var.htm General References: Alvarado, G.E., Barquero, R., Soto, G., and Hidalgo, G., 1988, Referencias bibliográficas principales sobre el Volcán Arenal y áreas vecinas: Boletín del Observatorio Vulcanológico del Arenal, v. 1, no. 2, p. 57-67

Conical volcano Fig. 1