Arenal volcano appears to be shifting to the west about 7 centimeters (2.75 inches) a year. The movement has been documented by sophisticated measurement devices.
The Observatorio Vulcanológico y Sismológico de Costa Rica of the Universidad Nacional is conducting a field survey to study the movement in conjunction with Georgia Tech. The observatory made the announcement as it disclosed the results of measurements made by researchers at the universities of Oxford and Bristol in the United Kingdom.
The British researchers used lasers, satellites, and GPS devices to document the movement.
Marino Protti, a volcano expert with the observatory, said the movement of the mountain is in the direction of Lake
Arenal. The observatory said that this deformation of the flank of the volcano was not likely to be harmful to humans because there were none in the area nearby.
The scientists still are unclear on the reason for the movement, but Protti was quoted in a university release saying that the new volcano formed with an eruption in 1968 sits on an older, perhaps unstable volcano as a base. Gravity might be causing the movement, he suggested. The worse-case scenario, he said, would be a large avalanche of material.
The European scientists used a network of global positioning devices 1,000 meters up the mountain which provided daily information, according to the university. The scientists noted that the movement of the mountain was greater in the rainy season when moisture lubricated the soil. They also used Laser Imaging Detection and Ranging to maintain precise records.