The ash eruptions subsided when spring rains re-established the lake, Rymer said, but she believes the volcano may erupt again as the lake is depleted during the coming dry season. Eruption of Costa Rica's Poas volcano in April and May was preceded by two years of increasing gravity, thought to result from the intrusion of subsurface magma into the volcanic cone. After Poas's last eruption in 1953, lake depth stayed the same until 1983 when it began decreasing as heating magma caused water to evaporate. The researchers found that a similar process is occurring on the island of San Salvador, which lies about 50 miles (80 kilometers) off the coast of Nicaragua. Eruptions subsided when rains refilled the lake. Guatemala's Pacayo volcano, which erupted 10 years ago, has a different gravity change pattern.
Eruption of Costa Rica's Poas volcano in April and May was preceded by two years of increasing gravity, thought to result from the intrusion of subsurface magma into the volcanic cone. After Poas's last eruption in 1953, lake depth stayed the same until 1983 when it began decreasing as heating magma caused water to evaporate. The researchers found that a similar process is occurring on the island of San Salvador, which lies about 50 miles (80 kilometers) off the coast of Nicaragua. Eruptions subsided when rains refilled the lake. Guatemala's Pacayo volcano, which erupted 10 years ago, has a different gravity change pattern.