Poas

A geyser-like ejection of steam and ash rises above the surface of the crater lake of Poas volcano in July 1977. The white ring at the base of the eruption column is a steam cloud that is traveling laterally away from the vent along the surface of the crater lake. Mild phreatic explosions such as this one were typical of an eruption that began in May 1977 and lasted at least until July. The crater walls rise about 250 m above the lake.