Observations were made during a flight over the country. A moderate plume rose from a bank of fumaroles on the SE wall of the inner crater, very similar to its appearance in November 1978.

Geological Summary. Santa Ana (also known as Ilamatepec), is a massive, dominantly andesitic-to-trachyandesitic stratovolcano in El Salvador immediately W of Coatepeque Caldera. Collapse during the late Pleistocene produced a voluminous debris avalanche that swept into the Pacific Ocean, forming the Acajutla Peninsula. Reconstruction of the volcano subsequently filled most of the collapse scarp. The broad summit is cut by several crescentic craters, and a series of vents and cones have formed along a 20-km-long fissure system that extends from near the town of Chalchuapa NNW of the volcano to the San Marcelino and Cerro la Olla cinder cones on the SE flank. Small to moderate explosive eruptions from both summit and flank vents have been documented since the 16th century. The San Marcelino cinder cone on the SE flank produced a lava flow in 1722 that traveled 13 km E.

Information Contacts: R. Stoiber, S. Williams, R. Naslund, L. Malinconico, and M. Conrad, Dartmouth College.