The Santa Ana Volcano or Ilamatepec (Spanish: volcán de Santa Ana) is a large cinder cone volcano located in the Santa Ana department of El Salvador. At 2,381 metres above sea level, it is the highest volcano in the country. It is located immediately west of Coatepeque Caldera.
The summit of Santa Ana features four nested calderas and volcanic craters, with the innermost containing a small crater lake. Collapse of the summit during the late Pleistocene (inferring from underlying soil samples, the upper age limit is no more than 57 000 years ago) produced a massive debris avalanche that reached the Pacific Ocean, forming the Acajutla Peninsula. Subsequent eruptions have largely rebuilt the edifice.
There have been numerous historical eruptions since the 16th century, both at the summit and from cinder cones on the lower flanks, and also the flank vents of San Marcelino located east of Santa Ana. The San Marcelino vents erupted in 1722 and flowed eastwards for 11 km, destroying the village of San Juan Tecpan.
In October, 2005, the volcano erupted, killing at least two people, injuring seven people, forcing many people to flee their villages. The volcano spat rocks for over 1.5 km (0.93 mi) with rocks the size of cars. The eruption contributed to the damage from Hurricane Stan. The most recent previous eruption had been in 1904.