Santa Ana & Izalco
From the Spanish conquest to now Santa Ana's pattern is 2 to 4 eruptions per century . Most activity at this center came from two recently created parasitic vents, rather than the large central volcano, Santa Ana. San Marcelino erupted in 1722 and created a lava field that occupies the middleground of the top photo on the left panel. The rough lava is the green, shrub filled area behind the powerline. The sugar cane in foreground grows on soft ash. Izalco (lhs) was born in 1770 in the middle of a corn field. For nearly 200 years it was El Faro, the lighthouse of the Pacific. A complex and nearly continuous history of lava flows and strombolian explosions created the small symmetrical cone seen today. Cerro Verde provided a spectacular overlook to the eruptions of Izalco that recurred on intervals of a few minutes to few hours. What better place to build a honeymoon hotel? In the late 50's as hotel building proceeded, the volcano stopped. Continuous activity quit in 1957, although there was a small lava flow in 1966. The beautiful hotel has not had many guests (some grateful volcanologists) but has served as a training center for Turismo.
Pioneering studies of fumarole minerals and volcanic gasses made Izalco the highpoint of many trips to Central America by Dartmouth students in the 1960s and 70s. The climb, about a half an hour, was energizing. Since 1966, Izalco's remarkable fumaroles haved cooled to insignificance. In their heyday, after the 1966 eruption, the fumaroles had temperatures of 400 to 600º C. The gasses vented profusely and were noxious. Minerals, formed on the rocks in the fumaroles' throats, included odd copper-vanadium bronzes, never found in nature before.