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The main eruption only lasted about one hour, but the explosion produced an ash-and-gas plume that reached a height of about 10 km above the crater, and satellite observations placed the plume at 14 km altitude. Ash fell in towns west of the volcano, including in Naranjos, Nahuizalco, Juayúa, Ahuachapán and La Hachadura. In 5 km downwind direction, the thickness of the ash reached 10 cm.
2 people were reported killed, probably by landslides triggered by heavy rains, in the town of Palo Campana, and 2000 evacuated. 1,400 hectares of crops were damaged by ash, and hot lahars, a flood of boiling mud and water, with large boulders of up the size of automobiles were reported.
Following the eruption of 1 October, small explosions, degassing, and low-to-moderate seismicity occurred at Santa Ana during 5-11 October. Storms on 12 October 2005 caused lahars that traveled E towards Lake Coatepeque. On 22 October, a lahar was reactivated in the Potrero Arriba area, NE of the volcano. During 22-25 October, tremor beneath the volcano increased and declined again in November and December.
No further eruptions took place, but lahars mobilizing loose deposits from the 2005 eruption continued to occur occasionally until 2007.
Fumaroles and hot springs at and near the acid crater lake continue to be active at varying levels.