Global Volcanism Program | Image GVP-07074
The rim of Active Crater is highest on the SW side and drops rapidly on the NW side. The 700-m-wide crater contains an acidic lake that is periodically partially ejected by explosive eruptions and therefore varies in depth. Trade winds from the ENE distribute acid fumarolic plumes from the Active Crater to the SW, destroying vegetation. Water geochemistry studies indicate that the crater lake water is leaking through the edifice into the north flank drainages.
Photo by Guillermo Alvarado (Instituto Costarricense de Electricidad).