Heavy cloud formations have prevented satellite observations. The main cone is heavily vegetated with the exception of three craters to the west. A lake covered the crater floor. The most recent confirmed eruption of Rincon de la Vieja was in early 1992. Rincon de la Vieja has erupted at least 16 times since 1851.
Most eruptions are phreatic and include the emission of gas and ash.
Lahars are often generated by displacement of the crater lake. Steve Mattox Click here for more information about Costa Rican volcanoes.