Global Volcanism Program | Image GVP-09310
Ash and mud from a small phreatic explosion rise above the steaming crater lake of Poás volcano on August 28, 1988. Geyser-like phreatic explosions had been occurring since June of the previous year and lasted for a few more months beyond August 1988. Geyser-type activity was almost continuous during the second half of August and the first week of September, with black mud plumes rising 5-10 m. During the rest of the month, plumes rose as much as 25 m. Small mud eruptions continued, and by April 1989 the crater lake disappeared.
Photo by E. Valverde, 1988 (published in Barquero, 1998)