The Turrialba volcano erupted for about 25 minutes late Wednesday and spewed ash as far away as Puriscal.
The nation’s emergency network reacted quickly, but the activity has been expected. There has been an alert at the volcano and its national park since 2010, and several communities near the mountain had been evacuated.
The Observatorio Vulcanologico y Sismologico said that ash fell in San Gerardo de Irazú, San Ramón de Tres Ríos, Coronado, Moravia, Curridabat, Desamparados, Aserrí, Escazú, Santa Ana, Belén, Guácima de Alajuela, Río Segundo de Alajuela, San Pedro Montes de Oca, Guadalupe, San José and parts of Heredia. The plume of ash was to the south and southwest.
The Dirección General de Aviación Civil, issued a warning to commercial passenger jets involving an area with a radius of 20 miles of the volcano and to a height of 19,000 feet. The volcano continues to spout a column of gas.
The eruption was between 11:10 and 11:35 p.m. Wednesday, but scientists had been studying the mountain for several days due to rumblings and low-level seismic shocks.
Most of the reports on the volcano have come from the Observatorio at Universidad Nacional. The volcano experts were at the scene, and one participated in a flyover earlier today. The eruption appears to have made internal changes in the volcano crater.
Now the experts are trying to find out if the eruption is a result of gas that has built up or a mass of magma within the mountain. The later could mean a major eruption.