On April 23, 2025, the National Commission for Risk Prevention and Emergency Response (CNE) declared a red alert for the Poás Volcano National Park due to a sustained increase in volcanic activity that has been recorded since the beginning of the year. This measure was supported by technical reports from the Technical Advisory Committee on Volcanology and Seismology, composed of OVSICORI-UNA, the National Seismological Network (RSN) of ICE-UCR, and the Atmospheric Chemistry Laboratory of UNA (LAQAT), in coordination with SINAC-MINAE.
Since March 23, 2025, specialists have observed a transition of the volcano toward a more active eruptive phase. The eruptions have been particularly energetic, reaching heights of up to 4,500 meters above the crater. These explosions have been accompanied by intense emissions of ash, volcanic gases, and ballistic projections of rock material. In addition, monitoring systems have recorded significant seismic activity, ground deformation, and other signs consistent with a volcano in an eruptive process.
The CNE has defined different alert levels based on location and risk exposure. A red alert was declared exclusively for the Poás Volcano National Park, which implies a suspension of activities within the protected area. At the same time, an orange alert was issued for the cantons of Grecia and Sarchí, where reports have been made of ashfall and the smell of volcanic gases in urban and rural areas. Finally, a yellow alert was established for the cantons of Alajuela, Poás, Naranjo, Río Cuarto, and Zarcero, where active monitoring continues due to the possibility of indirect impacts.
The effects of the volcanic activity have manifested in various areas. Inside the national park, the accumulation of ash has covered the main lookout, the visitor center, and the terraces located to the north and west of the crater. In more distant areas, there have been reports of sulfur odors and light ashfall. Damage has also been detected in pastures, crops, and livestock areas in nearby communities.
One of the most significant risks identified by experts is the possible generation of lahars, that is, mudflows loaded with volcanic ash, in the event of heavy rains at the summit of the volcano. A significant accumulation of volcanic material has been identified to the west of the crater, mainly at the headwaters of the Desagüe, Anonos, Gorrión, and Agrio rivers. These conditions could favor the sudden mobilization of sediments toward the lower parts of the watersheds.
In this scenario, the CNE has instructed local authorities and emergency committees to increase monitoring and safety measures. It is also recommended to maintain constant communication between institutions and communities, and to use only official sources for updated information. Nearby populations should remain attentive to technical reports and avoid entering unauthorized areas.
This new episode of Poás Volcano confirms the dynamic nature of Costa Rica’s volcanic system and the importance of risk management in a country whose geography is shaped by active geological forces. Volcanic activity, while representing a risk to communities and ecosystems, is an integral part of the country’s natural environment and requires constant monitoring, as well as proper planning in terms of civil protection and environmental conservation.
