Last Friday night, a vapor release at least 300 meters high at the Poás Volcano, in the northwestern province of Alajuela, deposited a large quantity of ashes and rocks in the southeastern sector of the volcano’s crater.
National Seismological Network (RSN) experts on Monday visited the crater to collect water samples from the volcano’s lagoon and sulfur and sludge from inside the crater’s lake.
Earlier this month, National Emergency Commission (CNE) officials urged caution for tourists visiting volcanoes, especially during Easter Holy Week, as five Costa Rican volcanoes are currently in various states of activity.
According to the CNE, the active volcanoes are Rincón de la Vieja and Arenal (in the northwestern province of Guanacaste), Irazú and Turrialba (in Cartago province, east of San José) and Poás.
Poás’ activity last Friday is what experts from the RSN call a phreatic eruption, also known as a phreatic explosion or ultra-vulcanian eruption, which occurs when magma heats ground or surface water. The extreme temperature of the magma results in an explosion of steam, water, ash, rock and volcanic bubbles.
Turrialba earthquake not related
On Tuesday, a magnitude-3.2 earthquake near the Turrialba Volcano shook the area at 12:40 p.m., but RSN seismologist Leopold Linkimer said it was not a volcanic event. The expert said the quake was due to movement along local fault lines at Agua Caliente and Navarro, east of Cartago.
According to the RSN, the quake was located 4 kilometers northeast of Turrialba, near the volcano.