Powerful phreatic eruption at Rincon de la Vieja, Costa Rica

A powerful phreatic eruption took place at Rincon de la Vieja volcano, Costa Rica at 11:40 UTC (05:40 LT) on June 28, 2021.

The event lasted about 3 minutes, ejecting dense column of gas and steam, with some amount of ash, up to 4.2 km (14 000 feet) above sea level, drifting N-NW.

"It was a pretty energetic eruption," said Maarten de Moor, a specialist at the Volcanological and Seismological Observatory of Costa Rica (OVSICORI-UNA).

Ash was deposited on nearby communities, but the eruption did not cause damage or injuries.

Lahars were observed in the volcano's northern drainages.

The National Commission for Risk Prevention and Emergency Management said it had deployed a team to evaluate the situation, and urged people not to approach the site.

The last eruptive phase of this volcano lasted from January 30 to November 3, 2020 (VEI 2).

Geological summary

Rincón de la Vieja, the largest volcano in NW Costa Rica, is a remote volcanic complex in the Guanacaste Range. The volcano consists of an elongated, arcuate NW-SE-trending ridge that was constructed within the 15-km-wide (9.3 miles) early Pleistocene Guachipelín caldera, whose rim is exposed on the south side.

Sometimes known as the "Colossus of Guanacaste," it has an estimated volume of 130 km³ (31 mi³) and contains at least nine major eruptive centers.

Activity has migrated to the SE, where the youngest-looking craters are located. The twin cone of 1 916 m (6 300 feet) high Santa María volcano, the highest peak of the complex, is located at the eastern end of a smaller, 5 km (3.1 miles) wide caldera and has a 500 m (1 640 feet) wide crater.

A plinian eruption producing the 0.25 km³ (0.05 mi³) Río Blanca tephra about 3 500 years ago was the last major magmatic eruption. All subsequent eruptions, including numerous historical eruptions possibly dating back to the 16^th century, have been from the prominent active crater containing a 500 m (1 640 feet) wide acid lake located ENE of Von Seebach crater.

This volcano is located within the Area de Conservación Guanacaste, a UNESCO World Heritage property. (GVP)

Featured image credit: OVSICORI-UNA