Volcanologists from the University of Costa Rica’s National Seismological Network (RSN) reported a new eruption of Turrialba Volcano at 6:58 a.m. on Thursday.
The explosion expelled ash and vapor more than 1 kilometer high above the crater and lasted for about 10 minutes.
RSN volcanologist Mauricio Mora said minutes before the explosion, instruments at various nearby stations recorded a strong tremor around the Turrialba area.
Ash continued to spew from the crater during most of the morning, RSN reported.
Wind direction at the time was heading west and southwest from Turrialba, therefore ashes from the explosion reached communities in the northeastern part of the San José metropolitan area, including Guadalupe, Sabanilla and Coronado.
The National University’s Volcanological and Seismological Observatory of Costa Rica (OVSICORI) said ash was expected to spread throughout a 50 km (31 mile) radius around the volcano, which is located some 50 km east of San José.
Activity at Turrialba Volcano had been muted in recent weeks following a very active period that started after strong explosions on April 30.