NASA's Terra satellite captured an image of the new vent, located on the southeastern flank of the Turrialba volcano's West Crater, on Jan. 12, a release from the space agency said.
The Observatorio Vulcanologico y Sismologico de Costa Rica reported the new vent exhibited "a vigorous output of bluish gas at high temperature ... that generated a jet-like sound audible from the visitor lookout."
Turrialba is the eastern-most of Costa Rica's active volcanoes.
The rock at the summit of Turrialba is very weak due to the intense rains of the region and the persistent hydrothermal activity at the summit, seismologists said, allowing new vents to open when pressure from below is high enough to make its way through the weakened rock.
The current eruptions and vent openings are the first substantial activity at Turrialba since the 1860s, researchers said.