The phrase "active vent" is correct and usable in written English.
It can be used in contexts related to geology, volcanology, or engineering, referring to an opening through which gases or liquids can escape.
Example: "The researchers observed the active vent of the volcano, noting the continuous release of steam and ash."
Alternatives: "open vent" or "functioning vent".
During the fall of 2014, the summit lake practically disappeared and the crater was substantially occupied by an active vent with moderate to sustained Strombolian activity (such as the eruption of November 27, 2014).
Halema'uma'u Crater, located within Kilauea's caldera, is the volcano's most active vent.
…recent lava flows, contains the Halema'uma'u ("Fern House") Crater, an inner crater that is Kilauea's most active vent.
The floor, paved with recent lava flows, contains the Halema'uma'u ("Fern House") Crater, an inner crater that is Kilauea's most active vent.
Comtet, T. et al. Molecular and morphological identification of settlement-stage vent mussel larvae, Bathymodiolus azoricus (Bivalvia: Mytilidae), preserved in situ at active vent fields on the Mid-Atlantic Ridge.
Examination of the surface elevations of Ray Lava Lake, Werner Vent and Active Vent indicates that the active vents were more or less in magmastatic equilibrium in 2001 December.
A further increase in the activity will cause the transition to Strombolian activity with the ejection of juvenile materials from active vents.
Noah and Laura Dawn own a retreat centre about three miles downhill from the most active vents.
In November 2000 the first system was deployed at Pu'u 'O'o (Kilauea, Hawai'i) to target persistently active vents.
Feely, R. A. et al. Composition and dissolution of black smoker particulates from active vents on the Juan de Fuca Ridge.
"Active venting of lava and hazardous fumes continue in Leilani Estates," the civil defense agency said Monday, noting that residents of the evacuated subdivision will be allowed to check on their properties during the day.
