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The MultiGAS station at Poas is operated by OVSICORI and was in place prior to the AVERT partnership. It draws ambient air through a set of electrochemical and infrared sensors, each tuned to detect a specific volcanic gas species (typically H₂O, CO₂, and SO₂).
The unit contains multiple sensors for simultaneous measurement of gas species. Electrochemical sensors detect SO₂ and H₂S, while an NDIR sensor measures CO₂. An additional sensor measures H₂O.
The MultiGAS station is located near the active crater at Poas, where it samples the gas plume. It provides continuous ratios such as CO₂/SO₂, which are diagnostic of magmatic vs. hydrothermal gas sources. This station is operated and maintained by OVSICORI.
Data are managed by OVSICORI as part of their monitoring network. The MultiGAS record complements the AVERT-contributed seismic, GNSS, magnetic, and soil CO₂ data at Poas.
MultiGAS is distinct from the scanning DOAS and soil CO₂ instruments also used in the AVERT network. Scanning DOAS measures SO₂ remotely via UV absorption, while soil CO₂ probes measure diffuse degassing through the ground. These are documented under their own data type pages.