> ## Documentation Index
> Fetch the complete documentation index at: https://data.avert.ldeo.columbia.edu/llms.txt
> Use this file to discover all available pages before exploring further.

# Instruments

> MultiGAS instruments at Poas volcano

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).

<AccordionGroup>
  <Accordion title="Sensor Components">
    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.
  </Accordion>

  <Accordion title="Deployment at Poas">
    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.
  </Accordion>

  <Accordion title="Data Flow">
    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.
  </Accordion>
</AccordionGroup>

<Note>
  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.
</Note>