Improvements in the Geochemical Monitoring Network in Tenerife: Multi-Gas and Continuous Dissolved CO2 stations.

Tenerife is the largest island in the Canary archipelago and hosts El Teide volcano, a 3715 m.a.s.l. stratovolcano characterised by low-temperature fumaroles in its summit crater. Since 2016, changes in volcanic activity have been recorded, resulting in the occurrence of several seismic swarms, variations in geochemical parameters, and slight ground deformation since 2023.  

The Instituto Geográfico Nacional (IGN), the Spanish institution responsible for volcano monitoring, has deployed a multiparameter monitoring network in Tenerife comprising seismic, ground deformation and geochemical networks. During 2024 and 2025, two actions were taken to enhance the latter one in order to detect subtle changes in the fumaroles and the aquifer. These changes could serve as early warning signals of a future volcanic eruption.  

Multi-gas stations are typically used to monitor plumes from active volcanoes. However, as there has been a clear increase in the volcanic activity in Tenerife since 2016, we have decided to deploy a Multi-Gas station inside El Teide's crater since September 2024, despite not showing an active plume. This station measures SO2, H2S, CO₂, CO and H2 concentrations in the air at 30 cm above the ground every six hours with a measurement window of 30-minute length at a sampling frequency of 1 Hz. Alongside this, meteorological data is recorded. All data is stored locally and transmitted in near real time to the server. 

Until mid 2025, the dissolved CO₂ concentration was determined by sampling every three months at eight sampling points in Tenerife. To dramatically improve the sampling frequency, three Mini-CO₂ instruments from Pro-Oceanus have been installed at the three most interesting sampling sites. This device uses infrared detection to measure the partial pressure of CO₂ gas dissolved in water. The instrument also measures Total Dissolved Gas Pressure (TDGP), CO₂ concentration, and water temperature. 

At each site, a Mini-CO₂ was installed alongside a meteorological station. Data from the Mini-CO₂ is acquired every 15 minutes, while data from the meteorological station every 10 minutes. All data is stored locally and transmitted in real time to the server. 

In this contribution, the first records and results from both improvements in the geochemical monitoring network in Tenerife are shown.