The multiparameter station at Galeras Volcano (Colombia): concept and realization

Volcanoes are complex systems, in which the interaction of many different physical and chemical factors and processes contribute to changes in activity. In the past 40 years, our ability to observe and quantify short-term changes in a volcano’s activity has improved due to the installation of seismometers and tiltmeters and the continuous records they provide. However, due to instrumental limitations, the observations have mainly been used phenomenologically, to draw inferences about possible changes on the basis of previous experience. Since 1995, the Bundesanstalt für Geowissenschaften und Rohstoffe (BGR) and the Instituto de Investigación e Información Geocientı́fica, Minero-Ambiental y Nuclear (INGEOMINAS) have been working to develop and deploy a multiparameter (MP) station on Galeras Volcano, Colombia. This station is designed to concurrently measure various geophysical and geochemical parameters. It includes three broadband seismometers at the crater rim, as well as a more remotely located, broadband seismic reference. At other locations in the crater or on the rim, electromagnetic probes, an infrasound sensor and a weather station are operating. The data from these sensors are digitized at each site with 24-bit digitizers and transmitted by spread-spectrum radio, via repeater when necessary, to the Observatorio Vulcanológico y Sismológico (OVP) in the city of Pasto. There they are received and displayed on a networked personal computer and recorded continuously. The data flow into the routine analysis procedures of the OVP and the continuous data are archived on CD. In addition to the other sensors, a system of specially developed sensors continuously monitors the chemistry and physics of the gases at fumaroles on the active cone. The data from this system are also transmitted in realtime to OVP and recorded. The continuous recordings of the MP station are supplemented by regular thermographic measurements of the surface temperature in the crater using an infrared camera. Joint analysis and interpretation of the data streams from the many sensors of the MP station will improve our understanding of the physical processes occurring in Galeras Volcano.