Monitoring and Modeling Active Volcanoes Using near-Continuous Fumarole Temperature Measurements

Understanding a volcanic system is critical for reliable forecasting of eruptive activity. By monitoring many different aspects of a volcano's behavior the chance of warning of an impending eruption is maximized, although there are many eruptions that have no recognizable precursors. Measuring fumarole temperatures can be a low-cost addition to an existing monitoring network, and as fumaroles can be distal to the active crater, risk to scientists and instrumentation is minimized. Modeling of these fumarole temperatures can be used to identify changes within the volcanic system and can also help to understand the hydrologic system, which is frequently ignored but can have a strong effect on volcanic activity. We have recorded fumarole temperatures, rainfall, self-potential, seismicity, atmospheric temperature and atmospheric pressure every five minutes at Masaya volcano in Nicaragua since May 2006.

At Masaya we saw fumarole temperatures increase by 3 to 5 °C during activity at the vent 3.5 km away. These temperature increases showed clear evidence of volcanic, meteorologic and hydrologic interaction. They also raise questions about the factors controlling fumarolic activity at Masaya volcano in particular and at active volcanoes in general. We recorded rapid, cyclical variations in the temperature signals at our distal site that correspond to volcanic activity, but with an apparently important link to the atmosphere, as temperature transients often correlated with rainfall events. Current models do not address this level of detail or emphasize the effect of the local groundwater system. Using finite element modeling we have begun to recreate the system at Masaya and have found that permeability, pressure and fumarolic gas interaction with groundwater are important variables. Continued collection and analysis of temperature measurements helps to improve our understanding of volcanic systems, potentially helping in forecasting eruptive activity.