By monitoring the changes in chemistry and temperature of water and steam at a volcano over time, scientists can obtain useful information about changes in volcanic activity. These volcanic hydrothermal systems contain elemental components that signal the presence of magma, such as magmatic carbon dioxide or high helium-isotope ratios (3He/4He). Hydrothermal monitoring sites at Cascades volcanoes include instruments that measure water pressure (to calculate flow rate), chemistry, temperature, and conductivity (to calculate quantities such as heat flow). Scientists visit these sites regularly to take samples of liquid and gas and measure the rate of water flow. The results from these measurements tell researchers whether hydrothermal activity is changing, and can indicate the presence or absence of fresh magma.
There are three hydrothermal monitoring sites at Mount Baker.
In 1975, there was a significant increase in heat and gas output from fumaroles in Sherman Crater at Mount Baker. This change in activity resulted in regular hydrothermal monitoring at the volcano. Gas samples have been taken every year, and in 2012 temperature monitors were installed that measure the ground temperature at the Sherman Crater fumarole site. The sensors take measurements every hour, and the data is downloaded once a year during the summer field season. The first hourly temperature data from Sherman Crater will be downloaded in July 2013. This new bank of continuous data will provide a baseline of hydrothermal data that will provide useful information and help scientists to determine a change in the level of volcanic activity, potentially signaling unrest.
After the increase in hydrothermal activity was observed at Sherman Crater in 1975, more hydrothermal monitoring was done at other places in the area, including Boulder Creek, which receives outflow from Sherman Crater. Water samples and discharge measurements were taken frequently (every few months) in the 1970s. Simultaneous measurements of water chemistry and discharge allow scientists to estimate the outflow of certain hydrothermal, and potentially magmatic, components from Sherman Crater.
The Boulder Creek site started to be regularly monitored again in 2009. Since then water chemistry and discharge measurements have continued to be made intermittently, in order to define baseline conditions in Boulder Creek in advance of future unrest in Sherman Crater.
Unnamed Tributary to Sulphur Creek
This stream was discovered to contain high chloride and magmatic carbon, which are indicators of volcanic gas. A pressure-temperature-conductivity monitor was installed at the site in 2008 to record data hourly. The site was visited every year from 2008-2012 to download the data, take water samples, and make onsite water flow-rate measurements. In 2012 the monitor was removed because it was determined that the 2008-2012 data provide an adequate baseline for comparison with intermittent measurements. Water samples and discharge measurements are still being collected at regular intervals, though not continually, at this site. In the event of volcanic unrest, monitors could be deployed again, and the resulting data could be compared to the baseline of continuous data collected in 2008-2012.