Detecting developing volcanic unrest

Global positioning system (GPS) records and seismic data are used to detect developing unrest near active volcanoes. Unrest detection thresholds are derived empirically for each monitoring discipline via outlier analysis of historic data from a given volcano. Unrest severity is estimated from the number of simultaneous cross-disciplinary detections. The algorithm is used to track developing unrest within the Yellowstone caldera between 2008 and 2010. Results show numerous instances of anomalous geologic activity throughout the evaluation period, which can be interpreted as precursors to verified magmatic unrest episodes occurring in early 2009 and early 2010.