Detection of volcanic plumes, especially ash-laden ones, is important both for public health and aircraft safety. A variety of geophysical tools and satellite data are used to monitor volcanic eruptions and to predict the movement of ash. However, satellite-based methods are restricted by time of day and weather, while radars are often unavailable because of cost and portability. We have proposed to detect volcanic plumes using GPS signal strength (or signal to noise ratio, SNR) data. A proof of concept study (Larson et al., 2013) showed that multiple eruptions of Mt. Redoubt volcano in 2009 could be detected this way. The figures below provide information on this new technique. The observations are shown on the left – SNR recordings for five consecutive days. The SNR data are repeatable, except during the eruption on day of year 85. The cartoon to the right shows the geometry associated with the observations. Satellite 21 transmitted a signal received by station RVBM. On day of year 85, that signal was disrupted by a volcanic plume.
The GPS receivers used to study the Mt Redoubt eruptions are fairly expensive instruments. They also have the disadvantage that often there are not very many operating near a volcano. To increase the likelihood of detecting a volcanic plume, we need to have more GPS (and GNSS) receivers around the volcano. Instead of geodetic receivers, we have proposed to use cheaper instruments specifically to detect plumes. Shown below are potential plume detections for a notional array surrounding Mt Etna.
See Larson, K.M., A New Way to Detect Volcanic Plumes, Geophys. Res. Lett.,Vol. 40(11),2657-2660, doi:10.1002/grl.50556, 2013. This work is funded by NSF EAR 1360810 and NASA NNX14AQ14G.