Recent studies of Augustine Volcano, funded by other sources, have shown that there are two distinct types of observable electrical activity associated with eruptions. One is a newly discovered continuous radio frequency (RF) radiation at the crater mouth during the main eruption, and the other is large-scale lightning in the volcanic plume several minutes after the main eruption, with characteristics similar to lightning found in thunderstorms. These observations, made using Lightning Mapping Array (LMA) instrumentation developed at the New Mexico Institute of Mining and Technology, were the first detailed, high time resolution observations of such volcanic electrical activity. In this new research program volcano-produced electrical activity will be observed at two permanent sites in Alaska with an array of atmospheric electrical instrumentation including the LMA to make detailed three-dimensional images of the electrical activity; and electric field mills, fast antennas and slow antennas to characterize the polarity of the lightning activity. A low-power version of the LMA sensor will be developed, which will allow for long-term monitoring of volcanic electrical activity in remote locations, and for rapid deployment to sites with no grid power available. The research will involve both scientific studies of volcanic lightning and electrical activity, and continued development and advancement of the instrumentation for making such observations. The intellectual merit of the proposed research will derive from the scientific investigations. One major scientific goal is to use lightning mapping observations to ascertain the electrical structure of volcanic plume clouds. This will help lead to a better understanding of the charging mechanism in the plume. A second major goal is to better characterize the continuous RF activity during the explosive phase. A third major goal is to ascertain the usefulness of monitoring of electrical activity as an additional tool for the determination of the status of active volcanoes.
Broader impacts of the proposed activity will include further development of the lightning mapping technique as a useful technology to study and monitor volcanic eruptions. The system that will be developed could evolve into one that could be used to monitor a volcano and confirm eruptions, even when weather conditions preclude visual observations. It could be used as an additional tool to help volcanologists in their decision-making process for generating warnings to nearby populations, and to aircraft. Tracking of the in-plume lightning can give the direction that the ash cloud is moving. The system will give the volcanologists another tool to study the eruptions with high time resolution. The understanding of charging in the volcanic plume could lead to a better understanding of the charging in thunderstorms. A final aspect of the proposed research will be the development of a set of lightweight, solar-powered, battery-operated mapping stations that can be readily deployed for a variety of experiments and studies that are as yet not easily conducted. The involvement of graduate and undergraduate students both in the scientific and applied aspects of the research has broad implications for their education that can only come from working on real problems. This research will involve a collaboration between atmospheric and earth scientists in a cross-disciplinary environment. Inter-agency and international collaborations will be established as needed to work with groups in areas where it looks reasonable to deploy our instrumentation to study active volcanoes. This interdisciplinary activity has already introduced new techniques that will be used for monitoring active volcanoes in Alaska. The collaborations will become broader as interactions develop with volcanologists and disaster planners in communities near volcanoes around the world.
We investigated the occurrence of volcanic lightning at erupting volcanoes. Lightning has been observed at 154 volcanoes in association with 394 eruptions of various sizes and types. This suggests that lightning is quite common and is a general feature of the eruption process. The percent of eruptions with lightning increases as the size of the eruption increases. New instrumental data obtained in this project come from four volcanoes: Pavlof, Alaska, in 2007; Chaiten, Chile, 2008; Redoubt, Alaska, in 2009; and Eyjafjalljokull, Iceland in 2010. The instrumental data suggest that there are two dominant types of electrical activity. The first is a continuous electrical signal (consisting of many small flashes) right at or above the vent during the ejection of ash and gases. The second is lightning that occurs in the plume as it rises into the atmosphere. The lightning flashes in the plume are stronger and longer individual flashes. Lightning is especially vigorous when the plume is >10 km high, and this indicates that the formation of ice plays an important role in volcanic lightning just as it does for ordinary thunderstorms. Lightning occurrence is now being monitored at volcanoes in the North Pacific region using data from the World Wide Lightning Location Network (WWLLN) as a cooperative experiment. The occurrence of lightning is now also being used by volcano observatories as an additional indicator of the occurrence and vigor of eruptions.
