Graphs showing a Material of Interest (MOI) classification overlay on a thermal profile of pumice rafts in two different locations. Red indicates a high concentration of pumice while black indicates the absence of pumice. The pumice raft in Argentina shows a negative temperature anomaly where the pumice is cooler than the surrounding water, whereas the raft in Tonga shows a positive temperature anomaly where the pumice is warmer than the surrounding water. The NASA and USGS Landsat 7 images show the location of the cross sections that were used to measure the temperature.
Authors: Paula Chojnacki, William Lyddane, Jason McGilloway, Quinten Geddes, Lindsay Honaker, Conor Coady, Josh Scott
Advisors/Science Mentors: Dr. Kenton Ross, Jamie Favors
Abstract: Pumice is a highly porous volcanic rock that can be formed by both submarine and subaerial explosive eruptions. One of its most significant features is its ability to float in water, since its density often falls below 1 g/cm3. Pumice can accumulate in the ocean into rafts that are tens of kilometers wide and several feet deep. Pumice rafts are frequently formed near isolated islands in the Pacific Ocean, such as the islands in Tonga and Papua New Guinea, but have also formed in many other locations including Chile, Yemen, Alaska, and Mexico. Here, we use MODIS data and Landsat 5 and 7 images to find the spectral signature of pumice and the bands that can be used to detect it. In addition, we create a database listing known pumice raft occurrences. The database includes the date of the beginning of the eruption, the name of the volcano and its latitude and longitude, and the satellites and spectral bands that can be used to identify the raft. This information can be used to detect and track pumice rafts. Our project also creates the foundation for automated pumice raft tracking software. The automated system is based on multiple algorithms that have been developed to detect and monitor volcanic hotspots throughout the globe. The information we have collected will be transferred to our partners so that in the future, pumice rafts can be more easily detected and studied. We hope that the information we have compiled will eventually result in a more timely warning system to divert maritime vessels from affected areas.
Video transcript available here.