The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.
This award will support a twenty-four month research fellowship by Dr. Nicole C. Lautze to work with Dr. Jacopo Taddeucci at the Instituto Nazionale de Geofisica e Volcanologia in Rome, Italy for fifteen months, and with Dr. Bruce Houghton at the University of Hawaii for eight months.
This project aims to provide understanding of the origin, fragmentation, and ejection of basaltic volcanic ash. Fallout of volcanic ash is arguably the most widespread of all natural hazards, having the potential to affect climate, crops, water supply and air travel on international scales. This project incorporates analysis of ash samples from single, observed explosions at Stromboli volcano (Italy), and performance of analogue experiments in Rome?s Experimental Geophysics and Volcanology Laboratory. Textural and chemical data will be gained on ~80 unique ash samples each from an individual explosion collected during fieldwork in 2002, and individual explosion samples collected using a motorized glider in subsequent years. These are among the most ?precise? ash samples ever collected. Comparison of ash in these samples with particles created in controlled-fragmentation experiments provides insight into the origin of ash particles. This project addresses questions such as, a) which are the main processes that generate ash particles during basaltic explosions, and b) to what extent can features of ash particles be used as a proxy for explosion dynamics? Insight into such questions will enable a broader understanding of past and future ash-generating eruptions worldwide.
The Project: This project analyzed the properties of basaltic volcanic ash samples collected in real-time (i.e. during eruption) from the Italian volcanoes of Etna and Stromboli. Our primary contributions were to: 1) apply and test a new analysis technique 2) characterize volcanic ash samples 3) expand a limited quantitative database on volcanic ash, and 4) provide insight into the production/fragmentation of ash at basaltic volcanoes, which is not well understood. Approximately ~40 ash samples were analyzed using a Field Emission Scanning Electron Microscope (FE-SEM) linked to relatively new particle analysis software at the Istituto Nazionale di Geofisica e Volcanologia - Roma. Each sample consisted of 100 to more than 1000 ash particles. Approximately ten of the analyzed samples were from each of the following types of activity: a) fire-fountaining at Etna in 2006, b) typical summit crater activity at Stromboli in 2002, c) a volcanic ‘crisis’ at Stromboli in 2007 (including ash generated at a lava-sea entry, during a parosyxmal event, and during summit crater explosions), and d) relatively high intensity explosions at Stromboli in 2009 (the last collected as part of this project). Using the FE-SEM, high resolution images and quantitative data on the morphoscopy and surface chemistry of individual particles within each sample were obtained (see attached figures). Surface chemistry data was particularly useful in reflecting the relative ‘freshness’ of the ash particles. Of the analyzed morphological parameters, the particle (Heywood) diameter proved the most useful in providing an estimate of the grain size distributions. The parameters of compactness and elongation did not well distinguish among samples, such that further exploration of this analysis technique is warranted. Broader Impacts. Fallout of volcanic ash is arguably the most widespread of all natural hazards, having the potential to affect climate, crops, water supply and air travel on international scales. Greater understanding of the processes of ash production and distribution therefore has potential to benefit society at large. However, largely because of the difficulty in analyzing ash particles due to their small size, there exists a relative paucity of studies on the physical properties of volcanic ash. This project employed a relatively new, partly-automated technique to obtain quantitative data on the surface chemistry and morphoscopy of individual ash particles. The study demonstrated the utility of this relatively simple and rapid technique, and the data obtained provided useful insights into the process of volcanic ash production and subsequent chemical alteration at Stromboli and Etna volcanoes. A minimum of two peer-reviewed publications and seven professional presentations will result from this project. The project also established a firm partnership between volcanologists in the US and Italy. Intellectual Merit. The eruption of basaltic ash is a common occurrence and forms a widespread hazard. However, research regarding the process of fragmentation of ash-sized particles through volcanic processes is virtually non-existent. This project therefore addressed a current deficiency in the field. Additionally, it enabled the development of a robust international collaboration among Principal Investigator Lautze, and Professors Taddeucci and Houghton, and built on their foundation of tephra analyses at Stromboli and Etna volcanoes.
