Pyroclastic density currents (PDCs) are ground-hugging currents of hot gas and particles that travel at velocities up to 300 m/s. Because of the inherent danger of observing PDCs in real time, we rely on the deposits for insight into the dynamics of these dangerous currents. Our research uses the well-exposed PDC deposits from the May 18, 1980 eruption of Mt St Helens (WA) to explore how PDCs are influenced by surface roughness. The PDCs produced during the eruption flowed through areas of low and high surface roughness. We mapped and sampled deposits from a single PDC proximal, medial, and distal distances from the source, focusing on changes with distance from source and a comparison between deposits in areas of low and high surface roughness. In general the PDC deposits display poor-sorting and are massive in nature, suggesting deposition from a concentrated current with rapid sedimentation. Grain size and componentry data of deposits downstream from preexisting debris avalanche hummock, which provided high surface roughness, contain a threefold-increase in hummock components relative to PDC deposits in areas of low surface roughness. This suggests that high surface roughness promotes the erosive capacity of PDCs. The main driving force for PDCs is their great density relative to the air, thus increasing the density at the base of the current through substrate erosion could potentially increase the run-out distance, thereby increasing the destructive radius. The results from this research substantiate previous research that erosion by PDCs is a common occurrence, but also demonstrate that surface roughness is a primary contributor to the potential for erosion. Future work should explore the consequences of erosion on downstream dynamics. This will impact the ability of hazard mapping models to more accurately determine areas that are at risk for PDC interaction in the vicinity of volcanoes throughout the world.

After the Great Japan Earthquake in 2011, people’s interest in earthquake risks and hazards in the Pacific Northwest (PNW) has increased due to the tectonic similarity between the PNW and Japan. However, a recent study focused on the perception of hazards and risk amongst University of Washington (UW) students indicated deficiencies in knowledge, perception of risk, and preparedness. In contrast, the overall degree of earthquake readiness in Japan is higher than in the PNW due to a strong culture of safety, accurate knowledge, and a high level of risk perception. The higher level of earthquake readiness in Japan indicates effective communication between the scientific community and general public. The objective of this research is to assess the success of earthquake-education programs in Japan, identify missing elements in the PNW’s education programs, and investigate the preferred communication method of people in the PNW. My work compares the earthquake-education programs, resources, style of communication, and cultural differences between Japan and the PNW. My comparisons suggest a combination of school, self, family, and community educations appears to enhance and increase Japanese individuals’ awareness and preparedness. For example, Japanese schools employ standardized guidelines from the Board of Education to maintain highly consistent education programs. Additionally, the active involvement of family and community in Japanese earthquake hazard education motivate individuals to take necessary actions for mitigation activities. In contrast, earthquake-education programs in the PNW are infrequent and lack a standardized source from the government and scientific authority and the education efforts are infrequent. These results indicate the need for more effective earthquake-education and preparedness in the PNW. Future work will be specifically looking into the preferred communication methods between the scientific community and UW students.

The infamous May 18, 1980 eruption of Mount Saint Helens, Washington (USA) produced several episodes of pyroclastic density currents (PDCs) including the initial lateral blast, which traveled nearly 30 km, and later PDCs in the afternoon, which filled in the area up to 8 km north of the volcano. The afternoon PDCs differed from the lateral blast in that they had a higher particle concentration and filled in the topography up to 30 m. While the concentrated portions of the afternoon PDCs followed deep topographic drainages down the volcano, the dilute overriding cloud partially decoupled to develop fully dilute, turbulent PDCs on the flanks. This research focuses on the dilute PDCs, which deposited thin, cross-stratified, and stratified pyroclastic deposits known as proximal bedded deposits. In order to understand the influence of topography on the formation of these dilute currents and the influence of slope on the currents’ transport and depositional mechanisms, we collected samples from recently exposed deposits, analyzed them via grain size measurements, and combined them with data from an unpublished thesis written in 1988 by David Beeson (University of Texas at Arlington). This allows us to assess modes of origin and transport of dilute PDCs. Results show that bedform amplitude and wavelength increase with increasing slope, as does the occurrence of regressive dunes. The relationship between bedform morphology and flow velocity is an important finding since the controls on bedform wavelength and amplitude remains poorly constrained. This finding is further supported by the occurrence of chute and pool features on steeper slopes relative to progressive dunes on shallower slopes. The collected data will be used to validate numerical models that map and quantify the hazards of PDCs, improving both our understanding of PDC dynamics and the hazards associated with them.

Quantum dots (QDs) are the precursor for numerous burgeoning technologies, including more efficient solar panels and high definition LED displays. QDs are small, soluble crystallites of a semiconductor material that have unique qualities since their electrons are confined in all three dimensions in a region of space smaller than the de Broglie wavelength of their electrons. This allows the electrons to occupy spectrally sharp energy levels like an element or a molecule. Their electronic properties can be tuned as a function of their size. In our lab, indium phosphide QDs are prepared under an inert atmosphere of dinitrogen by hot injection of a phosphine precursor into an indium salt and fatty acid solution. Taking aliquots of the reaction mixture at different time intervals during QD growth allows us to chart the rate of particle evolution and provides information about particle size and uniformity. Indium phosphide is a member of the III-V semiconductor class, meaning they are made from elements from column three and column five of the periodic table, and have desirable properties like direct band gaps which allow these materials to efficiently absorb and emit light as well as faster carrier mobility than II-VI quantum dots. The synthesis of III-V QDs has not allowed for size- uniformity or tunability to be achieved because of the uncontrolled reactivity of the precursors, in particular the group V precursors. Our group has recently uncovered an important acid-catalyzed pathway leading to phosphine speciation during indium phosphide QD growth. My project focuses on addressing this issue by incorporating new, more stable precursors and chelating capping agents to better stabilize the reaction products and intermediates, which would be crucial in controlling the formation and therefore the properties of the resulting quantum dots.