NEWS (12/28/2016): I've recently learned that I will have the honor of receiving the 2017 Early Career Award from GSA's Mineralogy Geochemistry Petrology Volcanology division (MGPV). Thanks to Mike Garcia for the nomination and to the MGPV committee and Wendy Bohrson for the surprise announcement.

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Research topics

As a student and researcher, I have focused on diverse aspects of volcanoes. Below are some of the main interests that I have developed throughout the years, in no particular order!
Also, check my page dedicated to Electron Microprobe Analysis, microRaman or other analytical tools I use for research.




photo_pdc
1 - Pyroclastic density currents (PDCs)
PDCs are one of the major causes of destruction and casualties around volcanic areas. These hot, rapidly moving currents form due to unstable conditions either at the eruptive vent, or within the eruptive plume. We investigate the physical processes that are responsible for the production of PDCs during explosive, plinian eruptions. More specifically, we focus on erupted juvenile tephra and other particles (wallrock, crystals) from PDCs and compare them with tephra from fall phases to unravel the reasons for transitions from stable to unstable plumes.

Collaborations: Lucia Gurioli (Clermont-Ferrand), Jacqui Owen (Lancaster)





photo_leucite2 - Magma crystallization

During their storage at depth and ascent towards the surface, magmas often crystallize as a result of cooling or decompression. When hand samples picked up at the surface are examined in detail, determining the history of the crystal 'cargo' is not always straightforward. Our investigations focus on (1) trying to characterize the kinetics of crystallization (both during cooling and decompression) within mafic and more evolved magmas, and (2) deciphering the crystallization path of minerals found in natural samples through texture analysis and comparisons with laboratory experiments.

Current collaborations: Julia Hammer (UH), Ben Welsch (UH), Fidel Costa (EOS), Oleg Melnik (Moscow/Bristol), Caroline Bouvet de Maisonneuve (EOS)



photo_leucite2 - Diffusion in melts and minerals

Chemical constituents forming melts and minerals in magmas diffuse constantly. When changes in pressure, temperature, oxygen fugacity, or chemistry via mixing occur within a given magma, significant chemical departures from thermodynamic equillibrium occur, often resulting in the formation of concentration gradients within or at the contact between phases. Through diffusion, such gradients tend to flatten out with time. These changes in chemical gradients can be measured and modeled to retrieve timescales of magmatic processes.

Current collaborations: Fidel Costa (EOS), Kendra Lynn (UH), Mike Garcia (UH), Julia Hammer (UH), Fiona Couperthwaite (Leeds), Dan Morgan (Leeds), Dave Graham (Oregon State Univ.)





photo_bubbles4 - Magma degassing

Volatiles trapped within the melt phase of a magma (mainly H2O, CO2, SO2, Cl, HF) tend to exsolve to a separate vapor phase during decompression. Exsolution and expansion of volatiles, which can occur at equiilbrium or disequilibrium, exert a strong control on the eruptive style (effusive vs. explosive vs. highly explosive) and their study helps elucidate the behavior of past eruptions and make predictions for future eruptions. We (1) investigate the textures formed by vesiculation and try to understand ascent history, and derive important eruptive parameters such as decompression rates, and (2) try to understand the conditions for equilibrium vs. disequilibrium degassing through series of laboratory decompression experiments.

Current collaborations: Thomas Giachetti (Rice Univ.), Lucia Gurioli, Julia Hammer, Eric Hellebrand (UH), Jessica Larsen (UAF), Hugh Tuffen (Lancaster)





photo_pumice5- Textural analysis

Volcanic rocks display a wide range in textures, containing vesicles sizing from less than a micron to tens of centimeters in numbers that vary from a few per cubic cm to several hundreds of million, and shapes that are often modulated by coalescence and/or deformation processes during magma ascent. Volcanic rocks also contain a variety of crystals with sizes ranging from nanolites (<micron) to large phenocrysts (up to several cm) and can display very different morphologies even within a same species (ex. plagioclase). Quantifying such complex textures is a major challenge that we attempt to deal with using simple cost effective techniques (SEM image acquisition and 2D size and number quantification through computer algorithms).

Current collaborations: Lucia Gurioli, Thomas Giachetti, Helge Gonnermann (Rice Univ.), Jacqui Owen (Lancaster)




photo_avalanche
6 - Edifice collapse and debris avalanches
Aside from pyroclastic density currents, volcanic flank collapses and the generation of debris avalanches (rapidly moving rock mixtures that can travel several tens of kilometers in distance and involve volumes of several cubic kilometers), are a major hazard around volcanoes. We have found that in many cases, these destructive events are not associated with eruptive activity, making them difficult to predict. We focus on the propagation and deformation during transport of such mass movements, and try to determine the causes for flank destabilization in the first place. Combinations of field surveys and analogue models using granular materials are used to investigate these processes.

Main collaborator(s): Ben van Wyk de Vries