Current Projects
Understanding Sulfur Behavior in the Volcanic Critical Zone: Implications for Volcanic Gas Monitoring
Collaborative with Maarten de Moor (GNS Science, New Zealand); Jamie Barnes (Ut Austin) and Shuo Ding (University of Florida)
Some recent volcanic eruptions have caused great harm including deaths (e.g., White Island volcano, New Zealand). These events show that volcanoes are not understood well enough to accurately predict eruptions. Sulfur is one of the most abundant elements in volcanic gases.
Dramatic variations in volcanic gas ratios linked to volcanic activities have been observed at hydrothermal-magmatic systems. However, the specific processes driving these variations at volcanoes prone to explosive eruptions are poorly understood. Of particular interest is sulfur, which occurs in gas, dissolved, and solid forms. This research will investigate the dynamic behavior of sulfur in the volcanic “critical zone”, which is defined as the heterogeneous hydrothermal-volcanic environment between magma and surface. Complex multi-phase interactions in this “critical zone” determine the compositions and fluxes of gas emissions, modulate eruptive activity, provide favorable redox conditions for microbes, and sequester sulfur and certain elements in the crust. This project will investigate well-monitored active volcanoes prone to explosive eruptions. Combining sulfur stable isotopes, gas compositions and fluxes, melt inclusions, and geochemical modeling, the researchers will: 1) Characterize magmatic degassing into the critical zone; 2) Explore time series variations in sulfur isotopes of volcanic gases to evaluate sulfur reactions and sources in dynamic magmatic-hydrothermal systems; and 3) Constrain rates of sulfur sequestration in the upper crust and the resulting implications of this widespread process on subduction zone volatile budgets and ore deposition. This project will advance our understanding of gas monitoring signals at hydrothermal-magmatic systems prone to dangerous phreatic/phreatomagmatic eruptions, which is crucial for hazard assessment and eruption forecasting.
The Cracking of a Craton: Understanding Volatile Release during Continental Breakup
Collaborative with Peter Barry (WHOI) and Chris Ballentine (Oxford)
The oldest and most stable parts of the Earth’s continents are called cratons. When continents break-up, or rift, these stable crustal areas split apart and allow magma to rise from Earth’s deep interior. This forms new crust. When this happens, reservoirs of economically valuable volatile elements like helium and hydrogen get stuck underneath the craton, forming a reservoir. Geologically important volatiles like carbon dioxide also get stuck, but how and why this happens is not well understood.
This project is a comprehensive study of the volatile gases that are being emitted from gas and water seeps along the flanks of the Tanzanian craton - a region where the stable continental craton is actively being “cracked” by rifting and simultaneously heated by plume-induced volcanism. The overall aims are to understand: 1) the mechanisms by which gases have been produced and stored in stable cratons over >109-year timescales, and 2) how they are liberated and transported to the surface during cratonic breakup. The study primarily focuses on helium (He) and nitrogen (N2) and their isotopic characteristics, which are the main constituents of cratonic gas accumulation, but other noble gases (Ne, Ar, Kr, Xe) and their isotopes, CO2, CH4 (as well as their isotopes) and H2 in seeps will also be measured. Field-and lab-generated gas chemistry results will be used to form an integrated model of gas formation and transport along the flanks of the Tanzania craton. Volatile fluxes will be calculated to understand the extent of gas release when a cratonic region is disrupted by rifting and volcanism. Constraining how volatiles are accumulated and released during steady-state rifting and magmatic conditions will allow characterization of cratonic volatile inventories and fluxes. This information will provide valuable context to researchers studying the effects of gases abruptly released from the stable craton to the atmosphere as well as the formation of economically valuable gas reservoirs of helium and hydrogen.
Impacts of Hydrogen Sulfide Emitted from Volcanic Passive Degassing on Atmospheric Chemistry
Collaborative with Becky Alexander (U of Washington) and Simon Carn (Michigan Tech)
This project will support the development of the first global emissions inventory for volcanic hydrogen sulfide (H2S). By improving estimates of natural sulfur emissions to the atmosphere, the uncertainty in the estimates of the global radiative forcing of anthropogenic sulfate aerosols will be reduced.
We plan to: (1) make an initial inventory of global volcanic H2S emissions based on current carbon dioxide and sulfur dioxide emissions measured during passive degassing; (2) measure H2S emissions from select volcanoes; (3) use these observations along with previous work to construct a global emissions inventory of H2S from passive volcanic degassing; (4) implement the new volcanic H2S emissions inventory into the GEOS-Chem global chemical-transport model; and (5) examine the global chemical and radiative implications of the volcanic source of H2S. This work will partially support two graduate students, one each at the University of New Mexico and the University of Washington.
Sources and quantities of dissolved gases in Lake Kivu, Rwanda
Collaborative with Catherine Meriaux (East African Institute for Fundamental Research, University of Rwanda)
Lake Kivu is located in the East African rift and stores vast amounts of dissolved CO2 and CH4. CO2 and CH4 accumulation could lead to a catastrophic release as has occurred at Lake Nyos, Cameroon in the 1980’s. Prior work on the CO2 and CH4in the lake has concluded that at the present-day accumulation rate, catastrophic eruptions could occur within the next 80-200 years. Lake Kivu is located in the vicinity Niragongo, the most active volcano in Africa and large CO2 emitter. Recent volcanic activity has raised awareness that magma, rising from depth to Niragongo could result in enhanced magmatic CO2release into Lake Kivu and accelerate gas accumulation and the potential for catastrophic release. The purpose of this project is to collaborate with scientists from the University of Rwanda to map the locations of CO2 and CH4 bubbles entering the bottom of the lake using sonar. We sample the water and gases in the lake from various depths. The samples are then analyzed at the UCSB Volatiles Lab for complete gas chemistry (CO2, CH4, H2S, N2, Ar, O2, He, H2) and carbon isotopes of CH4 and CO2. The amount of pumped water and gas collected can be used to estimate the amount and composition of gas currently dissolved at depth to assess the extent of gas saturation and the sources of the gases in the lake.
