Dynamics of lava dome eruptions

Lava dome eruptions are characterized by the slow extrusion of viscous, crystal-rich magma, resulting in the formation of spines and domes that can persist for months to decades. The eruption behavior is influenced by the equilibrium between volatile exsolution and gas escape through a shallow conduit whose permeability is subject to changes due to vesiculation, crystallization, shear, and brittle fracturing. When pore networks and fractures interconnect, gases are vented, leading to effusion dominance. Conversely, when sealing occurs through compaction or healing, pore pressure increases, and fragmentation triggers ash-rich explosions. Strain is localized into marginal shear zones and faults, which can either create anisotropic pathways or act as barriers, causing rapid transitions between quiet extrusion and bursts. Given that these controls operate near the surface, lava domes are susceptible to changes in ascent rate and degassing efficiency. Therefore, integrated monitoring, encompassing deformation, seismicity, gas, and thermal data, is crucial for anticipating style shifts and mitigating risks. Our research establishes a link between crystal-scale deformation and shear-zone permeability, providing insights into sealing-venting cycles and enhancing the forecast of eruption style shifts.

Pre-eruptive hydrous mineral stability

Amphibole serves as a crucial hydrous phase in intermediate-silicic magmas and acts as a sensitive barometer of pre-eruptive conditions. Its stability is influenced by various factors, including pressure, temperature, melt composition, dissolved volatiles, and redox state. During ascent or heating, amphibole records disequilibrium through resorption and reaction rims of anhydrous phases such as pyroxene, plagioclase, and Fe-Ti oxides. These rims provide insights into shifts in storage depth, thermal input, volatile budget, and oxygen fugacity. Beyond decompression and heating, the volatile system plays a decisive role. Interaction with CO2-rich fluids lowers the activity of water (H2O) and rapidly destabilizes amphibole. Conversely, more oxidizing conditions shift equilibria toward Fe3+-rich assemblages. Since these drivers often act in concert, rim thickness, microlite fabrics, crystallography, and mineral chemistry collectively encode multi-parameter histories. When analyzed in conjunction with melt and volatile data, amphibole textures reconstruct storage, recharge, and redox conditions, crucial inputs to ascent and degassing models. Our research aims to decipher these rims to quantify timescales and volatile-redox shiftsprior to eruption.

Volatile budgets and degassing in Rift Zones

Continental rifts serve as significant sources of deep carbon dioxide (CO2) and other magmatic gases due to the presence of long-lived faults and shallow magmatic-hydrothermal systems that provide efficient pathways to the surface. A substantial portion of the release occurs diffusely through soils, steaming grounds, and fractured terrains, necessitating the use of dense ground flux surveys with isotopic source distribution. Fault architecture plays a crucial role in controlling flux: normal faults and ring fractures concentrate flow into narrow zones, which can accumulate to substantial complex-scale emissions. At depth, melt inclusions reveal that rift magmas, often alkaline to peralkaline, are volatile-rich but are stored shallow and variably undersaturated. The ascent dynamics govern the decoupling of gas and melt. Our research integrates structure-focused flux mapping with petrologic volatile inventories to refine rift-scale volatile budgets and hazard assessment.

Explosive volcanism in the East African Rift

Explosive eruptions in the East African Rift originate from volatile-rich, often peralkaline rhyolite–trachyte magmas stored within intricate caldera systems. Extended repose periods necessitate risk assessment based on tephrostratigraphy supplemented by contemporary monitoring (seismicity, deformation, gas, and thermal data). In the Kenya Rift, clustered caldera systems (Olkaria–Longonot–Suswa–Menengai) exhibit recurring explosive phases interspersed with dome growth and active geothermal systems. In the Ethiopian Rift, peralkaline centers preserve substantial regional tephras that document punctuated explosive periods and recent unrest, underscoring likely common transitions between hydrothermal and magmatic activity. Collectively, studying these systems illustrate how rift architecture and magma composition determine the style, frequency, and extent of explosive volcanism along the rift. Our research primarily establishes tephrostratigraphic frameworks by integrating glass chemistry and dating techniques to enhance source attribution, chronology, eruption style, and hazard assessments.

Magma Rheology and Crystal deformation

Magma is a multiphase fluid whose flow properties undergo significant changes as it cools, crystallizes, and degasses. Factors such as temperature, composition, dissolved volatiles, and the size and shape of crystals and bubbles play a crucial role in determining whether deformation is distributed, localized into shear bands, or culminates in abrupt failure. The growth of crystal frameworks increases resistance to flow, introduces a finite stress to initiate movement, and renders the behavior highly strain-rate and history-dependent. Within these stress fields, crystals deform through dislocation or diffusion creep, kinking, twinning, microfracturing, and dynamic recrystallization. The resulting microstructures, along with preferred crystal and microlite alignments, serve as archives of ascent conditions. We employ high-resolution electron backscatter diffraction (EBSD) to analyze these microstructural archives and couple them with rheological models to establish a link between crystal deformation and evolving viscosity and failure thresholds.

Faulting in volcanic environments

Faulting is prevalent in volcanoes, manifesting in various forms such as conduit walls, dome margins, caldera ring faults, and landslide bases. This faulting can lead to extreme strain localization, intense heating, and transient frictional melts that subsequently quench as pseudotachylytes. Due to the strong nonequilibrium nature of melting, low-temperature phases and interstitial glass are the first to enter the melt, thereby influencing its chemistry. As slip continues, mixing and entrained fragments contribute to the formation of a crystal-bearing suspension. The composition, temperature, and crystal fraction of this suspension determine the viscosity and shear resistance of the melt. Depending on the evolving rheology, a thin melt layer may either lubricate slip or act as a viscous brake. The onset of flash heating, melting, and thermal pressurization, as well as the persistence of melt layers, are influenced by factors such as roughness, porosity, and fluid pressure. Pseudotachylyte glass, microlites, and geochemical signatures serve as archives that provide insights into slip rate, strain localization, and the time-temperature path. Our research focuses on the chemistry and rheology of these melts to decipher slip conditions and dynamic weakening in volcanic faults.