Research
"Research is to see what everybody else has seen, and think what nobody has thought" (Albert Szent-Gyorgyi).
Bubbles in magma: Their birth, evolution and death
Magma in volcanic eruptions contains an extra ordinary number of bubbles. The birth (nucleation), evolution (growth and coalescence) and death (escape) of these bubbles play a critical role in the initiation and style of volcanic eruptions. The questions I tend to address include: What is the kinetics of bubble nucleation and growth in eruptions? How bubbles escape from magma en route to the surface?
Hajimirza et al. (JGR 2019), Giachetti et al. (G3 2019), Gardner et al. (Geochim. Cosmochim. 2018)
The figure on the left shows a schematic of bubble nucleation and growth in decompression experiments. I developed a reliable nucleation model by calibrating classical nucleation theory with experimental results.
How fast magma ascends to the surface?
Magma ascent rate from magma reservoir to the surface is arguably the most important parameter that determines whether an eruption is effusive or explosive. Given that direct magma ascent is not directly observable, magma ascent rate must be inferred from eruption products such as vesicles in pyroclasts or melt inclusions.
Hajimirza et al. (Nature Comm. 2021), Barth et al. (JVGR 2019)
The figure on the left shows magma ascent rate estimates for Plinian silicic eruptions. We showed the average decompression rate estimated from bubble number density under heterogeneous nucleation matches estimates from independent geospeedometers.
Magma dynamics in volcanic eruptions
Understanding the dynamics of magma ascent in coherent manner with observations from eruptions is essential for volcano monitoring and risk mitigation. I study magma dynamics including the fluid dynamics of multiphase bubbly flow, the geometry of volcano's subsurface plumbing system and magma fragmentation.
Hajimirza et al. (EarthArxiv2020)
The figure shows the schematic of magma dynamics in Plinian eruptions. My research aims to better understand the interaction between the fluid dynamics of magma ascent, vesiculation and magma fragmentation.
Hydrothermal and phreatomagmatic eruptions
The heat transfer from magma to ground and surface waters drives hazardous phreatomagmatic or spectacular geyser eruptions. I study the thermodynamics of water and steam to better understand the energy balance in phreatomagmatic and geyser eruptions.
Reed et al. (PNAS), Jones et al. (In preparation)
This video by Yellowstone National Park shows Steamboat geyser started erupting again in 2018. In Reed et al. we studied what caused the reawakening of Steamboat, the world's tallest active geyser.