Publications

Oscillations in fluid pressure caused by silica precipitation in a fracture by Atsushi Okamoto and Edward Vinis. Nature Communications, 2025. https://doi.org/10.1038/s41467-025-57199-6

Abstract:

Ubiquitous quartz veins within the crust underscore the contribution of silica precipitation to fault sealing and fluid-pressure changes during earthquake cycles. However, quantifying silica precipitation, fluid pressure fluctuations, and earthquake rupture remains challenging. Here, we present the results of hydrothermal flow-through experiments with constant flow rates that show silica precipitation reduces permeability and induces fluid-pressure oscillations in the flow of highly supersaturated fluid. Following an induction period, the difference between inlet and outlet pressures in the experiments increased and oscillated, reaching a peak before abruptly decreasing, while the background pressure difference increased gradually. Such pressure oscillations resulted from the repeated blockage of flow pathways by silica and the failure of locally sealed layers, which produced characteristic quartz textures. The results suggest that the generation and transport of silica particles in fluid, driven by failure events, may induce transient and local variations in fluid pressure, thereby contributing to earthquake rupture.

Oscillations in fluid pressure caused by silica precipitation in a fracture

Another portion of my research focused on the role silica plays in fluid pressure oscillations within the crust and how this can impact seismic events like earthquake hypocenter migrations or aftershocks. Using flow-through apparatuses, we were able to successfully clog granite fractures and with silica precipitation and witness fluid pressure changes via clog-rupture-reseal cycles. This research is currently under review for publication.

2021 University of Oregon Undergraduate Research Symposium

Isotopic Fractionations Produced During Direct Air Capture of Carbon Dioxide

Abstract

The stable isotope composition of carbonate minerals provides a record of the conditions under which those minerals formed. Carbonate travertine constructions precipitated from high-pH (>11) springs exhibit large and peculiar isotopic variations that are not fully understood, limiting the use of travertine as a paleoenvironmental archive. We carry out laboratory experiments that simulate carbonate travertine formation under controlled conditions (temperature, pH, solution composition, and hydrodynamics) to determine what factors govern their isotopic composition.  In our experiments, a CaCl2-K2O solution with no dissolved carbon is brought to high pH by addition of NaOH.  The solution is exposed to a N2-CO2 atmosphere whereupon CO2 diffuses into solution and undergoes a series of reactions that lead to the formation of a CaCO3 crust.  Data on the mineralogy, morphology, and stable isotope composition of the CaCO3 will be presented. Our experiments also present an opportunity to quantify the rates and limitations of CO2 removal from air by travertine formation.