Seismic Imaging of Active and Ancient CO2 Pathways in the Little Grand Wash Fault
Session: Critical Zone, Environmental and Cryospheric Seismology [Poster]
Type: Poster
Date: 4/22/2021
Presentation Time: 03:45 PM Pacific
Description:
Understanding the migration behavior of carbon dioxide during long-term geological storage is crucial to the success of carbon capture and sequestration technology as an effective strategy to diminish the effects of anthropogenic climate change. We explore p-wave and s-wave seismic properties across the Little Grand Wash fault in east-central Utah, a natural CO2 seep and analogue for a long-failed sequestration site. Travertines dated to at least 113,000 k.y. and geochemical surveys confirm CO2 leakage. Outgassing is focused in damage zones where the total fluid pressure reduces the minimum horizontal effective stress; regional stress changes may be responsible for decadal- to millennial-scale changes in CO2 pathways. We identify subsurface structure in the upper few hundred meters and define surface CO2 outgassing zones via seismic reflection and first arrival tomography. We tie our results to borehole logs, geology from outcrops, and geochemical data. Our seismic imaging results constrain the fault architecture of both active and ancient outgassing within the system. We present velocity tomograms of the fault zone and construct rock physics models from our hammer seismic data. First arrival tomography results and diffraction analysis suggest a ~100 m wide fault zone is mostly responsible for the CO2 delivery to the surface. Reflection results show that this low velocity zone lies above a broad anticline. We identify low seismic velocities along 4 of 5 seismic profiles that are consistent with unconsolidated saturated sediments within the fault. In contrast, low CO2 flux regions outside the fault zone and at higher elevations show seismic velocities consistent with unsaturated host rock. Anomalously high seismic velocities along the fault are consistent with fault sealing. Studying the behavior of CO2 in this system can give insight of potential risks in future sequestration projects.
Presenting Author: Jonathan Yelton
Student Presenter: Yes
Authors
Jonathan Yelton Presenting Author Corresponding Author jonyelton@u.boisestate.edu Boise State University |
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Seismic Imaging of Active and Ancient CO2 Pathways in the Little Grand Wash Fault
Category
Environmental and Cryospheric Seismology: Deriving Insights from Ice, Avalanches and Beyond