Cascadia ocean margin, offshore Washington, USA poses a major seismic and environmental hazard to the population centers of the northwestern United States and western Canada with 10,000-year record of magnitude 9 or greater earthquakes occurring in every 500-year intervals that ruptured the entire Western United States and Vancouver Island. Additionally, within the accretionary prism, the area contains high concentrations of methane hydrates with clear observational records of continuous methane seepage. In the event of a major earthquake, the gas-hydrate stability field is likely to be disturbed, release large quantities of methane into the atmosphere, and cause major impacts to the climate. Here, we apply prestack waveform inversion and reversetime migration to estimate the depth image and visco-elastic model of the methane hydrates and the associated zones at the Cascadia margin. Combining the estimated visco-elastic model with the methane hydrate stability as functions of temperature and pressure, we also estimate the upper and lower bounds of the subsurface temperatures. Furthermore, we also propose a new approach to combine seismic analysis with fluid-flow and geomechanical simulations which can help analyzing the dynamic behavior of the accretionary prism methane hydrates at the Cascadia and other active ocean margins.
Presentation Date: Monday, October 15, 2018
Start Time: 1:50:00 PM
Location: Poster Station 7
Presentation Type: Poster