Assessment of Geohazards and Geodynamics by Integrated Gravimetric and Geodetic Methods

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Micro gravimetric monitoring with superconducting gravity meter is effective for estimating small subsurface mass change and redistribution caused by geohazards such as earthquakes, volcanism, and migration and leakage of injected CO2 into geological reservoirs. The gravity signals acquired at the Earth's surface, however, include the effects of surface displacement related to subsurface deformation, and hence, the gravity effect from surface deformation must be accurately estimated and separated from the measured gravity at the surface. This became possible by integrated geodetic techniques such as Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) network. In order to monitor, model, and assess geohazards and geodynamics by integrated gravimetric and geodetic methods (Fig. 1), I propose to deploy iGrav superconducting (SG), A-10 absolute (AG), and CG-5 spring gravimeters (RG) to three sites in western and northwestern Canada: 1) the Cascadia subduction zone (CSZ) in BC for earthquake monitoring, 2) the Kluane Lake Research Station (KLRS) in Yukon for induced seismicity and volcanic activity, and 3) the Field Research Station (FRS) geological CO2 storage in Brooks, AB for injected plume monitoring. iGrav SG is the key instrument which will be supported by A-10 and FG-5 AGs and CG-5 RG. Time-varying 2D and 3D gravity monitoring and subsurface modelling will be conducted by integrated SG-AG-RG. Surface displacement will be estimated and modelled by InSAR measurements and GNSS network data. A joint inversion modelling of gravity and ground deformation will be also conducted to derive a subsurface mass redistribution model. These novel methodologies have been developed by the applicant and proven effective in journal publications and patents. Gravity meters will be calibrated at the university Lab and deployed at three sites in turn for data acquisition, depending on the site's data quality and hazard events recorded in the gravity signals. This is a comprehensive gravimetric and geodetic research for a better understanding of the seismic geohazards and securing carbon storage. It also integrates the most advanced satellite radar remote sensing and geodetic technologies that can be readily applied elsewhere in Canada and around the world. This research will provide novel insight into the near-true behavior of tectonic activity through a more realistic geodynamic model. Future geohazards will cost human lives and cause property damage. If the detection of precursors of an earthquake is possible, it can be used for public safety and policy making. It is anticipated that the results from this study will provide new information about the density and mass balance variations, fluid flow and permeability measures, and pressure changes in the CO2 reservoirs, which will subsequently be integrated with the findings of other techniques, such as seismic monitoring, for better interpretation of CO2 storage changes.