IAG-IASPEI 2017

Presentation information

Oral

Joint Symposia » J07. Tracking the sea floor in motion

[J07-1] Tracking the sea floor in motion I

Thu. Aug 3, 2017 8:30 AM - 10:00 AM Room 401 (Kobe International Conference Center 4F, Room 401)

Chairs: Tadashi Ishikawa (Japan Coast Guard) , Diego Melgar (University of California, Berkeley)

9:15 AM - 9:30 AM

[J07-1-04] Preliminary Results of Realistic Interseismic Modeling and GPS-Acoustics Measurements on the Continental Slope of the Cascadia Subduction Zone

Diego Melgar1, David Chadwell2, David Schmidt3 (1.UC Berkeley, 2.Scripps Institution of Oceanography, 3.University of Washington)

Land-based GPS measurements suggest the megathrust is locked offshore along the Cascadia Subduction Zone. However, land-based data alone lack the resolution to constrain the how the slip deficit is distributed. Current efforts to constrain offshore crustal deformation using the GPS-Acoustic technique motivates refined, and more realistic models of the prism and forearc. Here we expand on efforts to create realistic, physics-based models of the deformation of the shallow subduction system. Our goal is to study what the relative importance is of different physical processes at play in the interseismic period, such as viscoelasticity of the upper mantle and plasticity of the wedge. In anticipation of renewed interest in expanding GPS-A studies in Cascadia, we have begun to use such realistic physics based models of the deformation of the shallow subduction system to make recommendations on what the optimal distribution of seafloor benchmarks should be in order to provide the most cost efficient solution to imaging the state of locking of the megathrust.

Here, we also discuss updates to current efforts to expand GPS-A coverage in Cascadia by utilizing Wavegliders to dramatically reduce ship costs. In July 2016, the GPS-A Wave Glider was launched on a month-long mission to two sites on the continental slope of the Cascadia Subduction Zone. One site is approximately 45 NM offshore central Oregon and the other approximately 50 NM offshore central Washington State. We will report on initial results of the GPS-A data collection and operational experiences of the mission. Wave Glider based GPS-A measurement have the potential to significantly increase the number and frequency of measurements of strain accumulation in Cascadia Subduction Zone and elsewhere.