Towards the First Global Block Model

Abstract:

Geodetic observations of interseismic deformation can be explained, to first order, by the combined effects of plate rotations and earthquake cycle processes along seismogenic fault systems, as a result of the repeated accumulation and release of elastic strain over the course of decadal to millennial intervals. Here we present the model set up, data sources, and preliminary results from the first block model to cover the entire globe, thus unifying both large scale plate motions with local earthquake cycle effects at known seismogenic fault systems. An initial reference model comprised of the tectonic plates and refined with the addition of regional scale models (e.g. Western US and Japan) results in ~7,500 fault segments, >200 blocks, and three-dimensional subduction zone fault interfaces defined by historic- and micro-seismicity, seismic reflection, and gravity data, where GPS station density is sufficient to resolve locking patterns and slip rates on more complex fault geometries. Using spherical block theory, we invert ~19,000 GPS velocities from across the globe to estimate fault slip rates, plate motions, and spatially varying interplate coupling along subduction zones with a mean residual velocity of ~2.3 mm.