The GEM Global Block Model is a research dataset that contains a comprehensive, globally complete set of >7000 active faults, combined with a subdivision of the entire Earth surface into ~2000 tectonic plates or microplates (blocks), and a set of three-dimensional meshes of subduction interfaces. 

The faults are boundaries between blocks, and the slip rates of the faults (proportional to the seismic activity of the faults) are determined by the relative motion of the blocks on either side of the faults. The fault geometries are from a near-complete remapping of Earth’s deforming regions, based in part on existing mapping (such as the previous version of the GEM Global Active Faults Database or GEM GAF-DB), as well as interpretations of high-resolution topography, seismicity and geodetic data, to maximize completeness, accuracy, and mapping style specifically for seismic hazard assessment. 

The block motions are determined through joint inversion of geodetic velocity data — primarily GNSS observations supplemented by InSAR-derived velocity fields from the COMET LiCSAR processing system — and geologic fault slip rates spanning decadal to Quaternary timescales. The primary output is the set of active faults with complete, internally-consistent slip rates and formal uncertainties, and subduction interfaces with spatially-variable coupling estimated simultaneously with the slip rates. 

These fault data may be easily used to build and evaluate seismic source models using the OpenQuake software suite. The GEM Global Block Model is a work in progress, and both block geometries and derived fault parameters are subject to revision as new geodetic and geologic data are incorporated. This dataset will soon be made available for direct download.