Revised Tectonic Forecast of Global Shallow Seismicity Based on Version 2.1 of the Global Strain Rate Map

A major upgrade of the Global Strain Rate Map, version 2.1, uses far more geodetic data, systematic data processing, more modeled plates and plate boundaries, an improved algorithm, and a finer spatial grid than version 1 (Kreemer et al., 2014). We convert this model to an indefinite-term tectonic forecast of shallow seismicity on a fine global grid, using the assumptions of Bird et al. (2010) and similar algorithms. One new feature is smoothing of model strain rates, and thus forecast seismicity, around offshore plate boundaries where strain rates are not controlled by local geodetic data. Another is incorporation of velocity-dependent seismic coupling in subduction zones and continental convergent boundaries (Bird et al., 2009). The seismicity model is constructed in six progressively more complex versions. Only catalog years 1977–2004 are used for calibration, leaving years 2005–2012 available for retrospective tests. Tests of forecast success that are independent of total earthquake rate and that use no declustering show success comparable to that of one mature, optimized smoothed-seismicity algorithm. Online Material: FORTRAN 90 codes to generate seismicity forecasts.