Forecast Models: Two Years of Observations Provide Preliminary Support for Merging Smoothed Seismicity with Geodetic Strain

11 The Global Earthquake Activity Rate (GEAR1) seismicity model uses an optimized combination 12 of geodetic strain rates, hypotheses about converting strain rates to seismicity rates from plate 13 tectonics, and earthquake-catalog data to estimate global mw ≥ 5.767 shallow (≤ 70 km) seismicity 14 rates. It comprises two parent models: a strain rate-based model, and a smoothed-seismicity 15 based model. The GEAR1 model was retrospectively evaluated and calibrated using earthquake 16 data from 2005–2012, resulting in a preferred log-linear, multiplicative combination of the parent 17 forecasts. Since October 1, 2015, the GEAR1 model has undergone prospective evaluation within 18 the Collaboratory for the Study of Earthquake Predictability (CSEP) testing center. 19 We present initial prospective forecast test results for the GEAR1 model, its tectonic and 20 seismicity components, and for the first iteration of the strain rate-based model, during the period 21 October 1, 2015 to September 7, 2017. Observed earthquakes are consistent with the GEAR1 22 forecast, supporting a near-even contribution from geodetic strain rates and smoothed seismicity in 23 constraining long-term global shallow earthquake rates. Comparative test results likewise support 24