Southern California Earthquake Center Triggering Models vs. Smoothed Seismicity PG = 1.35/eqk PG = 10/eqk Information gain per earthquake Reference forecast Testing region:California Target events:M ≥ 3.95 Testing period: Testing method:T-test PG = probability gain = P / P 0 IG = information gain = log e (PG) STEP model

Southern California Earthquake Center Japan and NZ Testing Regions Testing region Model class 1 day3 month1 year3 yearTotal All Japan Mainland Kanto Total day 3 month 6 month 5 year Total New Zealand

Southern California Earthquake Center Number of earthquakes Forecast Testing region:New Zealand Target events:M ≥ 4 (ETAS, PPE-1d), M ≥ 5 (PPE-3m, PPE-5y) Testing period:4 Sept Mar 2011 Testing method:N-test N obs = 17 (M ≥ 5) N obs = 271 (M ≥ 4) 209 are Darfield aftershocks Darfield Aftershock Forecasting (Gerstenberger & Rhoades)

Southern California Earthquake Center Information gain per earthquake Reference forecast Testing region:New Zealand Target events:M ≥ 4 (PPE-1d), M ≥ 5 (PPE-3m, PPE-5y) Testing period:4 Sept Mar 2011 Testing method:T-test PG = 99/eqk PG = 544/eqk PG = 1480/eqk ETAS model Darfield Aftershock Forecasting (Gerstenberger & Rhoades)

Southern California Earthquake Center CSEP Testing Results Comparative evaluations have quickly identified errors in model implementation –effective method for model verification (debugging) 5-yr RELM testing program has been effective in ranking long-term forecasting performance for M ≥ 5 target events in California –RELM paper by Zechar, Schorlemmer, et al. Aftershock triggering models (e.g., STEP, ETAS) obtain probability gains of relative to seismicity averaging models (e.g. PPE, TripleS) –Substantially more information gain can be obtained by updating forecasts more frequently than at 1-day intervals Adaptive triggering models out-perform those with time-independent parameters –Gerstenberger’s STEP model currently shows the best short-term performance in California; adaptive models in NZ and Japan are still being evaluated

Southern California Earthquake Center CSEP Plans Monitor the performance of 91 CSEP/Japan and 15 CSEP/NZ forecasting models during the active phases of the Tohoku and Darfield sequences –Reduce the updating interval for short-term forecasts from 1 day to 1 hr or less –Improve procedures for adapting forecasts to changes in the seismic environment Incorporate forecasting models based on physical hypotheses about earthquake generation –e.g., Coulomb stress function, rate/state friction, dynamic vs. static triggering, slow slip events, tidal triggering –Expand prospective testing to models based on non-seismic data Evaluate hypotheses critical to forecasting large earthquakes –e.g., fault segmentation, maximum magnitude, characteristic earthquakes, strongly coupled seismic gaps –Expand global testing program –Include model classes for legacy methods; e.g., M8/MSc Develop CSEP capabilities to support operational earthquake forecasting –Prospectively test candidate forecasting procedures –Unify forecasting across temporal and spatial scales (e.g. long-term & short-term) –Reduce testing latency by modeling catalog completeness and accuracy –Expand retrospective testing over the entire history of instrumental catalogs –Initiate model testing using recorded ground motions Support other prospective testing activities, including earthquake early warning