1. Comments on physical simulator models
David D. Jackson, UCLA

2. Forecast capabilities
Statistical distributions of earthquakes on prespecified faults
Magnitude frequency
Temporal (recurrence) for initiation, participation, and combinations
Spatial
Paleoseismic rate, sigma, slip rate, displacement distribution

3. Off-fault earthquakes
Not defined in phys sim models
Contribute to stress, and presumably to earthquake probability, on faults
Are counted in actual earthquake statistics (magnitude, temporal, spatial) but not in phys sim models
Participate in clustering models as sources and receivers, but not in phys sim models

4. UCERF2 Assignment of historic earthquakes to faults

5. UCERF2 Assignment of instrumental earthquakes to faults

6. Summary, UCERF2 Earthquakes on faults
total
M>7
After 1931
Yes 15 7 11 no 8 2 1
maybe 23 6
Total 46 19

7. Limits to forecasting power
Phys sim models are explicitly time-dependent (conditional on history), but history can’t be input or matched in simulations
Can’t be tested because they could forecast only on-fault quakes, which are not defined.
Paleoseis record is presumably recording on-fault quakes, but is not complete.
?Clustering studies show that small earthquakes are important in triggering, but phys sim models can include them only with massive calculations?.
Models depend on Coulomb stress, which hasn’t yet demonstrated clear forecasting ability. But simulators could help make the case by setting up initial conditions.

8. Conditional Stopping Probability in 10km segment boundary according to WGCEP2008

9. Smoothed seismicity and faults

10. Stochastic earthquake simulation, 100 m=6.5+ events