CyberShake Deterministic MCEr Calculations

Original CyberShake MCEr results have been presented which include all UCERF2 ruptures, including aleatory magnitude variability. Is has come to our attention that the NSHMP does not include aleatory magnitude variability when calculating deterministic hazard spectrum and have modified our calculation procedure to remove the aleatory variability. These results are not yet final, pending receiving a list of sources/magnitudes used by the NSHMP for UCERF2 based deterministic calculations. Once we have that list we can verify our approach.

For more background on a the algorithm to remove aleatory magnitude variability, see this page.

Initial results, 2s RotD100

Dataset	Probabilistic MCER (UNCHANGED)	Deterministic MCER	Deterministic Lower Limit (UNCHANGED)	Combined MCER results
Original CyberShake 2s
New Deterministic Algorithm, 2s

Governing Scatter Plots

I have generated a new set of plots which shows the value that governs at each CyberShake site. This shows where the (now lower) deterministic values govern the MCEr value at 2s.

As a reminder, the final combined MCEr value is min(probabilistic, max(deterministic, deterministic_lower_limit)).

BLUE: Probabilistic Value Governs

RED: Deterministic Value Governs

GRAY: Deterministic Lower Limit Value Governs

Original Scatter

As you can see below, originally all sites were governed by the probabilistic values (all sites are blue).

New Deterministic Algorithm Scatter

Now a number of sites are governed by the deterministic values, especially along the San Andreas Fault