CEUS Site and Gulf Coast logic tree

Sites in the gulf coast (zSed) region should get 25% weight on the Chapman & Guo (2021) CPA model. This can be achieved by either:

• Having *_CPA flavors of GMMs; this will duplicate all CEUS calculations, but the epistemic uncertainty will be exposed in hazard.
• Imposing scale factors of 0.75 and 0.25 within NgaEast.SiteAmp_2023; no duplication of GMM calculations; ratio maps can be produced by disabling site (zSed) data.

changed milestone to %Finalize draft NSHM 2023

added 2023 GMM labels

The CPA implementation is additive (in log space) on top of the NGA-East site amp model and includes a site term correction. Therefore to implement 25% weight internally we just change the CPE term to 0.25 * (fCpa - cpaSiteCorr)

Also using this issue to update GMM test input files to include zSed column.

Resolved in !306 (merged)

closed