Update Cascadia intraslab depths to SLAB2

• Update spatial PDFs for slab sources to use those derived from the SLAB2 (Hayes et al., 2018) model.
• Run sensitivity for slices vs depth varying.

See https://code.usgs.gov/ghsc/nshmp/nshmp-dev/-/issues/29 (internal) for details on required SLAB 2 depth extrapolations.

added 2023 ERF labels

assigned to @jaltekruse

changed the description

changed milestone to %NSHM Model and Tool Improvements

added To Do label

changed milestone to %Beta release of CONUS NSHM

marked the checklist item Update spatial PDFs for slab sources to use those derived from the SLAB2 (Hayes et al., 2018) model. as completed

changed the description

Punting sensitivities to new issue. See #38

closed