Refactor slab sources to use depth in spatial PDF
Addresses tasks in #173 (closed) with the exception of Cascadia 2018 slab conversion. Subset of slab sources used in test model were converted and tests passed without modification.
Maintenance scheduled for Tuesday, December 23, from 5 PM to 7 PM ET.
Addresses tasks in #173 (closed) with the exception of Cascadia 2018 slab conversion. Subset of slab sources used in test model were converted and tests passed without modification.