2003 PRVI GMM - custom flavors

Additional GMMs are required for the PRVI 2003 implementation:

• Spudich et al. (1999) is used for crustal zone sources
• Subduction sources use Sadigh and Youngs [0.5 wt. each] out to 58 km and Youngs [1.0 wt.] at larger distances (similar to Alaska)

mentioned in merge request !444 (merged)

Resolved in !444 (merged) !445 (merged)

closed

added GMM label