Add support for along-strike slip-variability

Created by: pmpowers-usgs

The 2007 NSHM Alaska model supported variable slip rates along the length of a fault.

Created by: pmpowers-usgs

The use of this model implies very long faults upon which ruptures "float".

Algorithm

• Given a rupture magnitude
• Compute rupture length using W&C length
• Compute the rupture rate based on length or area weight-averaged a-values that the rupture spans

If epistemic and/or aleatory uncertainty is to applied (as in the AK2007 model), then the rate should be distributed between the M+ and M- branches, possibly moment balancing in the process.

Use a custom MFD to store an array of rates with one value for each vertex in the corresponding fault trace .

Created by: pmpowers-usgs

Some time ago, a simplified inversion approach was used to generate a moment-balanced, UCERF3-like version of the Denali-Totschunda fault system. See https://github.com/usgs/nshm-ak-2007/tree/master/System