gmsim_v18.5.1

This is a modification of gmsim_v16.1 based on the work of Robin Lee in 2017/2018. This version implements a single change:

Changing the HF path duration from D_p = 0.07R to the Boore and Thomson (2014) path duration developed using the NGA-West2 database.

This change to increase the HF path duration was a result of the durations being identified as too short when compared to observed ground motions.

INSERT PLOTS AND EVIDENCE HERE FOR THE MODIFICATION

The computational implementation of this modification is to change the "hf_path_dur" variable in the params.py file to '11':

hf_path_dur = '11'

---More details needed here.