Change the _get_intra_event_std function of ASK14 (GMPE)

[g-weatherill]

In the Abrahamson et al (2014) GMPE the _get_intra_event_std function raises an error if the phi_al term is less than the phi_amp term to avoid taking the square root of a negative number (https://github.com/gem/oq-engine/blob/master/openquake/hazardlib/gsim/abrahamson_2014.py#L364). This situation happens for IMTs with periods longer than 5 and for magnitudes smaller than about 4.3 - 4.4.

The authors of the GMPE have addressed this in their hazard code, and simply set phi_amp to be 0.99 * phi_al in this circumstance (https://github.com/abrahamson/HAZ/blob/master/HAZ%20files/NGAWest2.F#L3098). As raising an error causes the calculation to fail for reasons that might be cryptic to the users, I recommend to adopt the same adjustment here rather than raising an error.

[mmpagani]

I’m fine with the suggested adjustment. m

…

In the Abrahamson et al (2014) GMPE the `_get_intra_event_std` function raises an error if the `phi_al` term is less than the `phi_amp` term to avoid taking the square root of a negative number (https://github.com/gem/oq-engine/blob/master/openquake/hazardlib/gsim/abrahamson_2014.py#L364). This situation happens for IMTs with periods longer than 5 and for magnitudes smaller than about 4.3 - 4.4. The authors of the GMPE have addressed this in their hazard code, and simply set `phi_amp` to be `0.9 * phi_al` in this circumstance (https://github.com/abrahamson/HAZ/blob/master/HAZ%20files/NGAWest2.F#L3098). As raising an error causes the calculation to fail for reasons that might by cryptic to the users I recommend to adopt the same adjustment here, rather than raising an error. -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: #3270