Vertical deformation

[brendanjmeade]

We want to add (or expose) modeling of vertical deformation.

Notes:

• This must be something that can be toggled on and off as observational constraints. I propose: "include_vertical_deformation": [0,1] in a config file. The default should be that vertical deformation is not included, 0. Even if verticals are not included as data they should be calculated and made part of the output. This will enable the analysis of predicted vertical displacements.
• There's already a place for storing vertical velocities in *_station.csv files, specifically the the up_vel and up_sig columns.
• There is one conceptually interesting note here. If there is only plate motion there is no vertical deformation because all motions are tangent to the Earth's surface in that case.
• Related to the point above vertical deformation is generated from elastic deformation. Remarkably I think we're already calculating this but are simply removing the columns and rows associated with these terms.
• Vertical deformation may be a direct constraint from GNSS data. It's also implicitly required for the analysis of InSAR LOS measurements. These are generated from the dot product of the 3D displacement/velocity vector (from the model) with a "look vector" that describes the angle at the satellite is observing the earth from. The look angle is typically steep (~70 degrees) so vertical deformation is a primary contributor.