Hello, I’m geologist and new with PyLith. I try to obtain strong ground motions simulations on surface (e.g. accelerograms) as result of megathrust earthquake rupture, how can obtain these through PyLith tools? I run all 2D and 3D examples, and got familiar with coseismic slip. Thanks for your help.
Constructing the model will be similar to the mesh for the 3D subduction zone example (
examples/3d/subduction). However, you will need a much finer mesh in order to run a dynamic model with seismic wave propagation (generally you will need at least 10-12 cells per the smallest local shear wavelength).
For dynamic prescribed slip ground-motion simulations, you will need to generate a rupture model (slip, rise time, and slip initiation time on the fault surface) outside of PyLith. You will also need the 3D elastic properties as a spatial database.
You can select output at select point locations using the OutputSolnPoints object. It will write the displacement or velocity time histories. You can differentiate as necessary to get acceleration.
With the finite-element model, the rupture model, and 3D elastic properties, it is relatively easy to create the simulation configuration (
.cfg) file following the examples. Note that you will need a large cluster to run to frequencies higher than about 1 Hz.
Thanks a lot. And is it possible to obtain synthetics waveforms in 2D first, in order to get more expertise with pylith, before to try and work with the 3D simulations?
Yes. We highly recommend starting in 2D before going to 3D. See
examples/2d/subduction for a quasistatic subduction zone example. As I mentioned in my previous post, you will need a much finer mesh for a dynamic simulation, but the general procedure for constructing the finite-element mesh is the same.