CyberShake Software Plan
We are currently development CyberShake 2.0 that will have the following capabilities:
- UCERF2.0-based extended earthquake rupture forecast
- 1.0Hz reciprocity-based seismogram synthesis using 3D velocity model
- Addition of 10Hz stochastic to 1Hz deterministic seismograms
- Spectral acceleration calculation
- OpenSHA plotting of hazard curves
Our immediate CyberShake goal is to calculate deterministic 3D seismograms up to 1.0Hz using SRF-format ruptures using both wave propagation simulations and reciprocity-based seismogram synthesis.
We plan to base our forward CyberShake deterministic simulations on the latest Olsen/Roten version of AWP-ODC which was used in the M8 wave propagation simulations. This code is available for use.
SGT codes
A large fraction of our CyberShake computing time is spent calculationg SGTs. Our current plan is to use a new version of AWP-ODC, called AWP-ODC-SGT, to calculate our SGT. We plan to continue to use the Graves seismogram synthesis to calculate seismograms from CyberShake SRF's and AWP-ODC-SGT SGTs.
The current design concept is that we will develop a version of AWP-ODC-SGT that outputs SGT's in the Graves SGT code format. Then, the current Graves seismogram synthesis code will use these SGT's, regardless of the fact they were calculated by AWP-ODC-SGT.
To get this system working, we have modified AWP-ODC-SGT to write SGTs. We are now working to compare the SGT's output by Graves code to ones from AWP-ODC-SGT.
We are seeing again that we need to do this code comparison step-by-step, establishing matching results on simple problems, then adding complexity and comparing again. Here are the proposed simulations that we will compare.
We have defined different types of simulations, based on the sources used. We have impulse sources, that are applied at the surface in one horizontal direction. We have point sources, that are applied at mesh point in the velocity model. We have extended SRF sources, that were calculated by CyberShake Rupture generator.
We also have forward simulations that produces seismograms, SGT simulations that produce SGTs, and seismogram synthesis simulations that produce seismograms. Seismogram frequencies are starting at 0.5Hz. Once that works, we will increase to 1.0Hz.
Here are a list of specific comparisons that we plan to perform to support this code comparison.
- Modify both CyberShake codes to output velocities, because velocity comparisons may be easier.
- Pre-filtered impulse simulation in center of homogeneous volume, 30km x 40km x 20km (small region), output velocities from both SGT codes and compare at 0.5Hz
- Pre-filtered impulse simulation in center of homogeneous volume, 60km x 80km x 40km (medium region), output velocities from both SGT codes and compare at 0.5Hz
- Pre-filtered impulse simulation at surface of homogeneous volume, 30km x 40km x 20km (small region), output stresses and velocities from both SGT codes and compare at 0.5Hz
- Pre-filtered impulse simulation in 1D model volume output with rotation with both codes output stresses and velocities and compare.
- Impulse simulation in 3D model volume with both codes, output stresses and velocities, and compare.
- Implement SGT and fault region management so Graves seismogram synthesis can find SGTs in SGT data sets.
- Impulse simulation in homogeneous volume with both codes, use Graves seismogram synthesis code to read both SGTs and compare seismograms.
- Impulse simulations in 3D model volume with both codes, use Graves seismogram synthesis of SRF source and compare seismograms.
Once these comparisons pass successfully, we increase the output frequency to 1.0Hz.
Extended Earthquake Rupture Forecast
We will extend our current UCERF2.0 rupture generator to produce an UCERF2.0-based set of rupture variations in Standard Rupture Format that contain frequencies up to 1.0Hz.
We require an updated set of fault geometries at higher resolution to support the increase from 0.5Hz to 1.0Hz.
