RSQSim CyberShake

We are planning to perform CyberShake simulations using RSQSim as the ERF. This page documents the decisions and results.

Modifications from UCERF2 ERF

The biggest differences from the UCERF2 ERF is that RSQSim ruptures don't neatly fall into the source/rupture/rupture variation hierarchy, and the rupture surfaces are UCERF3 surfaces, so they fall on a triangular, not rectangular grid.

Rupture hierarchy

<Kevin, can you fill this in?>

Database changes

• In the Ruptures table, we are using the square root of the average element area for GridSpacing - basically, the side length if they were on a rectangular grid.
• In the Ruptures table, we are setting NumRows and NumCols to 0, but using the correct value for NumPoints.

Input file changes

• Since the rupture geometry files also expect GridSpacing, NumRows, and NumCols, we are using the same approach as in the database. GridSpacing is replaced by AveArea, and NumRows and NumCols are replaced by NumPoints.

Code changes

• A new version of DirectSynth, DirectSynth_RSQSim, was created, which takes in an input file consisting of a list of SRFs for processing.

Small-scale test

Initially, we are using a small RSQSim catalog (? kyrs, ? events) with elements with an average area of ~1.4 km^2, for testing on 4 CyberShake sites (USC, PAS, WNGC, SBSM).

Test seismograms

Seismograms were synthesized for site USC (1 Hz) for two RSQSim events.

event 74399, M6.64 on the Elsinore Fault	Seismograms at USC for event 74399
event 33801, M7.71 on the SAF, Garlock, and San Jacinto	Seismograms at USC for event 33801