SW4 seems to only read first set of point sources from multi-segment SRF rupture #210
Description
Hello! I'm working on simulating the M7.1 Ridgecrest earthquake using SW4. I've built an SRF version 2.0 file with four fault segments from a published inversion model of the earthquake (Goldberg et al., 2020). Following the SRF 2.0 format, I have the header for the four planes, which is then followed by four groups of point sources separated by the POINTS labels for the four segments. The four segments have 2130, 380, 270, and 340 point sources each, so the entire rupture model should have 3120 point sources.
When I run SW4 with my SRF file organized such that the largest fault segment (2130 point sources) has its points first in the order in the SRF, SW4 reads the file and says the following:
Opened rupture file 'RC_M7_multiseg.srf'
Version = 2.0
Number of segments in header block: 4
Seg #1: elon=-117.533, elat=35.7161, nstk=21, ndip=20, len=63.5649, wid=23.5743
stk=318.522, dip=89.525, dtop=0.1496, shyp=8.6493, dhyp=7.9268
Seg #2: elon=-117.539, elat=35.7199, nstk=4, ndip=19, len=10.399, wid=23.5668
stk=309.45, dip=89.9, dtop=0.1797, shyp=4.6311, dhyp=6.6393
Seg #3: elon=-117.651, elat=35.8163, nstk=3, ndip=18, len=6.685, wid=23.5687
stk=309.84, dip=89.9, dtop=0.1226, shyp=3.3287, dhyp=7.4848
Seg #4: elon=-117.439, elat=35.6097, nstk=4, ndip=17, len=12.172, wid=23.0142
stk=319.76, dip=88.9213, dtop=0.0924, shyp=6.0854, dhyp=8.7137
Number of point sources in data block: 2130
Read npts=2130, made 2054 point moment tensor sources, nu1=2054, nu2=0, nu3=0
It seems that SW4 is only reading the first block of point sources corresponding to the first listed fault segment?
As another check, I changed the order of the segments in the SRF such that the 340 point source fault is listed first. In this case SW4 reads the file and similarly says the following:
Opened rupture file 'RC_M7_multiseg_newsegorder.srf'
Version = 2.0
Number of segments in header block: 4
Seg #1: elon=-117.439, elat=35.6097, nstk=4, ndip=17, len=12.172, wid=23.0142
stk=319.76, dip=88.9213, dtop=0.0924, shyp=6.0854, dhyp=8.7137
Seg #2: elon=-117.651, elat=35.8163, nstk=3, ndip=18, len=6.685, wid=23.5687
stk=309.84, dip=89.9, dtop=0.1226, shyp=3.3287, dhyp=7.4848
Seg #3: elon=-117.539, elat=35.7199, nstk=4, ndip=19, len=10.399, wid=23.5668
stk=309.45, dip=89.9, dtop=0.1797, shyp=4.6311, dhyp=6.6393
Seg #4: elon=-117.533, elat=35.7161, nstk=21, ndip=20, len=63.5649, wid=23.5743
stk=318.522, dip=89.525, dtop=0.1496, shyp=8.6493, dhyp=7.9268
Number of point sources in data block: 340
Read npts=340, made 329 point moment tensor sources, nu1=329, nu2=0, nu3=0
The Mw that SW4 calculates based on my SRFs (6.9 and 6.4 for the above examples respectively) is also lower than I expect given that the SRF is based off of an inversion for the M7.1 Ridgecrest mainshock.
I'm wondering if this is a bug in the software or if I have an issue with my SRF file. I don't think I'm able to attach the SRF, but here's a screenshot of the beginning of the file where the largest fault segment is first, as well as one of the transition points to the next segment deeper into the file.
SW4 runs fine and outputs waveforms as expected - I'm just not sure it's using all of the point sources.
Thank you!