Back to M6.4 — Ridgecrest Earthquake Sequence

Observed vs Simulated — Goodness of Fit

A physics-based simulation of this earthquake, compared against the seismograms the network actually recorded. M6.4 Ridgecrest Earthquake Sequence · 2019-07-04 17:33:49 UTC

Download the full report (PDF) Includes per-station waveform and displacement pages. Generated 2026-08-04T23:25:00Z · BBP job job_e897f47e965e415c8b60

Before reading the result

What this measurement does and does not establish.

Emulated hardware. The simulation ran on arm64 under emulation. Amplitudes are not SCEC-reference-accurate, and this measurement cannot separate the platform from the model.

One realization. A single stochastic rupture, not an ensemble. The bias below is one draw; a second run with a different seed would give a different number.

What a pass means. Consistency with recordings at these 36 stations, for this event, under this velocity model, on this hardware, within a factor of 1.99. It is not a general statement about BBP and not a prediction of accuracy at an unrecorded site.

Result

Mean within pass band 36 stations · 63 spectral periods · BBP simulated

mean |bias|: 0.336; a factor of 1.4×
pass band: 0.69; a factor of 1.99×, declared before the run
sigma: 0.444; station-to-station scatter
cross-check: 0.428; recomputed here from the waveforms

The metric is ln(observed / simulated) RotD50 spectral acceleration, averaged over stations. Positive means the simulation under-predicts — real shaking was larger. Basis: BBP RotD50 residuals (authoritative).

Residual by period

Mean ln(obs/sim) at each spectral period. A structure responds at its own period, so agreement at one period says nothing about another.

Period	Bias	Simulation	Factor	vs. band
0.1s	-0.367	over-predicts by 44%	1.44×	within
0.3s	-0.514	over-predicts by 67%	1.67×	within
1s	-0.822	over-predicts by 127%	2.27×	outside band
3s	-0.216	over-predicts by 24%	1.24×	within

Read the mean with this in mind. The mean is within the pass band, but the residual at 1s is outside it — the simulation over-predicts by 127% at 1s. A single mean over periods cannot represent that.

Goodness of fit across the spectrum

Mean residual with its ±1σ band, against the pass band. Diamonds are the Broadband Platform’s own RotD50 residuals; the line is this report’s independent recomputation from the waveforms.

Where the stations are

Each station coloured by its PGA residual. Red means the simulation under-predicted the recording; blue means it over-predicted.

Map of compared stations coloured by residual

Station summary — three independent sources

36 stations with both a recording and a simulated seismogram. Scroll sideways for the full set of columns.

Station	Dist (km)	Vs30 BBP	Vs30 ShakeMap	Chan	PGA (g) ShakeMap	PGA (g) obspy	PGA (g) BBP	PGV (cm/s) ShakeMap	PGV (cm/s) obspy	PGV (cm/s) BBP	PGD (cm) obspy	PGD (cm) BBP	PGD obs/sim	ln(obs/ sim)	Flags
CI.CLC	14.9	331	331	HNE	0.2147	0.1927	0.2794	10.6	10.3	29.7	2.74	9.41	0.29x	-0.371	Inco,Outl
CI.Q0072	18.2	262	262	HNE	0.2112	0.2327	0.2383	31.2	33.7	43.0	13.68	17.55	0.78x	-0.024	—
CI.SRT	22.3	265	265	HNE	0.1577	0.1542	0.2199	17.7	17.9	18.9	6.67	10.01	0.67x	-0.355	—
CI.CCC	23.7	344	344	HNE	0.3817	0.3673	0.1455	26.6	27.1	15.0	3.70	5.58	0.66x	+0.926	—
CI.TOW2	26.2	266	266	HNE	0.1786	0.1754	0.1780	15.6	16.4	15.5	4.27	8.16	0.52x	-0.015	—
CI.SLA	28.7	599	599	HNE	0.0193	0.0689	0.1729	0.7	5.6	17.9	2.01	5.51	0.37x	-0.920	Inco,Outl
CI.LRL	29.8	618	618	HNE	0.1971	0.1841	0.1290	14.0	15.6	14.0	4.28	4.64	0.92x	+0.356	—
CI.WRC2	30.0	565	565	HNE	0.1310	0.1276	0.1666	9.6	9.8	9.6	1.57	5.27	0.30x	-0.267	Inco,Outl
CI.WBM	36.6	366	366	HNE	0.0549	0.1058	0.1072	4.5	9.2	9.6	1.83	4.90	0.37x	-0.013	Inco,Outl
CI.WVP2	39.2	658	658	HNE	0.0983	0.0938	0.0888	4.7	4.7	6.6	0.90	3.67	0.24x	+0.054	—
CI.WNM	39.4	556	556	HNE	0.0931	0.0768	0.0885	2.2	2.1	7.7	1.33	3.71	0.36x	-0.142	—
CI.WCS2	42.7	691	691	HNE	0.0781	0.0731	0.0662	5.9	5.9	5.5	0.81	3.98	0.20x	+0.099	Inco,Outl
CI.WRV2	48.4	353	353	HNE	0.0485	0.0475	0.1105	3.9	3.9	7.7	0.68	5.51	0.12x	-0.844	—
CI.WMF	55.7	602	602	HNE	0.0240	0.0235	0.0572	1.8	1.8	5.3	0.80	3.53	0.23x	-0.889	—
CI.DTP	57.7	710	710	HNE	0.0234	0.0219	0.0445	2.6	2.8	4.0	1.66	2.47	0.67x	-0.709	—
CI.WBS	60.5	730	730	HNE	0.0912	0.0876	0.0434	4.0	4.3	3.6	0.65	1.74	0.37x	+0.702	—
NP.1809	60.7	288	288	HNE	0.0321	0.0428	0.0821	2.3	2.7	9.4	0.93	5.55	0.17x	-0.652	—
CI.DAW	63.5	599	599	HNE	0.0139	0.0116	0.0385	0.7	0.7	2.9	0.26	1.65	0.16x	-1.196	—
NN.QSM	64.1	379	379	HHE	0.0308	0.0282	0.0751	2.3	2.2	5.5	0.42	3.72	0.11x	-0.979	Glit,Outl
CI.WOR	66.7	398	398	HNE	0.0563	0.0517	0.0688	1.7	1.5	3.9	0.50	1.54	0.32x	-0.285	—
CI.APL	69.8	583	583	HNE	0.0242	0.0222	0.0349	1.3	1.4	3.6	0.37	2.85	0.13x	-0.455	—
CE.43158	71.7	283	283	HNE	0.0363	0.0353	0.0645	2.9	4.6	6.4	1.30	4.37	0.30x	-0.603	—
CI.WHF	76.6	371	371	HNE	0.0548	0.0528	0.0469	2.7	2.7	2.7	0.53	1.22	0.43x	+0.118	—
CI.CCA	77.0	342	342	HNE	0.0250	0.0245	0.0531	3.8	3.8	5.3	1.55	3.89	0.40x	-0.774	—
CI.GSC	77.5	653	653	HNE	0.0212	0.0205	0.0337	1.6	1.4	2.5	0.41	2.64	0.16x	-0.500	—
CI.Q0068	78.7	343	343	HNE	0.0228	0.0207	0.0480	2.0	2.8	6.7	1.42	3.94	0.36x	-0.839	—
CI.HAR	79.4	344	344	HNE	0.0321	0.0312	0.0453	2.9	2.7	4.8	0.65	2.41	0.27x	-0.371	—
CI.LMR2	87.5	735	735	HNE	0.0210	0.0183	0.0277	1.8	1.7	2.0	0.45	0.78	0.58x	-0.417	—
CI.ISA	87.8	927	927	HNE	0.0196	0.0169	0.0242	1.0	1.1	1.3	0.31	0.74	0.41x	-0.359	—
CE.34349	88.6	373	373	HNE	0.0646	0.0641	0.0457	4.2	4.2	3.5	0.53	1.24	0.43x	+0.337	—
NN.GWY	92.2	684	684	HHE	0.0127	0.0127	0.0305	1.4	1.4	3.2	0.38	2.49	0.15x	-0.876	Glit,Outl
CI.HYS	93.6	349	349	HNE	0.0249	0.0234	0.0395	1.1	1.0	3.3	0.32	0.89	0.36x	-0.524	—
CI.TEH	94.9	794	794	HNE	0.0246	0.0237	0.0216	2.1	2.0	2.1	0.86	1.73	0.50x	+0.093	—
CI.WAS2	95.2	780	780	HNE	0.0274	0.0265	0.0269	1.5	1.4	1.7	0.33	0.69	0.48x	-0.015	—
CI.CWC	96.7	658	658	HNE	0.0126	0.0114	0.0224	0.8	0.7	2.1	0.38	1.97	0.19x	-0.679	—
CI.CGO	97.7	713	713	HNE	0.0145	0.0141	0.0262	1.3	1.2	1.9	0.36	1.38	0.26x	-0.620	—

ShakeMap = amplitudes the seismic network reported in stationlist.json. obspy = the same recordings fetched from FDSN and processed here. BBP = simulated. The first two should agree closely; where they do not, the ShakeMap quality flags usually explain why.
PGD is the animation pipeline's own number on both sides, read from the displacement each side hands to Blender — a different processing chain from the PGA and PGV columns, and from each other. See the displacement pages at the end.

Cross-check — how far apart are the two ‘observed’ sources?

The amplitudes the network reported in ShakeMap against the same recordings re-fetched and processed here. These should agree closely; where they do not, the ShakeMap quality flags usually explain why. A systematic offset here would be a processing fault, not physics.

Observed amplitude cross-check versus distance

Residual against distance

A trend with distance points at the attenuation model rather than the source: the simulation losing energy faster or slower than the real crust does.

Residual versus distance at four periods

Response spectra, station by station

Observed and simulated response spectra at every compared station.

Per-station detail

Nearest first. Open a station for its three-component waveform overlay and the displacement record that drives the shaking animations. Figures load when opened.

CI.CLC 14.9 km PGA obs 0.1927 g · sim 0.2794 g ln(obs/sim) -0.371

Observed versus simulated acceleration at CI.CLC

CI.Q0072 18.2 km PGA obs 0.2327 g · sim 0.2383 g ln(obs/sim) -0.024

Observed versus simulated acceleration at CI.Q0072

CI.SRT 22.3 km PGA obs 0.1542 g · sim 0.2199 g ln(obs/sim) -0.355

Observed versus simulated acceleration at CI.SRT

CI.CCC 23.7 km PGA obs 0.3673 g · sim 0.1455 g ln(obs/sim) +0.926

Observed versus simulated acceleration at CI.CCC

CI.TOW2 26.2 km PGA obs 0.1754 g · sim 0.1780 g ln(obs/sim) -0.015

Observed versus simulated acceleration at CI.TOW2

CI.SLA 28.7 km PGA obs 0.0689 g · sim 0.1729 g ln(obs/sim) -0.920

Observed versus simulated acceleration at CI.SLA

CI.LRL 29.8 km PGA obs 0.1841 g · sim 0.1290 g ln(obs/sim) +0.356

Observed versus simulated acceleration at CI.LRL

CI.WRC2 30.0 km PGA obs 0.1276 g · sim 0.1666 g ln(obs/sim) -0.267

Observed versus simulated acceleration at CI.WRC2

CI.WBM 36.6 km PGA obs 0.1058 g · sim 0.1072 g ln(obs/sim) -0.013

Observed versus simulated acceleration at CI.WBM

CI.WVP2 39.2 km PGA obs 0.0938 g · sim 0.0888 g ln(obs/sim) +0.054

Observed versus simulated acceleration at CI.WVP2

CI.WNM 39.4 km PGA obs 0.0768 g · sim 0.0885 g ln(obs/sim) -0.142

Observed versus simulated acceleration at CI.WNM

CI.WCS2 42.7 km PGA obs 0.0731 g · sim 0.0662 g ln(obs/sim) +0.099

Observed versus simulated acceleration at CI.WCS2

CI.WRV2 48.4 km PGA obs 0.0475 g · sim 0.1105 g ln(obs/sim) -0.844

Observed versus simulated acceleration at CI.WRV2

CI.WMF 55.7 km PGA obs 0.0235 g · sim 0.0572 g ln(obs/sim) -0.889

Observed versus simulated acceleration at CI.WMF

CI.DTP 57.7 km PGA obs 0.0219 g · sim 0.0445 g ln(obs/sim) -0.709

Observed versus simulated acceleration at CI.DTP

CI.WBS 60.5 km PGA obs 0.0876 g · sim 0.0434 g ln(obs/sim) +0.702

Observed versus simulated acceleration at CI.WBS

NP.1809 60.7 km PGA obs 0.0428 g · sim 0.0821 g ln(obs/sim) -0.652

Observed versus simulated acceleration at NP.1809

CI.DAW 63.5 km PGA obs 0.0116 g · sim 0.0385 g ln(obs/sim) -1.196

Observed versus simulated acceleration at CI.DAW

NN.QSM 64.1 km PGA obs 0.0282 g · sim 0.0751 g ln(obs/sim) -0.979

Observed versus simulated acceleration at NN.QSM

CI.WOR 66.7 km PGA obs 0.0517 g · sim 0.0688 g ln(obs/sim) -0.285

Observed versus simulated acceleration at CI.WOR

CI.APL 69.8 km PGA obs 0.0222 g · sim 0.0349 g ln(obs/sim) -0.455

Observed versus simulated acceleration at CI.APL

CE.43158 71.7 km PGA obs 0.0353 g · sim 0.0645 g ln(obs/sim) -0.603

Observed versus simulated acceleration at CE.43158

CI.WHF 76.6 km PGA obs 0.0528 g · sim 0.0469 g ln(obs/sim) +0.118

Observed versus simulated acceleration at CI.WHF

CI.CCA 77.0 km PGA obs 0.0245 g · sim 0.0531 g ln(obs/sim) -0.774

Observed versus simulated acceleration at CI.CCA

CI.GSC 77.5 km PGA obs 0.0205 g · sim 0.0337 g ln(obs/sim) -0.500

Observed versus simulated acceleration at CI.GSC

CI.Q0068 78.7 km PGA obs 0.0207 g · sim 0.0480 g ln(obs/sim) -0.839

Observed versus simulated acceleration at CI.Q0068

CI.HAR 79.4 km PGA obs 0.0312 g · sim 0.0453 g ln(obs/sim) -0.371

Observed versus simulated acceleration at CI.HAR

CI.LMR2 87.5 km PGA obs 0.0183 g · sim 0.0277 g ln(obs/sim) -0.417

Observed versus simulated acceleration at CI.LMR2

CI.ISA 87.8 km PGA obs 0.0169 g · sim 0.0242 g ln(obs/sim) -0.359

Observed versus simulated acceleration at CI.ISA

CE.34349 88.6 km PGA obs 0.0641 g · sim 0.0457 g ln(obs/sim) +0.337

Observed versus simulated acceleration at CE.34349

NN.GWY 92.2 km PGA obs 0.0127 g · sim 0.0305 g ln(obs/sim) -0.876

Observed versus simulated acceleration at NN.GWY

CI.HYS 93.6 km PGA obs 0.0234 g · sim 0.0395 g ln(obs/sim) -0.524

Observed versus simulated acceleration at CI.HYS

CI.TEH 94.9 km PGA obs 0.0237 g · sim 0.0216 g ln(obs/sim) +0.093

Observed versus simulated acceleration at CI.TEH

CI.WAS2 95.2 km PGA obs 0.0265 g · sim 0.0269 g ln(obs/sim) -0.015

Observed versus simulated acceleration at CI.WAS2

CI.CWC 96.7 km PGA obs 0.0114 g · sim 0.0224 g ln(obs/sim) -0.679

Observed versus simulated acceleration at CI.CWC

CI.CGO 97.7 km PGA obs 0.0141 g · sim 0.0262 g ln(obs/sim) -0.620

Observed versus simulated acceleration at CI.CGO

Provenance

Simulation

produced by: BBP simulated
BBP job id: job_e897f47e965e415c8b60
BBP version: 22.4.0
method: GP
realizations: 1 of 1 succeeded — a single stochastic rupture, not an ensemble; the bias below is one draw
realization used: r0001
sites in job spec: —
job submitted: 2026-08-04T23:11:07Z
per-site Vs30 from: submit-time record (/app/plots/gof_work/ci38443183/compare/station_specs.json)

Source parameters

magnitude used: —
hypocentre: —
depth: —
strike / dip / rake: —
mechanism source: USGS moment tensor, nodal plane 1 — the conjugate plane is equally consistent with the tensor and gives different amplitudes

Velocity model

region used: Mojave500
native for this location: Mojave500 — not installed, so the run is approximate. LABasin500 carries a deep sedimentary basin that Ridgecrest does not have, which would amplify 0.3-1 s motion.
calibration: M6.4 against GP's ~M5.5 floor
platform: arm64 under emulation — amplitudes are not SCEC-reference-accurate; this number measures BBP plus Rosetta and cannot separate them

Observed data and processing

Station selection

search radius: 100.0 km
policy: all usable within radius
stations on event: 1018
without FDSN code: 0 — cannot be queried at all
candidates: 39
usable records: 36 (3 returned no usable 3-component set)
in this report: 36 with both observed and simulated
distance range: 14.9 – 97.7 km

Instrumentation

channel priority: HN?, EN?, HH?, BH?, EH?
channels used: HH, HN
data centres: EARTHSCOPE, NCEDC, SCEDC
mixed instrument types: yes — strong-motion and broadband are both present, which puts a second variable into the residual
Vs30 source: ShakeMap stationlist (per-station)

Signal processing

window: origin −60.0 s to +300.0 s (requested)
records not starting as requested: 5 of 36 — triggered instruments whose data begins later. Each trace's true start is measured and used; assuming the requested lead would misplace them.
response removal: to acceleration and velocity separately, pre-filter (0.05, 0.1, 20.0, 25.0) Hz
resampled to: 100.0 Hz
time origin: t = 0 is the rupture origin for both observed and simulated traces on every overlay

How to read this report

The metric

definition: ln(observed / simulated) RotD50 spectral acceleration, averaged across stations at each period.
sign: POSITIVE means the simulation under-predicts — real shaking was larger. NEGATIVE means it over-predicts.
scale: It is a log ratio: ±0.10 is about ±10%, ±0.69 is a factor of 2, ±1.10 is a factor of 3.
sigma: The station-to-station spread around that average. A large sigma with a small bias means the model is right on average and wrong site by site.

Reading the pattern

short-period poor, long-period good: Points at high-frequency attenuation or near-surface site response rather than the source.
long-period poor, short-period good: Points at the source — corner frequency, stress drop — or at basin response in the velocity model.
one station far off: Usually 3D site or directivity effects that a 1D layered velocity model cannot reproduce by construction. Check whether it is driving the sigma before treating it as model error.

What this does not tell you

: A pass means the simulation is consistent with recordings at these stations, for this event, under this velocity model, on this hardware. It is not a general statement about BBP, and it is not a prediction of accuracy at an unrecorded site.