Intensity Lab
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II

Max Est. MMI

4 km SE of Piru, CA

Magnitude3.8
Depth10.7 km
Time 2026-09-30T03:00:27.240000Z UTC: 2026-09-30T03:00:27.240000Z
USGS ID ci41340823
ShakeMap View USGS ↗

Engineering Ground Motion Parameters

GMPE predictions provide an independent check on the ShakeMap interpolated intensities above. ShakeMap relies on seismic station recordings; in areas with sparse station coverage — or for large teleseismic events and earthquakes outside dense West Coast networks — ShakeMap MMI can be inaccurate. A significant difference between ShakeMap and GMPE estimates is a signal that the ShakeMap result should be treated as preliminary. Also includes site Vs30 values and raw ground motion parameters (PGA/PGV).

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Est. Vs30 Values

Estimated shear-wave velocity in the upper 30 m used in GMPE calculations. Ref. column shows the 760 m/s rock-site reference for comparison.

Location Ref. (760 m/s) Est. Vs30 (m/s)
Piru
CA 		760 384
Val Verde
CA 		760 351
Simi Valley
CA 		760 294

MMI vs Distance — Default Vs30 (760 m/s)

All methods using the 760 m/s rock-site reference. ShakeMap values are independent of Vs30.

MMI vs distance — default Vs30

MMI vs Distance — Est. Vs30

GMPEs use the Est. Vs30 values shown in the table above. ShakeMap values are independent of Vs30.

MMI vs distance — Est. Vs30

GMPE Residual — Observed − Predicted MMI

Signed residual at each seismic station. Positive values mean the GMPE underestimated shaking; negative values mean it overestimated. The dashed line at zero indicates perfect agreement.

GMPE residual plot

GMPE Predicted vs. Observed MMI at Seismic Stations

Each point is one seismic station. Points on the dashed 1:1 line indicate perfect agreement; above the line = GMPE underestimated shaking; below = overestimated.

GMPE predicted vs observed scatter

GMPE Performance — Station Observations

Statistics computed by comparing each GMPE's predicted MMI against ShakeMap observed MMI at seismic stations. Bias = mean(observed − predicted). Lower RMSE indicates better overall agreement with instrumental measurements.

GMPE Bias Sigma RMSE
ASK14 +0.10 0.33 0.34
BSSA14 +0.10 0.33 0.34
CY14 +0.10 0.32 0.34
CB14 +0.10 0.32 0.34
Bias > 0: GMPE underestimated shaking at stations. Bias < 0: GMPE overestimated shaking.

Peak Ground Motion — Seismic Station Observations

Recorded PGA and PGV at seismic stations, sorted by highest PGA. Top 25 stations shown. MMI (PGA) and MMI (PGV) are independent conversions via Worden et al. (2012) GMICE.

Station PGA (g) MMI (PGA) PGV (cm/s) MMI (PGV)
Fillmore (CI.FMO) 0.0075 Not felt(I) 0.214 Weak(II)
Good Enough Ridge, Los Padres NF (CI.GDF) 0.0033 Not felt(I) 0.106 Weak(II)
Moorpark (CI.MOP) 0.0032 Not felt(I) 0.106 Weak(II)
South Mountain (CI.SMT) 0.0031 Not felt(I) 0.247 Weak(II)
Mesa Elementary School (CI.MES) 0.0025 Not felt(I) 0.094 Weak(II)
Newbury Park (CE.24857) 0.0020 Not felt(I) 0.075 Weak(II)
Santa Clara (CI.STC) 0.0016 Not felt(I) 0.061 Weak(II)
Pardee (CI.PDE) 0.0015 Not felt(I) 0.039 Not felt(I)
Hungry Valley SVR State Park (CI.HRV) 0.0014 Not felt(I) 0.055 Not felt(I)
Camarillo (CI.CLO) 0.0013 Not felt(I) 0.078 Weak(II)
Casitas Dam (CI.CDM) 0.0011 Not felt(I) 0.036 Not felt(I)
Ventura (CE.25340) 0.0011 Not felt(I) 0.048 Not felt(I)
Lakeview (CE.35511) 0.0010 Not felt(I) 0.023 Not felt(I)
Del Valle (CI.DTC) 0.0010 Not felt(I) 0.057 Weak(II)
Camp Hess Kramer (CI.CHK) 0.0010 Not felt(I) 0.040 Not felt(I)
Summit Elementary School (CI.SES) 0.0009 Not felt(I) 0.044 Not felt(I)
Lockwood Valley Maintenance Yard (CI.LMY) 0.0008 Not felt(I) 0.046 Not felt(I)
Oxnard (CE.25325) 0.0008 Not felt(I) 0.024 Not felt(I)
Channel Island (CI.CHI) 0.0008 Not felt(I) 0.029 Not felt(I)
Choke Cherry (CI.CRY) 0.0008 Not felt(I) 0.035 Not felt(I)
Mount Pinos (CI.MPI) 0.0006 Not felt(I) 0.029 Not felt(I)
Levy (CI.LVY) 0.0006 Not felt(I) 0.034 Not felt(I)
Burnt Peak (CI.BTP) 0.0006 Not felt(I) 0.029 Not felt(I)
Point Dume (CI.PTD) 0.0006 Not felt(I) 0.030 Not felt(I)
West Side (CI.WSS) 0.0006 Not felt(I) 0.030 Not felt(I)
Source: USGS ShakeMap station recordings (view ShakeMap). PGA in g (fraction of gravitational acceleration); PGV in cm/s. The observed MMI shown on the map uses ShakeMap's reported instrumental intensity where available, or max(MMI from PGA, MMI from PGV) otherwise.

Ground Shaking Intensities — Interpolated ShakeMap MMI

3 sites
Location MMI Description
Piru
CA 		Weak(II)
Val Verde
CA 		Not felt(I)
Simi Valley
CA 		Weak(II)

Seismic Station Observed MMI

MMI values are derived directly from observed ground motion measurements at seismic stations and are not spatially interpolated.

3 stations
Station MMI Description
Del Valle (CI.DTC) Weak(II)
Fillmore (CI.FMO) Weak(III)
Oat Mountain (CI.OAT) Not felt(I)