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II

Max Est. MMI

5 km NW of Pinnacles, CA

Magnitude4.0
Depth5.4 km
Time 2026-08-11T10:19:08.260000Z UTC: 2026-08-11T10:19:08.260000Z
USGS ID nc75415717
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)
Soledad
CA
760 231
Gonzales
CA
760 228
Greenfield
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 +0.14 0.40 0.42
BSSA14 +0.13 0.37 0.40
CY14 +0.13 0.37 0.40
CB14 +0.13 0.36 0.38
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)
Mount Johnson (NC.BJOB) 0.0366 Light(IV) 1.050 Light(IV)
Big Mountain #3 (NC.BBGB) 0.0137 Weak(II) 0.712 Light(IV)
Panoche Road (NC.BPA) 0.0118 Weak(II) 0.586 Weak(III)
Shirttail Gulch (NC.BSG) 0.0097 Weak(II) 0.771 Light(IV)
Crazy Canyon #3 (NC.PCC) 0.0051 Not felt(I) 0.255 Weak(II)
Cienega Road (NC.BCGB) 0.0049 Not felt(I) 0.077 Weak(II)
Pinnacle Vineyards (NC.BPV) 0.0046 Not felt(I) 0.381 Weak(III)
Chualar Canyon, Santa Cruz, CA, USA (BK.SCZ) 0.0043 Not felt(I) 0.105 Weak(II)
Topo Valley (NC.BTV) 0.0036 Not felt(I) 0.142 Weak(II)
Salinas Radio Site #2 (NC.BSR) 0.0027 Not felt(I) 0.067 Weak(II)
Juan Fiesta (NC.BJF) 0.0025 Not felt(I) 0.081 Weak(II)
Calera Canyon (NC.BCC) 0.0023 Not felt(I) 0.064 Weak(II)
Monterey #4 (NC.HMOB) 0.0017 Not felt(I) 0.053 Not felt(I)
Lonoak Road 2 (NC.PLOB) 0.0016 Not felt(I) 0.065 Weak(II)
Ponciano Ridge (NC.BPRB) 0.0016 Not felt(I) 0.043 Not felt(I)
Hahn Winery (NC.BHW) 0.0016 Not felt(I) 0.064 Weak(II)
Mercy Hot Springs (NC.BMS) 0.0015 Not felt(I) 0.087 Weak(II)
Palo Escrito (NC.BPE) 0.0014 Not felt(I) 0.029 Not felt(I)
Kalte Canyon (NC.BKC) 0.0013 Not felt(I) 0.049 Not felt(I)
Williams Hill (NC.PWH) 0.0013 Not felt(I) 0.039 Not felt(I)
Babies Gulch, Panoche, CA (BK.BABI) 0.0013 Not felt(I) 0.087 Weak(II)
San Benito Historical Park (NC.HHP) 0.0011 Not felt(I) 0.094 Weak(II)
Bitterwater Creek (NC.PBC) 0.0011 Not felt(I) 0.058 Weak(II)
Lone Tree (NC.HLO) 0.0010 Not felt(I) 0.060 Weak(II)
The Indians Road (NC.BTI) 0.0009 Not felt(I) 0.022 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
Soledad
CA
Weak(II)
Gonzales
CA
Weak(II)
Greenfield
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
Mount Johnson (NC.BJOB) Light(IV)
Panoche Road (NC.BPA) Weak(III)
Big Mountain #3 (NC.BBGB) Weak(III)