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Intensity Lab
III

Max Est. MMI

M3.8 earthquake · shaking intensity by town 4 km SSE of San Ramon, CA

Magnitude3.8
Depth9.1 km
Time 2026-02-02T14:27:00.610000Z UTC: 2026-02-02T14:27:00.610000Z
USGS ID nc75305671
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)
San Ramon
CA 		760 340
Dublin
CA 		760 294
Blackhawk
CA 		760 466

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 -0.29 0.43 0.52
BSSA14 -0.26 0.38 0.46
CY14 -0.30 0.41 0.50
CB14 -0.27 0.39 0.48
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)
San Ramon (NC.CSR) 0.0546 Light(IV) 2.859 Light(IV)
Fire Station 16 (NP.1689) 0.0331 Light(IV) 1.378 Light(IV)
Hayward (CE.58531) 0.0244 Weak(III) 0.419 Weak(III)
San Ramon (CE.57444) 0.0194 Weak(III) 0.719 Weak(III)
Castro Valley (CE.58340) 0.0130 Weak(III) 0.390 Weak(III)
Pleasanton (CE.57452) 0.0113 Weak(III) 0.765 Weak(III)
Fire Station 31 (NP.1690) 0.0076 Weak(III) 0.321 Weak(III)
Round Hill Res (NC.CRH) 0.0070 Weak(III) 0.264 Weak(II)
Lake Chabot (NC.CLCB) 0.0062 Weak(III) 0.252 Weak(II)
San Leandro Hills (NC.CSL) 0.0062 Weak(III) 0.308 Weak(III)
Round Valley Regional Preserve (BK.RVRP) 0.0049 Weak(II) 0.157 Weak(II)
Masonic Home (NP.1739) 0.0035 Weak(II) 0.116 Weak(II)
Fire Station 2 (NP.1691) 0.0034 Weak(II) 0.140 Weak(II)
Pinole Ridge (NC.CPI) 0.0033 Weak(II) 0.110 Weak(II)
Pleasanton FS 1 (NP.1863) 0.0032 Weak(II) 0.197 Weak(II)
Union City FS 2 Alvarado Bl (NP.1802) 0.0031 Weak(II) 0.070 Weak(II)
Forest Fire Station (NP.1688) 0.0030 Weak(II) 0.104 Weak(II)
Niles Canyon (NC.CNI) 0.0029 Weak(II) 0.080 Weak(II)
Fire Station 27 (NP.1858) 0.0027 Weak(II) 0.130 Weak(II)
San Leandro FS 11 (NP.1836) 0.0022 Weak(II) 0.102 Weak(II)
Fire Station 13 (NP.1857) 0.0020 Weak(II) 0.069 Weak(II)
Morgan Territory (NC.CMOB) 0.0020 Weak(II) 0.101 Weak(II)
Garin Park (surface) (NC.CGP) 0.0020 Weak(II) 0.066 Weak(II)
Byron Hot Springs #2 (NC.CBSB) 0.0018 Weak(II) 0.092 Weak(II)
Contra Costa FS 11 Clayton (NP.1846) 0.0017 Weak(II) 0.047 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
San Ramon
CA 		Weak(III)
Dublin
CA 		Weak(III)
Blackhawk
CA 		Weak(III)

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
San Ramon (NC.CSR) Light(IV)
Fire Station 16 (NP.1689) Light(IV)
San Ramon (CE.57444) Weak(III)