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Intensity Lab
III

Max Est. MMI

M3.8 earthquake · shaking intensity by town 5 km SSE of San Ramon, CA

Magnitude3.8
Depth8.2 km
Time 2026-02-02T15:27:45.980000Z UTC: 2026-02-02T15:27:45.980000Z
USGS ID nc75305826
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 -0.19 0.36 0.41
BSSA14 -0.17 0.33 0.37
CY14 -0.19 0.34 0.39
CB14 -0.16 0.33 0.37
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)
Hayward (CE.58531) 0.0325 Light(IV) 0.664 Weak(III)
San Ramon (NC.CSR) 0.0301 Light(IV) 2.255 Light(IV)
Fire Station 16 (NP.1689) 0.0241 Weak(III) 1.288 Weak(III)
San Ramon (CE.57444) 0.0224 Weak(III) 1.062 Weak(III)
Pleasanton (CE.57452) 0.0147 Weak(III) 1.084 Weak(III)
Castro Valley (CE.58340) 0.0140 Weak(III) 0.580 Weak(III)
Lake Chabot (NC.CLCB) 0.0132 Weak(III) 0.652 Weak(III)
Hayward (CE.58497) 0.0124 Weak(III) 0.453 Weak(III)
Hayward (CE.58219) 0.0115 Weak(III) 0.340 Weak(III)
Fire Station 31 (NP.1690) 0.0093 Weak(III) 0.446 Weak(III)
San Leandro Hills (NC.CSL) 0.0089 Weak(III) 0.395 Weak(III)
Hayward (CE.58653) 0.0064 Weak(III) 0.222 Weak(II)
Round Hill Res (NC.CRH) 0.0061 Weak(III) 0.279 Weak(III)
Forest Fire Station (NP.1688) 0.0055 Weak(II) 0.234 Weak(II)
Union City FS 2 Alvarado Bl (NP.1802) 0.0048 Weak(II) 0.168 Weak(II)
Garin Park (surface) (NC.CGP) 0.0044 Weak(II) 0.150 Weak(II)
Niles Canyon (NC.CNI) 0.0044 Weak(II) 0.175 Weak(II)
Round Valley Regional Preserve (BK.RVRP) 0.0043 Weak(II) 0.199 Weak(II)
Pleasanton FS 1 (NP.1863) 0.0038 Weak(II) 0.261 Weak(II)
Fire Station 2 (NP.1691) 0.0037 Weak(II) 0.195 Weak(II)
Fire Station 27 (NP.1858) 0.0036 Weak(II) 0.128 Weak(II)
Masonic Home (NP.1739) 0.0031 Weak(II) 0.116 Weak(II)
St. Joseph Seminary (NC.JSJ) 0.0024 Weak(II) 0.075 Weak(II)
Fire Station 13 (NP.1857) 0.0023 Weak(II) 0.109 Weak(II)
San Leandro FS 11 (NP.1836) 0.0023 Weak(II) 0.131 Weak(II)
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.

4 stations
Station MMI Description
San Ramon (NC.CSR) Light(IV)
Fire Station 16 (NP.1689) Light(IV)
San Ramon (CE.57444) Light(IV)
Pleasanton (CE.57452) Light(IV)