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Intensity Lab
IV

Max Est. MMI

M4.2 earthquake · shaking intensity by town 4 km SE of San Ramon, CA

Magnitude4.2
Depth9.6 km
Time 2026-02-02T15:01:13.640000Z UTC: 2026-02-02T15:01:13.640000Z
USGS ID nc75305736
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 -0.17 0.37 0.40
BSSA14 -0.11 0.32 0.34
CY14 -0.14 0.34 0.37
CB14 -0.13 0.34 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)
San Ramon (NC.CSR) 0.2084 Strong(VI) 11.045 Strong(VI)
Fire Station 16 (NP.1689) 0.0568 Light(IV) 2.714 Light(IV)
Fire Station 31 (NP.1690) 0.0226 Weak(III) 1.311 Light(IV)
Round Hill Res (NC.CRH) 0.0222 Weak(III) 1.309 Light(IV)
Round Valley Regional Preserve (BK.RVRP) 0.0211 Weak(III) 0.666 Weak(III)
Lake Chabot (NC.CLCB) 0.0187 Weak(III) 0.979 Weak(III)
San Leandro Hills (NC.CSL) 0.0116 Weak(III) 0.953 Weak(III)
Fire Station 13 (NP.1857) 0.0098 Weak(III) 0.544 Weak(III)
Morgan Territory (NC.CMOB) 0.0097 Weak(III) 0.358 Weak(III)
Fire Station 2 (NP.1691) 0.0080 Weak(III) 0.450 Weak(III)
Union City FS 2 Alvarado Bl (NP.1802) 0.0080 Weak(III) 0.303 Weak(III)
Masonic Home (NP.1739) 0.0068 Weak(III) 0.277 Weak(III)
Brushy Peak (NC.CBP) 0.0066 Weak(III) 0.218 Weak(II)
Mills College #2 (NC.CMC) 0.0066 Weak(III) 0.246 Weak(II)
LBL Building 88, Berkeley, CA, USA (BK.BL88) 0.0066 Weak(III) 0.346 Weak(III)
FD Fire Training Center (NP.1861) 0.0064 Weak(III) 0.439 Weak(III)
Pinole Ridge (NC.CPI) 0.0059 Weak(III) 0.231 Weak(II)
Contra Costa FS 11 Clayton (NP.1846) 0.0058 Weak(III) 0.265 Weak(II)
Bollinger Canyon Rd (NC.CBR) 0.0057 Weak(II) 0.313 Weak(III)
Fire Station 27 (NP.1858) 0.0054 Weak(II) 0.329 Weak(III)
Pleasanton FS 1 (NP.1863) 0.0053 Weak(II) 0.478 Weak(III)
Forest Fire Station (NP.1688) 0.0052 Weak(II) 0.287 Weak(III)
Coyote Point (NC.JCPB) 0.0052 Weak(II) 0.154 Weak(II)
Garin Park (surface) (NC.CGP) 0.0050 Weak(II) 0.311 Weak(III)
Niles Canyon (NC.CNI) 0.0050 Weak(II) 0.309 Weak(III)
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 		Light(IV)
Dublin
CA 		Light(IV)
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) Strong(VI)
Fire Station 16 (NP.1689) Light(IV)
Round Hill Res (NC.CRH) Light(IV)
Fire Station 31 (NP.1690) Light(IV)