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Max Est. MMI

M4.5 earthquake · shaking intensity by town 2 km W of Brawley, CA

Magnitude4.5
Depth15.9 km
Time 2026-05-10T03:39:29.810000Z UTC: 2026-05-10T03:39:29.810000Z
USGS ID ci41460512
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)
Brawley
CA 		760 227
Westmorland
CA 		760 211
Calipatria
CA 		760 218
Imperial
CA 		760 227

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 -0.32 0.41 0.52
BSSA14 -0.06 0.35 0.35
CY14 -0.25 0.41 0.48
CB14 -0.32 0.43 0.53
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)
Airport Hangar (NP.5060) 0.4009 Severe(VIII) 10.533 Strong(VI)
Imperial (CI.IMP) 0.1287 Strong(VI) 3.767 Light(IV)
Calipatria 2 (CI.CLI2) 0.0825 Moderate(V) 4.140 Light(IV)
El Centro Array 5, James Rd (NP.952) 0.0430 Light(IV) 2.085 Light(IV)
Naval Air Facility El Centro (NP.5051) 0.0426 Light(IV) 2.061 Light(IV)
Westmorland (CE.11369) 0.0409 Light(IV) 3.333 Light(IV)
Ocotillo FS 6 (NP.5482) 0.0237 Weak(III) 0.877 Weak(III)
Desert Research Extended Center (CI.DRE) 0.0223 Weak(III) 1.377 Light(IV)
Schaffner Ranch (CI.SNR) 0.0215 Weak(III) 0.858 Weak(III)
Ocotillo Community Park (CI.OCP) 0.0210 Weak(III) 0.714 Weak(III)
El Centro Array 9, Imperial Irrigation District Su (NP.117) 0.0187 Weak(III) 0.880 Weak(III)
Fire Station (NP.5061) 0.0169 Weak(III) 0.613 Weak(III)
El Centro Array 3, Pine School (NP.5057) 0.0166 Weak(III) 0.924 Weak(III)
Cook Ranch 2 (CI.COK2) 0.0163 Weak(III) 0.839 Weak(III)
Salton Sea Wildlife (SSW) (NP.5062) 0.0162 Weak(III) 0.794 Weak(III)
El Centro Array 1, Borchard Ranches (NP.5056) 0.0151 Weak(III) 0.606 Weak(III)
Elmore's Ranch (CI.ERR) 0.0138 Weak(III) 0.550 Weak(III)
El Centro (CI.ELO) 0.0114 Weak(III) 0.619 Weak(III)
Meadows Union School (NP.464) 0.0110 Weak(III) 0.757 Weak(III)
Bonds Corner, Omlin Residence (NP.5054) 0.0091 Weak(III) 0.412 Weak(III)
CA:El Centro;ECA11 McCabe Sch (NP.5058) 0.0087 Weak(III) 0.567 Weak(III)
Sam W. Stewart (CI.SWS) 0.0086 Weak(III) 0.312 Weak(III)
CA:Pine Valley;FS (NP.5491) 0.0073 Weak(III) 0.282 Weak(III)
Niland (CE.11698) 0.0073 Weak(III) 0.374 Weak(III)
Coachella (CI.COA) 0.0072 Weak(III) 0.262 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

4 sites
Location MMI Description
Brawley
CA 		Moderate(V)
Westmorland
CA 		Light(IV)
Calipatria
CA 		Light(IV)
Imperial
CA 		Light(IV)

Seismic Station Observed MMI

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

7 stations
Station MMI Description
Airport Hangar (NP.5060) Strong(VI)
Calipatria 2 (CI.CLI2) Light(IV)
Imperial (CI.IMP) Light(IV)
Westmorland (CE.11369) Light(IV)
Naval Air Facility El Centro (NP.5051) Light(IV)
El Centro Array 5, James Rd (NP.952) Light(IV)
Desert Research Extended Center (CI.DRE) Light(IV)