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III

Max Est. MMI

26 km SSW of Alamo, Nevada

Magnitude4.7
Depth6.5 km
Time 2026-04-29T15:06:12.116000Z UTC: 2026-04-29T15:06:12.116000Z
USGS ID nn00916724
ShakeMap View USGS ↗

Ground Shaking Intensities — Interpolated ShakeMap MMI

3 sites
Location MMI
Alamo
NV 		III
Moapa Town
NV 		II
Caliente
NV 		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
Pahroc Range, Nevada. (GPS 12/04/2000) w84 (NN.PRN) III
Rachel, NV, USA - NN reactivation (NN.S11A) II
Sheep Range, Nevada w84gm (NN.SHP) II

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)
Alamo
NV 		760 296
Moapa Town
NV 		760 374
Caliente
NV 		760 560

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 +0.23 0.43 0.48
BSSA14 +0.23 0.44 0.49
CY14 +0.25 0.46 0.51
CB14 +0.25 0.46 0.51
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)
Pahroc Range, Nevada. (GPS 12/04/2000) w84 (NN.PRN) 0.0034 I 0.174 III
Santa Clara, Utah (UU.SCUT) 0.0020 I 0.157 III
Rachel, NV, USA - NN reactivation (NN.S11A) 0.0015 I 0.092 II
Sheep Range, Nevada w84gm (NN.SHP) 0.0013 I — —
Veyo Road, UT (UU.VRUT) 0.0011 I 0.058 II
FORGE 1 (UU.FOR1) 0.0009 I 0.010 I
Iron County Adult Education (UU.IAE) 0.0008 I 0.027 II
Washington County School District (UU.WDO) 0.0007 I 0.034 II
Pioche, NV, USA - NN reactivation (NN.PIO) 0.0007 I 0.039 II
Topopah Spring, Nevada, USA (US.TPNV) 0.0006 I 0.039 II
Milford High School (UU.MHS2) 0.0004 I 0.028 II
St. George Fire Station 4 (UU.SGSU) 0.0003 I 0.024 I
Zion National Park, UT (UU.ZNPU) 0.0003 I 0.019 I
Mountain Pass (CI.MTP) 0.0002 I 0.015 I
Hurricane High School, Utah (UU.HHS) 0.0002 I 0.019 I
Greenwater Valley, CA. (GPS 03/05/2015) w84gm (NN.GWY) 0.0002 I 0.021 I
Shurtz Canyon (UU.SZCU) 0.0002 I 0.009 I
Willow Creek Ranch, Ely, NV, USA - NN reactivation (NN.Q12A) 0.0002 I 0.013 I
Little Creek Mountain, UT (UU.LCMT) 0.0002 I 0.008 I
FORGE 8 (UU.FOR8) 0.0001 I 0.008 I
Cedar City Park, Utah (UU.CCPU) 0.0001 I 0.010 I
Pine Springs, UT (UU.PSUT) 0.0001 I 0.008 I
FORGE 6 (UU.FOR6) 0.0001 I 0.010 I
FORU - Temp Station (UU.FORU) 0.0001 I 0.007 I
Troy Canyon, Currant, NV, USA (NN.R11B) 0.0001 I 0.006 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.