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III

Max Est. MMI

30 km SSW of Alamo, Nevada

Magnitude4.4
Depth4.0 km
Time 2026-04-29T15:06:13.025000Z UTC: 2026-04-29T15:06:13.025000Z
USGS ID nn00916724
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Ground Shaking Intensities — Interpolated ShakeMap MMI

3 sites
Location MMI Description
Alamo
NV
Weak(III)
Moapa Town
NV
Weak(II)
Caliente
NV
Weak(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 Description
Pahroc Range, Nevada. (GPS 12/04/2000) w84 (NN.PRN) Weak(II)
Indian Springs High School, NV, CEMP (QN.ISHS) Not felt(I)
Sheep Range, Nevada w84gm (NN.SHP) Weak(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 +0.35 0.54 0.64
BSSA14 +0.35 0.53 0.63
CY14 +0.35 0.54 0.64
CB14 +0.35 0.54 0.64
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)
Hell's Gate, California w84 (SN.HEL) 0.0043 Not felt(I) 0.306 Weak(III)
Pahroc Range, Nevada. (GPS 12/04/2000) w84 (NN.PRN) 0.0034 Not felt(I) 0.174 Weak(II)
Santa Clara, Utah (UU.SCUT) 0.0020 Not felt(I) 0.157 Weak(II)
Hyde High School, LLNL/ANSS BB+SM w84 (NN.HYDE) 0.0020 Not felt(I) 0.170 Weak(II)
7433 Soaring Heights Ave, Las Vegas (NN.WTNK) 0.0018 Not felt(I) 0.061 Weak(II)
Las Vegas Fire Station (NN.LV04) 0.0016 Not felt(I) 0.131 Weak(II)
Rachel, NV, USA (NN.S11A) 0.0015 Not felt(I) 0.092 Weak(II)
Sheep Range, Nevada w84gm (NN.SHP) 0.0013 Not felt(I)
Veyo Road, UT (UU.VRUT) 0.0011 Not felt(I) 0.058 Weak(II)
Indian Springs High School, NV, CEMP (QN.ISHS) 0.0010 Not felt(I) 0.048 Not felt(I)
Clark County Firehouse 12; ANSS SM w84gm (NN.CC12) 0.0010 Not felt(I) 0.108 Weak(II)
Twin Springs Ranch, NV, CEMP (QN.TSRA) 0.0009 Not felt(I) 0.048 Not felt(I)
FORGE 1 (UU.FOR1) 0.0009 Not felt(I) 0.010 Not felt(I)
Iron County Adult Education (UU.IAE) 0.0008 Not felt(I) 0.027 Not felt(I)
Furnace Creek (CI.FUR) 0.0008 Not felt(I) 0.097 Weak(II)
Amargosa Valley Town Office, NV, CEMP (QN.AVTO) 0.0007 Not felt(I) 0.088 Weak(II)
Washington County School District (UU.WDO) 0.0007 Not felt(I) 0.034 Not felt(I)
Henderson FS (NN.HF05) 0.0007 Not felt(I) 0.054 Not felt(I)
Pioche, NV, USA - NN reactivation (NN.PIO) 0.0007 Not felt(I) 0.039 Not felt(I)
Pony Springs, Pioche, NV, USA (NN.R12A) 0.0007 Not felt(I) 0.030 Not felt(I)
Las Vegas Fire Station (NN.LV09) 0.0006 Not felt(I) 0.059 Weak(II)
Vocational High School w84gm (NN.VOTK) 0.0006 Not felt(I) 0.048 Not felt(I)
Topopah Spring, Nevada, USA (US.TPNV) 0.0006 Not felt(I) 0.039 Not felt(I)
Grapevine Ranger Station (CI.GRA) 0.0006 Not felt(I) 0.046 Not felt(I)
Sarcobatus Flats, NV, CEMP (QN.SCFL) 0.0005 Not felt(I) 0.049 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.