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II

Max Est. MMI

6 km WSW of Hermosa Beach, CA

Magnitude3.6
Depth11.9 km
Time 2026-09-27T15:40:01.580000Z UTC: 2026-09-27T15:40:01.580000Z
USGS ID ci41339927
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)
Hermosa Beach
CA 		760 352
Manhattan Beach
CA 		760 354
Redondo Beach
CA 		760 350

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 +0.16 0.42 0.45
BSSA14 +0.16 0.42 0.45
CY14 +0.15 0.41 0.44
CB14 +0.15 0.41 0.43
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)
Lomita (CE.14831) 0.0186 Weak(III) 0.336 Weak(III)
Baldwin Hills (CI.BHP) 0.0097 Weak(II) 0.215 Weak(II)
Inglewood (CE.14683) 0.0089 Weak(II) 0.188 Weak(II)
West Side (CI.WSS) 0.0060 Not felt(I) 0.205 Weak(II)
State Street (CI.STS) 0.0054 Not felt(I) 0.100 Weak(II)
Rancho Palos Verdes (CI.RPV) 0.0051 Not felt(I) 0.162 Weak(II)
Northridge (CI.NOT) 0.0050 Not felt(I) 0.109 Weak(II)
La Fresa (CI.LAF) 0.0049 Not felt(I) 0.167 Weak(II)
Playa Del Rey (CI.PDR) 0.0045 Not felt(I) 0.182 Weak(II)
Pacific Palisades (CE.24014) 0.0037 Not felt(I) 0.169 Weak(II)
Tarzana (CE.24103) 0.0035 Not felt(I) 0.075 Weak(II)
Carson (CE.14935) 0.0033 Not felt(I) 0.061 Weak(II)
Watts (CI.WTT2) 0.0029 Not felt(I) 0.106 Weak(II)
Hawthorne (CE.14834) 0.0028 Not felt(I) 0.059 Weak(II)
La Cienega (CI.LCG) 0.0026 Not felt(I) 0.090 Weak(II)
Monte Nido Fire Station #67 (NP.5080) 0.0024 Not felt(I) 0.035 Not felt(I)
Santa Monica Field 2 (CI.SMF2) 0.0023 Not felt(I) 0.066 Weak(II)
Rinaldi (CI.RIN) 0.0021 Not felt(I) 0.051 Not felt(I)
5081, Woodland Hills, CA (TCF) (NP.5081) 0.0019 Not felt(I) 0.038 Not felt(I)
Ventura (CE.25340) 0.0016 Not felt(I) 0.054 Not felt(I)
Santa Clara (CI.STC) 0.0014 Not felt(I) 0.038 Not felt(I)
Avalon Canyon (CI.AVC) 0.0013 Not felt(I) 0.025 Not felt(I)
Latigo (CI.LAT) 0.0013 Not felt(I) 0.033 Not felt(I)
Mira Catalina School (CI.MIS) 0.0013 Not felt(I) 0.054 Not felt(I)
Camarillo (CI.CLO) 0.0013 Not felt(I) 0.033 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.

Ground Shaking Intensities — Interpolated ShakeMap MMI

3 sites
Location MMI Description
Hermosa Beach
CA 		Weak(II)
Manhattan Beach
CA 		Weak(II)
Redondo Beach
CA 		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
Rancho Palos Verdes (CI.RPV) Weak(II)
La Fresa (CI.LAF) Weak(II)
Playa Del Rey (CI.PDR) Weak(III)