Intensity Lab
← All events
V

Max Est. MMI

1 km SE of Boulder Creek, CA

Magnitude4.6
Depth10.4 km
Time 2026-04-02T08:41:25.520000Z UTC: 2026-04-02T08:41:25.520000Z
USGS ID nc75337442
ShakeMap View USGS ↗

Ground Shaking Intensities — Interpolated ShakeMap MMI

12 sites
Location MMI Description
Bonny Doon
CA 		Moderate(V)
Ben Lomond
CA 		Moderate(V)
Brookdale
CA 		Moderate(V)
Felton
CA 		Moderate(V)
Boulder Creek
CA 		Moderate(V)
Lompico
CA 		Moderate(V)
Mount Hermon
CA 		Light(IV)
Scotts Valley
CA 		Light(IV)
Lexington Hills
CA 		Light(IV)
Los Gatos
CA 		Light(IV)
Monte Sereno
CA 		Light(IV)
Pasatiempo
CA 		Light(IV)

Shaking Animations

Simulated bowling pin shaking at each city’s intensity level. Videos appear as they finish rendering.

2 sites
Location Type MMI Description Animation
Ben Lomond Mountain Observed data Strong(VI)
Brookdale Simulated Moderate(V)

Seismic Station Observed MMI

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

17 stations
Station MMI Description
Ben Lomond Mountain (NC.JBNB) Strong(VI)
Cotoni-Coast Dairies (NC.JCD) Strong(VI)
UCSC Arboretum (NC.JAR) Light(IV)
Pescadero #2 (NC.JPSB) Light(IV)
Bear Gulch Road #2 (NC.JBG) Light(IV)
Peters Creek (NC.JPE) Light(IV)
Cabrillo College (NC.JCC) Light(IV)
Mountain View FS 3 (NP.1775) Light(IV)
Black Mountain #3 (NC.JBMB) Light(IV)
Bear Creek Rd (NC.JBR) Light(IV)
Scotts Valley (NC.JSV) Light(IV)
Las Palmas Park (NP.1791) Light(IV)
Stanford Telescope (NC.JSFB) Light(IV)
Mountain View FS 2 Cuesta (NP.1830) Light(IV)
FD Fire Training Center (NP.1861) Light(IV)
Westmont H.S. Campbell (NP.1799) Light(IV)
Sunnyvale Rod and Gun Club (NP.1862) Light(IV)

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).

Show ▼

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)
Bonny Doon
CA 		760 613
Ben Lomond
CA 		760 408
Brookdale
CA 		760 370
Felton
CA 		760 413
Boulder Creek
CA 		760 391
Lompico
CA 		760 460
Mount Hermon
CA 		760 409
Scotts Valley
CA 		760 404
Lexington Hills
CA 		760 679
Los Gatos
CA 		760 352
Monte Sereno
CA 		760 471
Pasatiempo
CA 		760 469

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 +0.80 0.82 1.15
BSSA14 +0.88 0.84 1.21
CY14 +0.86 0.83 1.20
CB14 +0.86 0.83 1.20
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)
Ben Lomond Mountain (NC.JBNB) 0.5816 Strong(VI) 9.749 Very Strong(VII)
Cotoni-Coast Dairies (NC.JCD) 0.2001 Moderate(V) 9.132 Very Strong(VII)
UCSC Arboretum (NC.JAR) 0.0843 Moderate(V) 2.869 Moderate(V)
Pescadero #2 (NC.JPSB) 0.0617 Light(IV) 2.277 Moderate(V)
Cabrillo College (NC.JCC) 0.0544 Light(IV) 1.875 Moderate(V)
Scotts Valley (NC.JSV) 0.0534 Light(IV) 1.377 Moderate(V)
Bear Creek Rd (NC.JBR) 0.0428 Light(IV) 1.526 Moderate(V)
Bear Gulch Road #2 (NC.JBG) 0.0421 Light(IV) 2.094 Moderate(V)
Peninsula Open Space; Pescadero, CA (BK.PESC) 0.0417 Light(IV) 1.045 Light(IV)
Peters Creek (NC.JPE) 0.0341 Light(IV) 1.882 Moderate(V)
Filoli Center (NP.1752) 0.0310 Light(IV) 0.985 Light(IV)
Black Mountain #3 (NC.JBMB) 0.0309 Light(IV) 1.520 Moderate(V)
Sunnyvale Rod and Gun Club (NP.1862) 0.0277 Light(IV) 1.343 Light(IV)
Mountain View FS 3 (NP.1775) 0.0263 Weak(III) 1.569 Moderate(V)
St. Joseph Seminary (NC.JSJ) 0.0248 Weak(III) 0.956 Light(IV)
Stanford Telescope (NC.JSFB) 0.0234 Weak(III) 1.326 Light(IV)
Addison School (NP.1853) 0.0207 Weak(III) 1.100 Light(IV)
Mount Umunhum (BK.UMUN) 0.0203 Weak(III) 0.539 Weak(III)
Saratoga Golf Course (NC.JSGB) 0.0201 Weak(III) 1.146 Light(IV)
St Josephs Hill (NC.JJO) 0.0187 Weak(III) 0.986 Light(IV)
Fire Station 27 (NP.1858) 0.0183 Weak(III) 0.736 Light(IV)
Foothills Park (NC.JFP) 0.0182 Weak(III) 0.770 Light(IV)
Las Palmas Park (NP.1791) 0.0172 Weak(III) 1.253 Light(IV)
Cahill Ridge (NC.JCH) 0.0170 Weak(III) 0.786 Light(IV)
Jasper Ridge Ecological Reserve (BK.JASP) 0.0164 Weak(III) 0.937 Light(IV)
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.