Max Est. MMI
27 km W of Petrolia, CA
Ground Shaking Intensities — Interpolated ShakeMap MMI
3 sites| Location | MMI |
|---|---|
|
Ferndale
CA |
II |
|
Rio Dell
CA |
II |
|
Fortuna
CA |
II |
Seismic Station Observed MMI
MMI values are derived directly from observed ground motion measurements at seismic stations and are not spatially interpolated.
| Station | MMI |
|---|---|
| Punta Gorda, Petrolia, CA (BK.PETL) | II |
| Walker Ranch; near Petrolia CA (BK.WLKR) | II |
| Lost Coast Ranch (NP.1725) | 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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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).
Site-Specific Vs30 Values
Shear-wave velocity in the upper 30 m, used for GMPE predictions.
| Location | Default Vs30 (m/s) | Site-Specific Vs30 (m/s) |
|---|---|---|
|
Ferndale
CA |
760 | 273 |
|
Rio Dell
CA |
760 | 468 |
|
Fortuna
CA |
760 | 418 |
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 — Site-Specific Vs30
GMPEs use the site-specific Vs30 values shown in the table above. ShakeMap values are unchanged.
Peak Ground Motion Values — USGS ShakeMap
PGA and PGV interpolated from the USGS ShakeMap grid for this event. Values reflect ShakeMap's ground motion model, not GMPE estimates.
| Location | PGA (%g) | PGV (cm/s) |
|---|---|---|
|
Ferndale
CA |
0.1386 | 0.035 |
|
Rio Dell
CA |
0.1407 | 0.037 |
|
Fortuna
CA |
0.1111 | 0.029 |