Max Est. MMI
55 km W of Petrolia, CA
Ground Shaking Intensities — Interpolated ShakeMap MMI
3 sites| Location | MMI |
|---|---|
|
Ferndale
CA |
II |
|
Fortuna
CA |
I |
|
Rio Dell
CA |
I |
Seismic Station Observed MMI
MMI values are derived directly from observed ground motion measurements at seismic stations and are not spatially interpolated.
| Station | MMI |
|---|---|
| Petrolia, CA USA (BK.PETL) | II |
| Walker Ranch; near Petrolia CA (BK.WLKR) | II |
| Cape Town (NC.KCT) | 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).
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) |
|---|---|---|
|
Ferndale
CA |
760 | 273 |
|
Fortuna
CA |
760 | 418 |
|
Rio Dell
CA |
760 | 468 |
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 — Est. Vs30
GMPEs use the Est. Vs30 values shown in the table above. ShakeMap values are independent of Vs30.
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 |
0.1075 | 0.031 |
|
Fortuna
CA |
0.0902 | 0.025 |
|
Rio Dell
CA |
0.0716 | 0.023 |