Earthquake · reviewed by a seismologist
M 2.3md
Earthquake near Morro Bay, CA
No earthquake was likely felt in Morro Bay in the 24 hours to 8:44 am PST (16:44 UTC). The last one was M 2.1, 14 km (9 mi) NE, at 6:08 am PDT on 21 October 2026, estimated intensity II (weak) in town; 3 felt reports to USGS. Every earthquake near Morro Bay
This page: a magnitude 2.3 earthquake was recorded 11 km (7 mi) west-southwest of Morro Bay, CA, at 9:34 am PDT on 4 September 2021 (16:34 UTC), 9.7 km deep. 2 people have reported feeling it to USGS.
USGS: 11km WSW of Morro Bay, CA
65 km (40 mi) NW of Santa Maria, CA
- When
- 9:34 am PDT on 4 September 2021 ()
- Where
- 11 km (7 mi) west-southwest of Morro Bay, CA · earthquakes near Morro Bay
- Magnitude
- M 2.3 (md)
- Depth
- 9.7 km below the surface
- Felt
- 2 reports · strongest reported intensity I
- Nearest
- San Luis Obispo County, 47 km E
- Nearest mapped fault
- Los Osos fault, under 1 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1889 days ago
Earthquake alerts for Morro Bay, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 17 km (11 mi) from the epicentre. In Morro Bay, 11 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: Los Osos 12 km, intensity II · Cayucos 14 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 82 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
- Magna, Utah 2020 M 5.7 130,000× the energy of this one
- Around the size people start to feel M 3.0 12× the energy of this one
- This earthquake M 2.3 about 82 lb of TNT
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
For this area
No earthquake of M4 or more has been recorded within 50 km since our catalogue begins in 2016.
Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:
- 6.5 10 km NE of San Simeon, California · 42 km NNW of this epicentre
- 5.7 Southwest of Cambria, California · 28 km NW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 35.3350, -120.9642. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Luis Obispo County, CA | 47 km (29 mi) | E | earthquakes near San Luis Obispo County |
| Monterey County, CA | 106 km (66 mi) | NNW | earthquakes near Monterey County |
| Santa Barbara County, CA | 122 km (76 mi) | SE | earthquakes near Santa Barbara County |
| Kings County, CA | 132 km (82 mi) | NE | earthquakes near Kings County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
37 earthquakes have been recorded within 50 km since this one.
- 1.6 5km WSW of Paso Robles, CA
- 1.7 4km WSW of Paso Robles, CA
- 1.6 9km N of Cambria, CA
- 1.9 7km W of Templeton, CA
- 1.7 12km NNE of Cambria, CA
- 1.6 2km SE of Cayucos, CA
- 1.8 15km ENE of San Simeon, CA
- 1.5 7km NNE of San Simeon, CA
- 1.6 8km NE of San Simeon, CA
- 2.2 8km NE of San Simeon, CA
- 2.1 8km NE of San Simeon, CA
- 2.5 8km NE of San Simeon, CA
- 1.6 10km SW of Templeton, CA
- 3.3 8km NE of San Simeon, CA
- 2.0 8km NNE of San Simeon, CA
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.