Earthquake · reviewed by a seismologist
M 1.8md
Earthquake near Arroyo Grande, CA
No earthquake was likely felt in Arroyo Grande in the 24 hours to 12:39 am PST (08:39 UTC). The last one was M 2.3, 7 km (5 mi) NNW, at 6:27 pm PST on 14 December 2025, estimated intensity II (weak) in town; 25 felt reports to USGS. Every earthquake near Arroyo Grande
This page: a magnitude 1.8 earthquake was recorded 15 km (9 mi) north-northeast of Arroyo Grande, CA, at 2:04 am PDT on 12 September 2024 (09:04 UTC), 5.2 km deep.
USGS: 15 km NE of Arroyo Grande, CA
34 km (21 mi) N of Santa Maria, CA
- When
- 2:04 am PDT on 12 September 2024 ()
- Where
- 15 km (9 mi) north-northeast of Arroyo Grande, CA · earthquakes near Arroyo Grande
- Magnitude
- M 1.8 (md)
- Depth
- 5.2 km below the surface
- Felt
- no reports yet
- Nearest
- San Luis Obispo County, 18 km NNE
- Nearest mapped fault
- Los Osos fault, 7 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 791 days ago
Earthquake alerts for Arroyo Grande, 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 13 km (8 mi) from the epicentre. In Arroyo Grande, 15 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.
Earthquakes near other towns within 30 km: San Luis Obispo, Pismo Beach, Grover Beach, Oceano, Santa Margarita, Nipomo.
How big was it?
This earthquake released about 16 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 930,000× the energy of this one
- Magna, Utah 2020 M 5.7 660,000× the energy of this one
- Around the size people start to feel M 3.0 59× the energy of this one
- This earthquake M 1.8 about 16 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:
- 5.8 Near Los Alamos, California · 49 km S of this epicentre
- 5.0 5 km SSW of Nipomo, California · 26 km S 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 35.2320, -120.4985. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Luis Obispo County, CA | 18 km (11 mi) | NNE | earthquakes near San Luis Obispo County |
| Santa Barbara County, CA | 88 km (55 mi) | SSE | earthquakes near Santa Barbara County |
| Kings County, CA | 112 km (70 mi) | NNE | earthquakes near Kings County |
| Monterey County, CA | 134 km (83 mi) | NNW | earthquakes near Monterey County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
55 earthquakes have been recorded within 50 km since this one.
- 1.9 7 km W of Templeton, CA
- 1.9 7 km W of Templeton, CA
- 2.2 8 km W of Templeton, CA
- 1.8 6 km W of Templeton, CA
- 1.5 8 km W of Templeton, CA
- 1.5 8 km W of Templeton, CA
- 2.8 7 km W of Templeton, CA
- 1.7 7 km W of Templeton, CA
- 2.8 8 km W of Templeton, CA
- 2.2 8 km W of Templeton, CA
- 2.4 8 km W of Templeton, CA
- 2.3 8 km W of Templeton, CA
- 1.8 8 km W of Templeton, CA
- 3.2 8 km W of Templeton, CA
- 1.7 7 km W of Templeton, 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.