Earthquake · reviewed by a seismologist
M 2.5md
Earthquake near Bonny Doon, CA
No earthquake was likely felt in Bonny Doon in the 24 hours to 1:02 pm PST (21:02 UTC). The last one was M 3.8, 79 km (49 mi) N, at 8:30 am PDT on 13 August 2026, estimated intensity II (weak) in town; 7,876 felt reports to USGS. Every earthquake near Bonny Doon
This page: a magnitude 2.5 earthquake was recorded 16 km (10 mi) south-southwest of Bonny Doon, CA, at 12:54 pm PDT on 9 October 2021 (19:54 UTC), 5.1 km deep. 10 people have reported feeling it to USGS.
USGS: 16km SSW of Bonny Doon, CA
56 km (35 mi) SW of San Jose, CA · 18 km (11 mi) WSW of Santa Cruz, CA
- When
- 12:54 pm PDT on 9 October 2021 ()
- Where
- 16 km (10 mi) south-southwest of Bonny Doon, CA · earthquakes near Bonny Doon
- Magnitude
- M 2.5 (md)
- Depth
- 5.1 km below the surface
- Felt
- 10 reports · strongest reported intensity II
- Nearest
- Santa Cruz County, 22 km ENE
- Nearest mapped fault
- San Gregorio 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 1790 days ago
Earthquake alerts for Bonny Doon, CA
Get a notification in this browser when USGS records an earthquake near Bonny Doon, CA. No account or email needed.
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 small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.
At this magnitude and depth, people at rest would likely notice it out to about 22 km (14 mi) from the epicentre. In Bonny Doon, 16 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: Santa Cruz 18 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 190 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 80,000× the energy of this one
- Magna, Utah 2020 M 5.7 57,000× the energy of this one
- Around the size people start to feel M 3.0 5.1× the energy of this one
- This earthquake M 2.5 about 190 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 19 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 33 km ENE of this epicentre
- 6.3 22 km S of Davenport, California · 11 km S of this epicentre
- 6.3 16 km SW of Davenport, California · 11 km W of this epicentre
- 6.1 Near San Jose, California · 49 km NE of this epicentre
- 5.8 Near Watsonville, California · 46 km E 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 36.9082, -122.2165. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Cruz County, CA | 22 km (14 mi) | ENE | earthquakes near Santa Cruz County |
| San Mateo County, CA | 58 km (36 mi) | NNW | earthquakes near San Mateo County |
| Santa Clara County, CA | 58 km (36 mi) | NE | earthquakes near Santa Clara County |
| Alameda County, CA | 86 km (54 mi) | NNE | earthquakes near Alameda County |
| San Benito County, CA | 106 km (66 mi) | ESE | earthquakes near San Benito County |
| Monterey County, CA | 110 km (68 mi) | SE | earthquakes near Monterey County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
38 earthquakes have been recorded within 50 km since this one.
- 1.8 6km SSE of Portola Valley, CA
- 2.0 6km SSE of Portola Valley, CA
- 2.1 6km SSE of Portola Valley, CA
- 1.9 6km SSE of Portola Valley, CA
- 1.7 6km SSE of Portola Valley, CA
- 1.5 14km WSW of Portola Valley, CA
- 2.4 13km WSW of Santa Cruz, CA
- 1.6 3km SSW of Monte Sereno, CA
- 1.8 6km SSE of Portola Valley, CA
- 1.9 6km SSE of Portola Valley, CA
- 1.9 6km SSE of Portola Valley, CA
- 1.7 7km SSE of Portola Valley, CA
- 1.8 6km SSE of Portola Valley, CA
- 1.6 5km NNW of Aromas, CA
- 2.0 6km SSE of Portola Valley, 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.