quarry blast · reviewed by a seismologist
M 1.7md
Earthquake near Bonny Doon, CA
No earthquake was likely felt in Bonny Doon in the 24 hours to 8:07 am PST (16:07 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
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.7 quarry blast was recorded 3 km (2 mi) east-southeast of Bonny Doon, CA, at 12:07 pm PDT on 11 August 2020 (19:07 UTC), less than 1 km deep. 4 people have reported feeling it to USGS.
USGS: 3km ESE of Bonny Doon, CA
10 km (6 mi) NW of Santa Cruz, CA · 41 km (25 mi) SW of San Jose, CA
- When
- 12:07 pm PDT on 11 August 2020 ()
- Where
- 3 km (2 mi) east-southeast of Bonny Doon, CA · earthquakes near Bonny Doon
- Magnitude
- M 1.7 (md)
- Depth
- -0.3 km below the surface
- Felt
- 4 reports · strongest reported intensity III
- Nearest
- Santa Cruz County, 10 km E
- Nearest mapped fault
- Monterey Bay- Tularcitos fault, 8 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 2282 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 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 Bonny Doon, 3 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: Scotts Valley 10 km, intensity II · Santa Cruz 10 km, intensity II · Boulder Creek 11 km, intensity II. Estimated for each town centre; each link is that town's own record.
USGS catalogues this as quarry blast, not an earthquake.
How big was it?
This earthquake released about 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 870,000× the energy of this one
- Around the size people start to feel M 3.0 78× the energy of this one
- This earthquake M 1.7 about 12 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
The largest earthquake within 50 km since 2016 was M 4.0 on 2017-03-31 — about 2,500 times the energy of this one.
Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 22 km E of this epicentre
- 6.5 Near Morgan Hill, California · 44 km ENE of this epicentre
- 6.3 22 km S of Davenport, California · 25 km SSW of this epicentre
- 6.3 16 km SW of Davenport, California · 22 km WSW of this epicentre
- 6.2 Near San Jose, California · 42 km NE 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 37.0272, -122.1233. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Cruz County, CA | 10 km (6 mi) | E | earthquakes near Santa Cruz County |
| Santa Clara County, CA | 44 km (27 mi) | ENE | earthquakes near Santa Clara County |
| San Mateo County, CA | 48 km (30 mi) | NNW | earthquakes near San Mateo County |
| Alameda County, CA | 71 km (44 mi) | NNE | earthquakes near Alameda County |
| Contra Costa County, CA | 100 km (62 mi) | N | earthquakes near Contra Costa County |
| San Benito County, CA | 103 km (64 mi) | ESE | earthquakes near San Benito County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
44 earthquakes have been recorded within 50 km since this one.
- 1.8 2km ESE of Aromas, CA
- 1.8 3km E of Aromas, CA
- 1.7 7km N of Day Valley, CA
- 2.3 6km SSW of Gilroy, CA
- 1.8 2km ENE of Aromas, CA
- 2.3 4km SW of Moss Landing, CA
- 1.7 6km SSW of Gilroy, CA
- 1.6 3km E of Aromas, CA
- 1.8 6km WSW of Gilroy, CA
- 1.7 7km WSW of Gilroy, CA
- 1.7 3km E of Aromas, CA
- 1.7 3km E of Aromas, CA
- 1.5 7km WSW of Gilroy, CA
- 1.8 7km WSW of Gilroy, CA
- 1.7 6km NNE of Corralitos, 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.