quarry blast · reviewed by a seismologist
M 1.6md
Earthquake near Watsonville, CA
No earthquake was likely felt in Watsonville in the 24 hours to 6:13 am PST (14:13 UTC). The last one was M 2.5, 15 km (9 mi) ESE, at 6:10 am PDT on 26 October 2026, estimated intensity II (weak) in town; 6 felt reports to USGS. Every earthquake near Watsonville
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.6 quarry blast was recorded 13 km (8 mi) east of Watsonville, CA, at 11:20 am PDT on 10 August 2017 (18:20 UTC), less than 1 km deep. 2 people have reported feeling it to USGS.
USGS: Central California
13 km (8 mi) S of Gilroy, CA · 49 km (30 mi) SSE of San Jose, CA
- When
- 11:20 am PDT on 10 August 2017 ()
- Where
- 13 km (8 mi) east of Watsonville, CA · earthquakes near Watsonville
- Magnitude
- M 1.6 (md)
- Depth
- -0.1 km below the surface
- Felt
- 2 reports · strongest reported intensity II
- Nearest
- Santa Clara County, 37 km N
- Nearest mapped fault
- San Andreas fault, 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 3374 days ago
Earthquake alerts for Watsonville, 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 11 km (7 mi) from the epicentre. In Watsonville, 13 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: Aromas, San Juan Bautista, Las Lomas, Pajaro, Interlaken, Gilroy.
USGS catalogues this as quarry blast, not an earthquake.
How big was it?
This earthquake released about 6.8 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.6 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,600,000× the energy of this one
- Around the size people start to feel M 3.0 140× the energy of this one
- This earthquake M 1.6 about 6.8 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 4.2 on 2016-07-19 — about 9,400 times the energy of this one.
Before 2016, the USGS record lists 30 earthquakes of M5 or more within 50 km; the five largest:
- 6.9 The 1989 Loma Prieta, California Earthquake · 29 km NW of this epicentre
- 6.5 Near Morgan Hill, California · 25 km N of this epicentre
- 6.2 Near San Jose, California · 48 km NNW of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 47 km N of this epicentre
- 6.1 Near San Jose, California · 38 km NNW 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 36.8905, -121.6128. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Santa Clara County, CA | 37 km (23 mi) | N | earthquakes near Santa Clara County |
| Santa Cruz County, CA | 38 km (23 mi) | WNW | earthquakes near Santa Cruz County |
| San Benito County, CA | 56 km (35 mi) | ESE | earthquakes near San Benito County |
| Monterey County, CA | 77 km (48 mi) | SSE | earthquakes near Monterey County |
| Merced County, CA | 86 km (53 mi) | ENE | earthquakes near Merced County |
| Alameda County, CA | 88 km (55 mi) | NNW | earthquakes near Alameda County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
34 earthquakes have been recorded within 50 km since this one.
- 1.5 15 km E of Seven Trees, California
- 1.8 5 km ENE of Aromas, California
- 2.3 5 km SW of Gilroy, California
- 1.7 5 km NNE of Tres Pinos, California
- 1.5 19 km SW of Gustine, California
- 1.6 Northern California
- 1.6 19 km SW of Gustine, California
- 2.4 5 km ESE of Interlaken, California
- 1.5 6 km ESE of Prunedale, California
- 2.3 11 km S of Tres Pinos, California
- 1.7 5 km SSW of Tres Pinos, California
- 2.0 2 km S of San Juan Bautista, California
- 1.8 3 km S of San Juan Bautista, California
- 2.6 9 km SSW of Ridgemark, California
- 1.9 10 km SSW of Ridgemark, California
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.