quarry blast · reviewed by a seismologist
M 1.5ml
Earthquake near Bostonia, CA
No earthquake was likely felt in Bostonia in the 24 hours to 1:04 pm PST (21:04 UTC). The last one was M 4.9, 170 km (105 mi) ESE, at 10:27 am PST on 3 November 2026, estimated intensity II (weak) in town; 321 felt reports to USGS. Every earthquake near Bostonia
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.5 quarry blast was recorded 6 km (3 mi) east-southeast of Bostonia, CA, at 2:00 pm PDT on 15 August 2023 (21:00 UTC), less than 1 km deep.
USGS: 6 km ESE of Bostonia, CA
24 km (15 mi) E of San Diego, CA · 7 km (5 mi) ESE of El Cajon, CA
- When
- 2:00 pm PDT on 15 August 2023 ()
- Where
- 6 km (3 mi) east-southeast of Bostonia, CA · earthquakes near Bostonia
- Magnitude
- M 1.5 (ml)
- Depth
- -0.3 km below the surface
- Felt
- no reports yet
- Nearest
- San Diego County, 29 km NNE
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1185 days ago
Earthquake alerts for Bostonia, CA
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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 10 km (6 mi) from the epicentre. In Bostonia, 6 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: Granite Hills, Crest, Rancho San Diego, Harbison Canyon, Winter Gardens, Jamul.
USGS catalogues this as quarry blast, not an earthquake.
How big was it?
This earthquake released about 6.2 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
- Magna, Utah 2020 M 5.7 1,700,000× the energy of this one
- Around the size people start to feel M 3.0 150× the energy of this one
- This earthquake M 1.5 about 6.2 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 one earthquake of M5 or more within 50 km:
- 5.0 16 km NW of Julian, California · 50 km NNE 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 32.7818, -116.8855. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Diego County, CA | 29 km (18 mi) | NNE | earthquakes near San Diego County |
| Orange County, CA | 129 km (80 mi) | NW | earthquakes near Orange County |
| Riverside County, CA | 134 km (83 mi) | NE | earthquakes near Riverside County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
31 earthquakes have been recorded within 50 km since this one.
- 1.7 4 km NE of Rancho San Diego, CA
- 2.1 14 km SE of Tijuana, B.C., MX
- 1.7 11 km E of Julian, CA
- 1.8 19 km ESE of Tijuana, B.C., MX
- 1.9 10 km ESE of Alpine, CA
- 1.5 5 km NE of Rancho San Diego, CA
- 1.5 6 km NNW of Lakeside, CA
- 1.9 15 km NW of Rosarito, B.C., MX
- 2.1 16 km SW of La Jolla, CA
- 1.5 5 km NE of Rancho San Diego, CA
- 1.8 6 km SSE of Alpine, CA
- 2.4 14 km ENE of Tijuana, B.C., MX
- 1.5 6 km NNW of Lakeside, CA
- 2.4 12 km E of Julian, CA
- 1.6 6 km ESE of Chula Vista, 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.