quarry blast · reviewed by a seismologist
M 1.5md
Earthquake near Loyola, CA
No earthquake was likely felt in Loyola in the 24 hours to 8:08 am PST (16:08 UTC). The last one was M 2.0, 5 km (3 mi) SSE, at 9:23 am PST on 10 November 2026, estimated intensity II (weak) in town; 4 felt reports to USGS. Every earthquake near Loyola
No: USGS classifies this as a quarry blast, not an earthquake. A magnitude 1.5 quarry blast was recorded 3 km (2 mi) south of Loyola, CA, at 12:20 pm PDT on 30 October 2018 (19:20 UTC), less than 1 km deep.
USGS: 3km S of Loyola, CA
26 km (16 mi) W of San Jose, CA · 5 km (3 mi) W of Cupertino, CA
- When
- 12:20 pm PDT on 30 October 2018 ()
- Where
- 3 km (2 mi) south of Loyola, CA · earthquakes near Loyola
- Magnitude
- M 1.5 (md)
- Depth
- -0.3 km below the surface
- Felt
- no reports yet
- Nearest
- San Mateo County, 26 km WNW
- Nearest mapped fault
- Monte Vista-Shannon 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 2934 days ago
Earthquake alerts for Loyola, CA
Get a notification in this browser when USGS records an earthquake near Loyola, 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 10 km (6 mi) from the epicentre. In Loyola, 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: Cupertino 7 km, intensity II · Los Altos 7 km, intensity II · Mountain View 7 km, intensity II · Sunnyvale 8 km, intensity II · Saratoga 10 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 5.4 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 2,800,000× the energy of this one
- Magna, Utah 2020 M 5.7 2,000,000× the energy of this one
- Around the size people start to feel M 3.0 180× the energy of this one
- This earthquake M 1.5 about 5.4 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 4.1 on 2017-10-10 — about 7,700 times the energy of this one.
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 · 38 km SSE of this epicentre
- 6.5 Near Morgan Hill, California · 48 km ESE of this epicentre
- 6.3 16 km SW of Davenport, California · 49 km SSW of this epicentre
- 6.2 Near San Jose, California · 27 km E of this epicentre
- 6.2 The 1984 Morgan Hill, California Earthquake · 38 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 37.3252, -122.1058. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| San Mateo County, CA | 26 km (16 mi) | WNW | earthquakes near San Mateo County |
| Santa Cruz County, CA | 36 km (22 mi) | SSE | earthquakes near Santa Cruz County |
| Santa Clara County, CA | 39 km (24 mi) | ESE | earthquakes near Santa Clara County |
| Alameda County, CA | 40 km (25 mi) | NNE | earthquakes near Alameda County |
| Contra Costa County, CA | 67 km (42 mi) | NNE | earthquakes near Contra Costa County |
| San Francisco County, CA | 93 km (58 mi) | WNW | earthquakes near San Francisco County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
49 earthquakes have been recorded within 50 km since this one.
- 2.6 9km ENE of Milpitas, CA
- 1.5 22km ENE of Alum Rock, CA
- 2.0 15km E of Seven Trees, CA
- 1.8 9km NE of Milpitas, CA
- 1.5 3km S of Loyola, CA
- 2.2 10km ESE of Alum Rock, CA
- 1.6 4km S of Loyola, CA
- 1.9 2km NNE of Union City, CA
- 1.6 6km SSE of Sunol, CA
- 2.3 4km SSW of Los Altos Hills, CA
- 1.7 3km S of Loyola, CA
- 2.0 3km NNE of Fairview, CA
- 2.0 2km ENE of Hayward, CA
- 1.6 5km SW of Dublin, CA
- 2.6 2km SSE of Day 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.