QuakeIndex

Earthquake · reviewed by a seismologist

M 2.3ml

Earthquake near Norco, CA

No earthquake was likely felt in Norco in the 24 hours to 12:16 am PST (08:16 UTC). The last one was M 1.8, 11 km (7 mi) SSE, at 11:31 am PST on 5 November 2026, estimated intensity II (weak) in town. Every earthquake near Norco

This page: a magnitude 2.3 earthquake was recorded 4 km (2 mi) north of Norco, CA, at 4:45 pm PST on 5 February 2018 (00:45 UTC), 5.0 km deep. 20 people have reported feeling it to USGS.

USGS: 4km N of Norco, CA

in Eastvale, CA · 79 km (49 mi) E of Los Angeles, CA

4:45 pm PST, Feb 5, 2018 · · 5.0 km deep · released about 94 lb of TNT

Every earthquake near Norco Felt it? Tell USGS Check my area
10 km30 km60 km120 km N Orange County 38 kmLos Angeles County 70 km
Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.
When
4:45 pm PST on 5 February 2018 ()
Where
4 km (2 mi) north of Norco, CA · earthquakes near Norco
Magnitude
M 2.3 (ml)
Depth
5.0 km below the surface
Felt
20 reports · strongest reported intensity IV
Nearest
Orange County, 38 km SSW
Nearest mapped fault
Elsinore fault, 14 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 2413 days ago

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 20 km (12 mi) from the epicentre. In Norco, 4 km away, the estimate is intensity III (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: Eastvale in town, intensity III · Norco 4 km, intensity III · Pedley 7 km, intensity II · Corona 10 km, intensity II · Chino 14 km, intensity II · Rubidoux 14 km, intensity II · Riverside 14 km, intensity II · Ontario 14 km, intensity II. Estimated for each town centre; each link is that town's own record.

How big was it?

This earthquake released about 94 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

  1. Mineral, Virginia 2011 M 5.8 160,000× the energy of this one
  2. Magna, Utah 2020 M 5.7 110,000× the energy of this one
  3. Around the size people start to feel M 3.0 10× the energy of this one
  4. This earthquake M 2.3 about 94 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 12 earthquakes of M5 or more within 50 km; the five largest:

  1. 6.2 3 km SE of San Bernardino, California · 30 km ENE of this epicentre
  2. 6.0 The 1910 Lake Elsinore, California Earthquake · 32 km SSE of this epicentre
  3. 5.9 The 1987 Whittier Narrows, California Earthquake · 50 km WNW of this epicentre
  4. 5.5 The 1990 Upland, California Earthquake · 24 km NNW of this epicentre
  5. 5.4 5km S of Chino Hills, CA · 20 km W 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 33.9635, -117.5515. Map © OpenStreetMap contributors.

Nearby places

PlaceDistanceDirection from the epicentre
Orange County, CA 38 km (24 mi) SSW earthquakes near Orange County
Los Angeles County, CA 70 km (44 mi) WNW earthquakes near Los Angeles County
San Diego County, CA 127 km (79 mi) SE earthquakes near San Diego County

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

55 earthquakes have been recorded within 50 km since this one.

  1. 1.5 5km SE of Loma Linda, CA
  2. 1.7 2km NNE of Colton, CA
  3. 3.0 6km NE of Fontana, CA
  4. 2.1 4km ESE of Lytle Creek, CA
  5. 3.2 4km ESE of Lytle Creek, CA
  6. 1.8 4km NNE of Fontana, CA
  7. 1.8 6km SSE of Loma Linda, CA
  8. 1.7 8km SSE of Home Gardens, CA
  9. 1.6 12km NE of Trabuco Canyon, CA
  10. 1.8 1km E of South Whittier, CA
  11. 1.6 8km N of Fontana, CA
  12. 2.5 2km NE of Redlands, CA
  13. 1.9 2km NE of Redlands, CA
  14. 1.8 8km ESE of Wrightwood, CA
  15. 1.6 2km NE of Redlands, 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

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.