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SeismoAtlas

M1.6 earthquake 4 km WNW of Fontana, California, United States

A magnitude 1.6 earthquake struck 4 km WNW of Fontana, California, United States at 02:37 local time (09:37 UTC) on 23 Oct 2026, at a depth of 7 km, according to USGS.

Data: USGS · updated 2026-10-23 21:36 UTC · reviewed

Magnitude
1.6micro
local magnitude (Richter) (ml)
Depth
6.6 km
Status
Reviewed
Origin time
2026-10-23 09:37:49 UTC
Local: 23 Oct 2026, 02:37:49 (America/Los Angeles)
Epicentre
34.098° N, 117.483° W

Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map

Nearby places

Distance and estimated shaking at nearby places
PlaceDistanceEst. shaking
FontanaCalifornia, United States · pop. 212,7044 kmINot felt
BloomingtonCalifornia, United States · pop. 23,8518 kmINot felt
Glen AvonCalifornia, United States · pop. 20,19910 kmINot felt
Rancho CucamongaCalifornia, United States · pop. 175,23610 kmINot felt
RiversideCalifornia, United States · pop. 317,26118 kmINot felt
AnaheimCalifornia, United States · pop. 350,74249 kmINot felt
Santa AnaCalifornia, United States · pop. 310,22753 kmINot felt
IrvineCalifornia, United States · pop. 256,92757 kmINot felt

Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more.

Every agency's solution

Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · CI, which has been reviewed by an analyst.

AgencyMagnitudeDepthEpicentreTime offsetStatus
USGS · CIheadlineSouthern California Seismic Network via U.S. Geological Survey1.6 mlwas 1.66.6 km34.10° N, 117.48° W–Reviewed · 2 revisions

How big was it?

Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.

It released roughly the energy of 4 kg of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 7 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.

M1.6 releases about 7.7× the energy of M1.0, and its waves are about 3.9× taller on a seismogram. Energy: 4 kg of TNT vs 477 g of TNT.

Each square is the energy of one M1.0. Energy from log₁₀E = 1.5M + 4.8.

Aftershocks and nearby activity

120 later earthquakes within 30 km; the largest was M2.2 13 days ago. 30 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M1.6

120 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).

Aftershocks
Time after mainshock (hours)MagnitudeDepth (km)
0.011.37
0.980.87
8.961.3-1
27.740.99
35.471.13
37.000.71
37.520.89
41.020.78
46.480.811
50.880.611
54.651.48
65.851.012
69.540.612
75.661.67
78.041.06
83.101.02
83.421.4-1
85.550.97
86.920.813
86.921.011
88.920.77
93.221.012
106.420.90
112.001.213
126.781.14
127.021.26
127.821.34
127.880.85
129.481.15
130.021.15
130.061.85
130.191.14
132.790.85
133.101.07
133.111.34
133.322.05
133.621.0-1
133.801.33
136.660.614
136.730.94
136.941.14
137.550.84
139.080.83
152.881.40
155.590.94
160.442.24
160.580.94
160.811.37
161.632.26
161.641.37
161.651.04
161.670.94
162.060.94
162.061.23
163.341.36
163.351.87
164.080.65
164.350.73
164.440.68
165.400.54
165.740.96
165.741.06
165.750.74
166.740.84
166.981.24
167.120.93
167.340.75
167.350.75
167.380.54
167.790.96
167.801.65
167.851.06
168.940.85
170.680.74
170.681.14
175.001.010
177.400.90
178.510.97
181.631.04
184.140.94
184.351.14
189.110.913
191.251.09
194.900.76
195.211.25
195.240.95
200.042.16
204.451.111
208.001.04
209.250.65
217.400.316
218.330.75
231.931.19
285.190.713
285.230.714
294.301.24
299.881.10
309.690.716
321.901.80
329.130.914
329.140.413
333.580.617
334.631.04
334.981.113
341.420.97
346.701.2-1
348.071.40
348.161.316
355.411.513
357.381.017
358.211.016
359.741.16
359.760.915
390.011.011
403.240.87
429.471.113
442.021.08
474.961.110
484.741.69
491.680.91
  1. 2.2Near Loma Linda, California, United States10-30 02:04
  2. 2.2Near Loma Linda, California, United States10-30 03:15
  3. 2.1Near Loma Linda, California, United States10-31 17:40
  4. 2.0Near Loma Linda, California, United States10-28 22:56
  5. 1.8Near Loma Linda, California, United States10-28 19:41
  6. 1.8Near Loma Linda, California, United States10-30 04:58
  7. 1.8Near El Cerrito Corona, California, United States11-05 19:31
  8. 1.64 km W of Fontana, California, United States10-26 13:17
  9. 1.6Near Loma Linda, California, United States10-30 09:25
  10. 1.64 km N of Jurupa Valley, California, United States11-12 14:22
  11. 1.5Near Loma Linda, California, United States11-07 05:02
  12. 1.4Near El Cerrito Corona, California, United States10-29 18:30
  13. 1.43 km ENE of El Cerrito Corona, California, United States10-26 21:03
  14. 1.46 km NW of Jurupa Valley, California, United States10-25 16:16
  15. 1.4Near Home Gardens, California, United States11-06 21:41
  16. 1.34 km SW of Redlands, California, United States10-28 23:25
  17. 1.35 km SW of Redlands, California, United States10-28 22:44
  18. 1.37 km NNW of Eastvale, California, United States10-30 02:26
  19. 1.3Near El Cerrito Corona, California, United States10-23 18:35
  20. 1.36 km SSW of Redlands, California, United States11-06 21:47
  21. 1.3Near Loma Linda, California, United States10-30 03:16
  22. 1.3Near Loma Linda, California, United States10-30 04:58
  23. 1.34 km SW of Redlands, California, United States10-28 17:26
  24. 1.34 km WNW of Fontana, California, United States10-23 09:38
  25. 1.2Near Home Gardens, California, United States11-06 20:20

Did you feel it?

Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.

Reports close 14 days after an earthquake.

Reports on SeismoAtlas

No reports yet.

Event id ci41350959. First recorded here 23 Oct 2026, 09:40:41 UTC. Solutions: USGS · CI (usgs:ci41350959). Cite as: SeismoAtlas, “M1.6 earthquake 4 km WNW of Fontana, California, United States”, https://seismoatlas.com/earthquake/ci41350959-m1-6-earthquake-4-km-wnw-of-fontana-california-united-states, data from USGS.

JSON: /api/v1/events/ci41350959. SeismoAtlas is not an official warning service.