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M1.1 earthquake 4 km NW of Calimesa, California, United States

A magnitude 1.1 earthquake struck 4 km NW of Calimesa, California, United States at 21:21 local time (04:21 UTC) on 20 Oct 2026, at a depth of 17 km, according to USGS.

revised from M1.4

Data: USGS · updated 2026-10-21 13:24 UTC · reviewed

Magnitude
1.1micro
local magnitude (Richter) (ml)
revised from 1.4
Depth
16.7 km
Status
Reviewed
Origin time
2026-10-21 04:21:39 UTC
Local: 20 Oct 2026, 21:21:39 (America/Los Angeles)
Epicentre
34.027° N, 117.094° 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
CalimesaCalifornia, United States · pop. 8,5424 kmINot felt
YucaipaCalifornia, United States · pop. 53,3285 kmINot felt
RedlandsCalifornia, United States · pop. 71,0359 kmINot felt
BeaumontCalifornia, United States · pop. 43,81115 kmINot felt
Loma LindaCalifornia, United States · pop. 24,04515 kmINot felt
RiversideCalifornia, United States · pop. 317,26129 kmINot felt
IrvineCalifornia, United States · pop. 256,92778 kmINot felt
Santa AnaCalifornia, United States · pop. 310,22778 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 Survey1.1 mlwas 1.416.7 km34.03° N, 117.09° 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 587 g 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 17 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.

M1.1 releases about 1.2× the energy of M1.0, and its waves are about 1.1× taller on a seismogram. Energy: 587 g 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

131 later earthquakes within 30 km; the largest was M2.2 14 days ago. 26 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M1.1

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

Aftershocks
Time after mainshock (hours)MagnitudeDepth (km)
12.971.015
26.890.94
27.361.04
27.761.34
29.230.95
29.500.95
30.161.213
37.261.114
37.260.89
41.211.113
48.591.84
48.620.96
49.481.05
49.481.55
50.290.715
52.041.34
65.780.613
78.621.04
81.010.99
87.991.013
88.741.13
90.270.71
93.421.613
99.750.811
100.090.76
104.150.611
120.080.417
122.810.612
126.770.512
129.330.68
130.561.214
136.371.02
140.190.813
140.191.011
143.410.92
146.491.012
175.300.36
180.051.14
180.291.26
181.091.34
181.140.85
181.781.010
182.741.15
183.291.15
183.331.85
183.461.14
186.060.85
186.371.07
186.381.34
186.582.05
187.071.33
189.930.614
190.000.94
190.211.14
190.820.84
192.350.83
206.030.818
208.860.94
213.712.24
213.850.94
214.902.26
214.911.37
214.921.04
214.940.94
215.330.94
215.331.23
216.611.36
216.621.87
217.350.65
217.620.73
217.710.68
218.670.54
219.010.96
219.011.06
219.020.74
220.010.84
220.251.24
220.390.93
220.610.75
220.620.75
220.650.54
221.060.96
221.071.65
221.121.06
222.210.85
223.950.74
223.951.14
231.780.97
234.901.04
243.890.613
248.170.76
248.481.25
248.510.95
248.671.08
253.312.16
260.351.117
261.271.04
262.520.65
270.660.316
271.600.75
286.440.89
293.680.69
305.461.113
314.192.014
314.300.612
327.381.514
338.090.413
338.100.916
338.450.713
338.500.714
344.420.817
362.960.716
369.690.99
383.960.514
386.850.617
387.901.04
401.431.316
408.681.513
410.651.017
411.481.016
413.011.16
413.030.915
438.910.520
451.140.917
474.441.417
475.551.55
485.081.18
485.890.99
501.550.93
528.300.917
530.010.414
  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. 2.07 km WSW of Calimesa, California, United States11-03 06:33
  5. 2.0Near Loma Linda, California, United States10-28 22:56
  6. 1.8Near Loma Linda, California, United States10-28 19:41
  7. 1.8Near Loma Linda, California, United States10-30 04:58
  8. 1.85 km ESE of Loma Linda, California, United States10-23 04:57
  9. 1.6Near Loma Linda, California, United States10-30 09:25
  10. 1.65 km SE of Mentone, California, United States10-25 01:46
  11. 1.56 km NNE of Cherry Valley, California, United States11-09 23:54
  12. 1.54 km ESE of Cherry Valley, California, United States11-03 19:44
  13. 1.5Near Loma Linda, California, United States11-07 05:02
  14. 1.55 km ESE of Loma Linda, California, United States10-23 05:50
  15. 1.4Near Beaumont, California, United States11-09 22:48
  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. 1.35 km SW of Redlands, California, United States10-23 08:24
  19. 1.36 km SSW of Redlands, California, United States11-06 21:47
  20. 1.3Near Loma Linda, California, United States10-30 03:16
  21. 1.3Near Loma Linda, California, United States10-30 04:58
  22. 1.34 km SW of Redlands, California, United States10-28 17:26
  23. 1.35 km ESE of Loma Linda, California, United States10-22 08:07
  24. 1.2Near Loma Linda, California, United States10-30 03:41
  25. 1.26 km SSW of Redlands, California, United States10-22 10:31

Did you feel it?

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

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Reports on SeismoAtlas

No reports yet.

Event id ci41349967. First recorded here 21 Oct 2026, 04:24:23 UTC. Solutions: USGS · CI (usgs:ci41349967). Cite as: SeismoAtlas, “M1.1 earthquake 4 km NW of Calimesa, California, United States”, https://seismoatlas.com/earthquake/ci41349967-m1-1-earthquake-4-km-nw-of-calimesa-california-united-states, data from USGS.

JSON: /api/v1/events/ci41349967. SeismoAtlas is not an official warning service.