California earthquakes

M2.8 earthquake 6 km W of Cobb, California

A magnitude 2.8 earthquake struck 6 km W of Cobb, California on Mon, Apr 20, 1987, 2:58 PM PDT (21:58 UTC), 2 km (1 mi) below the surface.

A larger quake followed: M3.5 5 km W of Cobb, California. This one was a foreshock.

Cobb forecastMore in California

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude
2.8 (md), micro
Local time
UTC
1987-04-20 21:58:37 UTC
Depth
1.8 km (1.1 mi), shallow
Epicenter
38.826° N, 122.794° W
Tsunami flag
No
Status
Reviewed by a seismologist

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Location uncertainty
About 0.2 km horizontally, 0.5 km in depth
Magnitude uncertainty
±0.10
Depth from
From location
Station coverage gap
38°
Stations used
35

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 1.5 and up: 177 in the 60 days after this one and 0 in the 30 days before it.

After

  1. 2.55 km SW of Cobb, California · 14384 days ago · -1 km deep · 5 km away
  2. 2.66 km W of Cobb, California · 14384 days ago · 3 km deep · 0 km away
  3. 1.55 km W of Cobb, California · 14384 days ago · 0 km deep · 1 km away
  4. 1.75 km WSW of Hopland, California · 14384 days ago · 5 km deep · 35 km away
  5. 1.97 km WSW of Cobb, California · 14383 days ago · -1 km deep · 3 km away
  6. 3.55 km W of Cobb, California · 14383 days ago · 4 km deep · 1 km away
  7. 2.012 km N of Comptche, California · 14383 days ago · 2 km deep · 93 km away
  8. 3.04 km WNW of Cobb, California · 14382 days ago · 2 km deep · 2 km away
  9. 1.77 km WSW of Calistoga, California · 14382 days ago · 0 km deep · 33 km away
  10. 1.74 km WSW of Cobb, California · 14382 days ago · 0 km deep · 2 km away
  11. 2.29 km WSW of Cobb, California · 14382 days ago · 1 km deep · 4 km away
  12. 2.04 km WNW of Potter Valley, California · 14382 days ago · 0 km deep · 65 km away
  13. 1.65 km SSW of Cobb, California · 14381 days ago · 0 km deep · 6 km away
  14. 1.619 km N of Upper Lake, California · 14381 days ago · 4 km deep · 57 km away
  15. 1.56 km W of Cobb, California · 14381 days ago · 0 km deep · 0 km away
  16. 1.85 km W of Cobb, California · 14381 days ago · 1 km deep · 0 km away
  17. 1.6Northern California · 14381 days ago · 0 km deep · 1 km away
  18. 1.67 km WSW of Cobb, California · 14380 days ago · 3 km deep · 4 km away
  19. 1.918 km NE of Upper Lake, California · 14380 days ago · 8 km deep · 51 km away
  20. 1.74 km SW of Cobb, California · 14380 days ago · -1 km deep · 4 km away
  21. 2.08 km W of Cobb, California · 14379 days ago · 1 km deep · 3 km away
  22. 2.54 km SW of Glen Ellen, California · 14377 days ago · 6 km deep · 58 km away
  23. 1.78 km WNW of Cobb, California · 14377 days ago · 3 km deep · 3 km away
  24. 1.88 km W of Cobb, California · 14377 days ago · 1 km deep · 3 km away
  25. 1.714 km ESE of Hidden Valley Lake, California · 14377 days ago · 1 km deep · 34 km away
  26. 2.220 km NE of Potter Valley, California · 14377 days ago · 7 km deep · 69 km away
  27. 2.14 km SW of Glen Ellen, California · 14377 days ago · 6 km deep · 58 km away
  28. 2.14 km SW of Glen Ellen, California · 14376 days ago · 6 km deep · 58 km away
  29. 2.25 km W of Cobb, California · 14376 days ago · 1 km deep · 1 km away
  30. 1.66 km W of Cobb, California · 14376 days ago · 3 km deep · 0 km away
  31. 2.02 km SE of Larkfield-Wikiup, California · 14376 days ago · 4 km deep · 37 km away
  32. 1.84 km WSW of Cobb, California · 14375 days ago · 1 km deep · 3 km away
  33. 2.05 km WNW of Cobb, California · 14375 days ago · 3 km deep · 2 km away
  34. 1.56 km WSW of Cobb, California · 14375 days ago · 3 km deep · 3 km away
  35. 1.67 km WSW of Cobb, California · 14375 days ago · 4 km deep · 4 km away
  36. 1.62 km SSW of Sutter, California · 14374 days ago · 5 km deep · 96 km away
  37. 1.75 km SW of Cobb, California · 14374 days ago · 2 km deep · 5 km away
  38. 2.65 km WSW of Cobb, California · 14374 days ago · 1 km deep · 2 km away
  39. 1.57 km W of Cobb, California · 14374 days ago · 0 km deep · 2 km away
  40. 1.88 km WSW of Cobb, California · 14373 days ago · 3 km deep · 4 km away
  41. 1.84 km W of Cobb, California · 14373 days ago · -1 km deep · 2 km away
  42. 1.66 km W of Cobb, California · 14373 days ago · 3 km deep · 1 km away
  43. 2.35 km W of Cobb, California · 14373 days ago · 0 km deep · 1 km away
  44. 2.07 km W of Cobb, California · 14373 days ago · 1 km deep · 1 km away
  45. 1.77 km W of Cobb, California · 14372 days ago · 3 km deep · 2 km away
  46. 1.58 km W of Cobb, California · 14372 days ago · -1 km deep · 2 km away
  47. 1.52 km SSE of Calistoga, California · 14372 days ago · 2 km deep · 36 km away
  48. 1.710 km NW of Cobb, California · 14372 days ago · 0 km deep · 6 km away
  49. 2.58 km W of Cobb, California · 14371 days ago · 1 km deep · 2 km away
  50. 1.78 km W of Cobb, California · 14371 days ago · 4 km deep · 3 km away
  51. 2.04 km W of Cobb, California · 14371 days ago · 0 km deep · 2 km away
  52. 2.86 km W of Cobb, California · 14371 days ago · 3 km deep · 1 km away
  53. 1.69 km W of Cobb, California · 14370 days ago · 0 km deep · 3 km away
  54. 1.95 km WSW of Cobb, California · 14370 days ago · 1 km deep · 3 km away
  55. 1.68 km W of Cobb, California · 14370 days ago · -1 km deep · 2 km away
  56. 1.56 km W of Cobb, California · 14370 days ago · 3 km deep · 0 km away
  57. 1.65 km W of Cobb, California · 14370 days ago · -1 km deep · 1 km away
  58. 1.5Northern California · 14369 days ago · 8 km deep · 28 km away
  59. 1.86 km SSE of Cottonwood, California · 14369 days ago · 0 km deep · 78 km away
  60. 1.56 km W of Cobb, California · 14369 days ago · 4 km deep · 0 km away

The first 60 of 177.

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc99058. Read Tue, Sep 22, 2026, 4:04 PM UTC.