California earthquakes

M2.1 earthquake 3 km SSW of Ridgemark, California

A magnitude 2.1 earthquake struck 3 km SSW of Ridgemark, California on Sat, May 20, 1978, 10:09 AM PDT (17:09 UTC), 9 km (6 mi) below the surface.

A larger quake followed: M4.2 12 km S of Davenport, California. This one was a foreshock.

Ridgemark 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
2.1 (md), micro
Local time
UTC
1978-05-20 17:09:39 UTC
Depth
9.0 km (5.6 mi), shallow
Epicenter
36.778° N, 121.379° 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 0.3 km horizontally, 0.8 km in depth
Magnitude uncertainty
±0.12
Depth from
From location
Station coverage gap
53°
Stations used
30

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 144 in the 60 days after this one and 78 in the 30 days before it.

After

  1. 1.85 km ESE of East Foothills, California · 17663 days ago · 0 km deep · 74 km away
  2. 1.95 km E of East Foothills, California · 17663 days ago · 0 km deep · 74 km away
  3. 1.820 km SSE of Tres Pinos, California · 17663 days ago · 5 km deep · 22 km away
  4. 1.68 km NE of Tres Pinos, California · 17663 days ago · 8 km deep · 13 km away
  5. 1.77 km NE of Tres Pinos, California · 17662 days ago · 8 km deep · 12 km away
  6. 3.514 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 16 km away
  7. 3.114 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 15 km away
  8. 1.614 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 16 km away
  9. 1.914 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 15 km away
  10. 1.614 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 16 km away
  11. 1.714 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 15 km away
  12. 1.914 km SSE of Tres Pinos, California · 17661 days ago · 3 km deep · 15 km away
  13. 2.314 km SSE of Tres Pinos, California · 17660 days ago · 3 km deep · 15 km away
  14. 1.94 km E of East Foothills, California · 17660 days ago · 0 km deep · 76 km away
  15. 1.813 km SSE of Tres Pinos, California · 17660 days ago · 3 km deep · 15 km away
  16. 2.214 km SSE of Tres Pinos, California · 17660 days ago · 4 km deep · 15 km away
  17. 1.58 km E of Gilroy, California · 17660 days ago · 4 km deep · 27 km away
  18. 2.013 km SSE of Tres Pinos, California · 17660 days ago · 4 km deep · 15 km away
  19. 1.614 km SSE of Tres Pinos, California · 17659 days ago · 3 km deep · 15 km away
  20. 2.09 km NE of San Juan Bautista, California · 17659 days ago · 4 km deep · 17 km away
  21. 1.814 km SSE of Tres Pinos, California · 17659 days ago · 3 km deep · 16 km away
  22. 2.06 km E of East Foothills, California · 17658 days ago · 0 km deep · 74 km away
  23. 1.51 km WNW of Hollister, California · 17658 days ago · 4 km deep · 10 km away
  24. 1.64 km E of East Foothills, California · 17658 days ago · 0 km deep · 75 km away
  25. 1.713 km SSE of Tres Pinos, California · 17658 days ago · 4 km deep · 15 km away
  26. 1.614 km SSE of Tres Pinos, California · 17658 days ago · 3 km deep · 15 km away
  27. 1.826 km NE of Greenfield, California · 17658 days ago · 6 km deep · 44 km away
  28. 2.422 km ENE of Soledad, California · 17657 days ago · 2 km deep · 36 km away
  29. 1.814 km SSE of Tres Pinos, California · 17657 days ago · 3 km deep · 16 km away
  30. 1.713 km SSE of Tres Pinos, California · 17656 days ago · 3 km deep · 15 km away
  31. 2.435 km W of Three Rocks, California · 17656 days ago · 3 km deep · 59 km away
  32. 1.514 km SSE of Tres Pinos, California · 17656 days ago · 3 km deep · 15 km away
  33. 2.8Central California · 17656 days ago · 3 km deep · 15 km away
  34. 2.113 km SSE of Tres Pinos, California · 17656 days ago · 4 km deep · 15 km away
  35. 1.713 km SSE of Tres Pinos, California · 17656 days ago · 4 km deep · 15 km away
  36. 2.26 km ESE of Sunol, California · 17655 days ago · 11 km deep · 97 km away
  37. 2.015 km SSE of Tres Pinos, California · 17655 days ago · 4 km deep · 16 km away
  38. 1.815 km SSE of Tres Pinos, California · 17655 days ago · 4 km deep · 16 km away
  39. 1.916 km SSE of Tres Pinos, California · 17655 days ago · 5 km deep · 17 km away
  40. 2.6Central California · 17655 days ago · 9 km deep · 36 km away
  41. 1.6Northern California · 17655 days ago · 1 km deep · 63 km away
  42. 3.6Central California · 17654 days ago · 9 km deep · 19 km away
  43. 2.221 km NNE of Soledad, California · 17653 days ago · 8 km deep · 26 km away
  44. 2.415 km SSE of Tres Pinos, California · 17652 days ago · 3 km deep · 16 km away
  45. 1.86 km N of Greenfield, California · 17652 days ago · 3 km deep · 46 km away
  46. 3.114 km SSE of Tres Pinos, California · 17651 days ago · 3 km deep · 16 km away
  47. 2.314 km SSE of Tres Pinos, California · 17651 days ago · 4 km deep · 16 km away
  48. 2.214 km SSE of Tres Pinos, California · 17651 days ago · 4 km deep · 16 km away
  49. 2.316 km SSE of Tres Pinos, California · 17650 days ago · 5 km deep · 17 km away
  50. 1.924 km NE of Greenfield, California · 17650 days ago · 5 km deep · 44 km away
  51. 2.523 km NE of King City, California · 17650 days ago · 8 km deep · 58 km away
  52. 1.613 km SSE of Tres Pinos, California · 17650 days ago · 4 km deep · 15 km away
  53. 2.027 km NE of Soledad, California · 17649 days ago · 9 km deep · 36 km away
  54. 2.113 km S of Tres Pinos, California · 17649 days ago · 3 km deep · 14 km away
  55. 2.731 km ENE of San Lucas, California · 17649 days ago · 9 km deep · 83 km away
  56. 1.78 km SE of San Juan Bautista, California · 17648 days ago · 4 km deep · 10 km away
  57. 1.85 km WSW of Gilroy, California · 17646 days ago · 7 km deep · 32 km away
  58. 1.814 km SSE of Tres Pinos, California · 17646 days ago · 3 km deep · 15 km away
  59. 1.622 km NE of San Lucas, California · 17646 days ago · 6 km deep · 71 km away
  60. 1.74 km ESE of Aromas, California · 17645 days ago · 6 km deep · 22 km away

The first 60 of 144.

Before

  1. 1.912 km ESE of East Foothills, California · 17663 days ago · 6 km deep · 67 km away
  2. 1.621 km NE of Soledad, California · 17663 days ago · 7 km deep · 32 km away
  3. 1.922 km NNE of Soledad, California · 17664 days ago · 8 km deep · 24 km away
  4. 1.76 km ESE of East Foothills, California · 17664 days ago · 0 km deep · 73 km away
  5. 1.917 km SSE of Tres Pinos, California · 17666 days ago · 4 km deep · 18 km away
  6. 2.08 km NW of Hollister, California · 17666 days ago · 4 km deep · 17 km away
  7. 1.94 km E of East Foothills, California · 17667 days ago · 0 km deep · 75 km away
  8. 1.85 km ESE of East Foothills, California · 17668 days ago · 0 km deep · 74 km away
  9. 2.08 km NNE of Milpitas, California · 17669 days ago · 4 km deep · 92 km away
  10. 2.15 km E of East Foothills, California · 17669 days ago · 0 km deep · 74 km away
  11. 2.35 km E of East Foothills, California · 17669 days ago · 0 km deep · 74 km away
  12. 2.36 km NE of Ridgemark, California · 17670 days ago · 10 km deep · 10 km away
  13. 2.325 km ENE of Greenfield, California · 17671 days ago · 1 km deep · 52 km away
  14. 1.66 km E of East Foothills, California · 17671 days ago · 0 km deep · 74 km away
  15. 1.55 km ESE of East Foothills, California · 17671 days ago · 2 km deep · 74 km away
  16. 2.15 km E of East Foothills, California · 17672 days ago · 0 km deep · 74 km away
  17. 3.05 km E of East Foothills, California · 17672 days ago · 0 km deep · 75 km away
  18. 2.95 km ESE of East Foothills, California · 17672 days ago · 0 km deep · 74 km away
  19. 1.76 km E of East Foothills, California · 17672 days ago · 0 km deep · 74 km away
  20. 1.75 km E of East Foothills, California · 17672 days ago · 0 km deep · 75 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc1040344. Read Mon, Sep 28, 2026, 8:51 PM UTC.