California earthquakes

M1.6 earthquake 6 km NE of Ridgemark, California

A magnitude 1.6 earthquake struck 6 km NE of Ridgemark, California on Thu, Dec 17, 1987, 6:53 PM PST (02:53 UTC), 5 km (3 mi) below the surface.

A larger quake followed: M1.8 23 km NE of San Ardo, 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
1.6 (md), micro
Local time
UTC
1987-12-18 02:53:43 UTC
Depth
5.0 km (3.1 mi), shallow
Epicenter
36.849° N, 121.311° 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 0.1 km horizontally, 0.4 km in depth
Magnitude uncertainty
±0.15
Depth from
From location
Station coverage gap
54°
Stations used
38

Nearest places

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

Nearby

Within 100 km, magnitude 1.5 and up: 168 in the 60 days after this one and 10 in the 30 days before it.

After

  1. 1.823 km NE of San Ardo, California · 14159 days ago · 3 km deep · 88 km away
  2. 2.411 km SSE of Livermore, California · 14159 days ago · 5 km deep · 90 km away
  3. 2.6Northern California · 14158 days ago · 5 km deep · 90 km away
  4. 3.09 km SW of Tres Pinos, CA · 14158 days ago · 2 km deep · 14 km away
  5. 1.824 km ENE of Soledad, California · 14157 days ago · 2 km deep · 44 km away
  6. 2.022 km ENE of San Lucas, California · 14157 days ago · 9 km deep · 81 km away
  7. 1.5Central California · 14157 days ago · 5 km deep · 3 km away
  8. 1.925 km ENE of Greenfield, California · 14155 days ago · -1 km deep · 52 km away
  9. 2.10 km NNE of Ladera, California · 14155 days ago · 5 km deep · 100 km away
  10. 2.026 km SW of Firebaugh, California · 14155 days ago · 5 km deep · 58 km away
  11. 1.926 km SW of Firebaugh, California · 14155 days ago · 4 km deep · 59 km away
  12. 1.926 km SW of Firebaugh, California · 14155 days ago · 3 km deep · 58 km away
  13. 1.726 km SW of Firebaugh, California · 14155 days ago · 4 km deep · 58 km away
  14. 1.526 km SW of Firebaugh, California · 14155 days ago · 6 km deep · 57 km away
  15. 2.029 km SSW of South Dos Palos, California · 14154 days ago · 0 km deep · 53 km away
  16. 3.828 km SSW of South Dos Palos, California · 14154 days ago · 3 km deep · 53 km away
  17. 2.631 km SSW of South Dos Palos, California · 14154 days ago · 1 km deep · 51 km away
  18. 2.329 km SSW of South Dos Palos, California · 14154 days ago · -1 km deep · 53 km away
  19. 2.032 km SSW of South Dos Palos, California · 14154 days ago · 1 km deep · 50 km away
  20. 2.930 km SSW of South Dos Palos, California · 14154 days ago · 2 km deep · 52 km away
  21. 1.829 km SSW of South Dos Palos, California · 14154 days ago · -1 km deep · 51 km away
  22. 2.0Central California · 14154 days ago · -1 km deep · 50 km away
  23. 1.5Central California · 14154 days ago · -1 km deep · 51 km away
  24. 2.429 km SSW of South Dos Palos, California · 14154 days ago · -1 km deep · 52 km away
  25. 1.8Northern California · 14154 days ago · 7 km deep · 100 km away
  26. 1.625 km ENE of Greenfield, California · 14154 days ago · 6 km deep · 54 km away
  27. 2.229 km SSW of South Dos Palos, California · 14153 days ago · -1 km deep · 53 km away
  28. 1.513 km ENE of East Foothills, California · 14153 days ago · 6 km deep · 73 km away
  29. 1.55 km S of Ridgemark, California · 14152 days ago · 8 km deep · 11 km away
  30. 1.919 km SE of Big Sur, California · 14151 days ago · 14 km deep · 83 km away
  31. 2.120 km SSE of Tres Pinos, California · 14151 days ago · 5 km deep · 26 km away
  32. 1.713 km ESE of East Foothills, California · 14151 days ago · 8 km deep · 62 km away
  33. 2.126 km SW of Firebaugh, California · 14151 days ago · 0 km deep · 57 km away
  34. 1.69 km NE of Morgan Hill, California · 14151 days ago · 5 km deep · 45 km away
  35. 2.029 km SSW of South Dos Palos, California · 14150 days ago · 3 km deep · 53 km away
  36. 2.031 km SSW of South Dos Palos, California · 14150 days ago · 3 km deep · 52 km away
  37. 2.428 km SSW of South Dos Palos, California · 14150 days ago · -1 km deep · 52 km away
  38. 2.829 km SSW of South Dos Palos, California · 14150 days ago · 0 km deep · 53 km away
  39. 1.829 km SSW of South Dos Palos, California · 14150 days ago · 0 km deep · 53 km away
  40. 2.021 km NE of Soledad, California · 14150 days ago · 7 km deep · 36 km away
  41. 2.120 km SSE of Tres Pinos, California · 14150 days ago · 5 km deep · 27 km away
  42. 1.96 km SW of Spreckels, California · 14149 days ago · 11 km deep · 46 km away
  43. 1.917 km SSE of Livermore, California · 14149 days ago · 5 km deep · 84 km away
  44. 1.921 km NNE of Soledad, California · 14149 days ago · 8 km deep · 30 km away
  45. 1.726 km NE of Soledad, California · 14148 days ago · 10 km deep · 36 km away
  46. 1.626 km NE of Soledad, California · 14148 days ago · 10 km deep · 36 km away
  47. 1.626 km NE of Soledad, California · 14148 days ago · 10 km deep · 36 km away
  48. 2.332 km SSW of South Dos Palos, California · 14147 days ago · 1 km deep · 52 km away
  49. 1.713 km SSE of Tres Pinos, California · 14146 days ago · 4 km deep · 20 km away
  50. 2.2Central California · 14145 days ago · -1 km deep · 54 km away
  51. 1.816 km NE of East Foothills, California · 14145 days ago · 2 km deep · 77 km away
  52. 1.99 km S of San Juan Bautista, California · 14145 days ago · 8 km deep · 24 km away
  53. 1.528 km SSW of South Dos Palos, California · 14145 days ago · 0 km deep · 54 km away
  54. 1.514 km SSE of Livermore, California · 14144 days ago · 7 km deep · 86 km away
  55. 3.58 km ENE of San Martin, California · 14144 days ago · 8 km deep · 35 km away
  56. 1.68 km ENE of San Martin, California · 14144 days ago · 7 km deep · 35 km away
  57. 2.921 km NE of Soledad, California · 14144 days ago · 6 km deep · 38 km away
  58. 2.121 km NE of Soledad, California · 14144 days ago · 5 km deep · 37 km away
  59. 1.821 km NE of Soledad, California · 14143 days ago · 5 km deep · 38 km away
  60. 1.86 km SW of Gilroy, California · 14143 days ago · 7 km deep · 31 km away

The first 60 of 168.

Before

  1. 1.812 km N of Morgan Hill, California · 14160 days ago · 6 km deep · 52 km away
  2. 1.940 km ENE of Soledad, California · 14161 days ago · 5 km deep · 47 km away
  3. 1.75 km NNE of Tres Pinos, California · 14162 days ago · 6 km deep · 1 km away
  4. 1.628 km NE of San Ardo, California · 14163 days ago · 0 km deep · 92 km away
  5. 1.718 km SSE of Livermore, California · 14163 days ago · 6 km deep · 82 km away
  6. 1.74 km WSW of Cupertino, California · 14164 days ago · 8 km deep · 85 km away
  7. 1.815 km SSE of Livermore, California · 14164 days ago · 6 km deep · 86 km away
  8. 1.98 km ESE of East Foothills, California · 14164 days ago · 8 km deep · 67 km away
  9. 1.513 km N of Morgan Hill, California · 14164 days ago · 5 km deep · 54 km away
  10. 1.823 km SSW of Los Banos, California · 14166 days ago · 0 km deep · 33 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event nc110045. Read Tue, Sep 22, 2026, 8:44 PM UTC.