United States – Contra Costa County

This page summarizes earthquakes in Contra Costa County (United States). The most recently recorded event was a magnitude M2.2 earthquake near San Ramon on 2026-06-18 22:54:36 UTC. All event lists and map markers are limited to the last 30 days.

About Contra Costa County

Contra Costa County is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. As of the 2020 United States census, the population was 1,165,927. The county seat is Martinez.

Earthquakes (last 30 days)
22
Max magnitude (last 30 days)
M2.2
Avg magnitude (last 30 days)
M1.52
Avg depth (last 30 days)
10 km
Seismic activity in 2026

In 2026, Contra Costa County recorded 157 earthquakes within United States. The average magnitude was M1.86. The strongest event reached M4.2.

By event count in 2026, this region ranks #26 within United States.

Located on the North America Plate.

Map (last 30 days)
< 2 2–4 4–5 ≥ 5
Earthquakes in Contra Costa County (last 30 days)
M2.2
San Ramon
2026-06-18 · 22:54 UTC · 8 km
›
M1.3
Walnut Creek
2026-06-18 · 21:59 UTC · 8 km
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M1.6
Hercules
2026-06-18 · 19:59 UTC · 8 km
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M1.3
Walnut Creek
2026-06-15 · 13:35 UTC · 12 km
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M1.7
North Gate
2026-06-15 · 09:17 UTC · 9 km
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M0.9
Walnut Creek
2026-06-15 · 07:46 UTC · 13 km
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M1.0
Walnut Creek
2026-06-14 · 11:24 UTC · 11 km
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M1.3
Danville
2026-06-14 · 03:03 UTC · 6 km
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M1.0
Camino Tassajara
2026-06-14 · 03:02 UTC · 15 km
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M1.7
Walnut Creek
2026-06-13 · 15:34 UTC · 8 km
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M1.4
San Ramon
2026-06-12 · 03:26 UTC · 5 km
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M1.1
Walnut Creek
2026-06-11 · 13:19 UTC · 12 km
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M1.7
Walnut Creek
2026-06-07 · 11:19 UTC · 12 km
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M1.5
San Ramon
2026-06-05 · 04:20 UTC · 8 km
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M1.1
Hercules
2026-05-30 · 17:32 UTC · 8 km
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M1.5
North Gate
2026-05-30 · 10:08 UTC · 11 km
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M2.2
Walnut Creek
2026-05-27 · 08:23 UTC · 12 km
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M1.8
Walnut Creek
2026-05-27 · 04:51 UTC · 12 km
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M1.5
Walnut Creek
2026-05-27 · 04:27 UTC · 12 km
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M2.1
Walnut Creek
2026-05-27 · 04:24 UTC · 12 km
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M2.0
Walnut Creek
2026-05-27 · 04:11 UTC · 12 km
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M1.0
Glen Frazer
2026-05-26 · 15:20 UTC · 7 km
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