Reviewed by USGS93y ago
M6.8 earthquake off the coast of Northern California
Friday, July 6, 1934, 22:48:57 UTC · 41.147°N, 125.589°W
A magnitude 6.8 earthquake struck off the coast of Northern California on Friday, July 6, 1934, 22:48:57 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.1 on January 22, 1923.
- Magnitude
- 6.8
- Strong · mw
- Depth
- 15 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
208 kilotons of TNT
That is about 14 times the Hiroshima bomb. It released about 437 times the energy of a magnitude 5.0.
Tectonic setting
40 km
from the nearest mapped plate boundary, between the Juan de Fuca and North American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
15 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 100 km
USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 32 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.4123 km W of Big Lagoon, CaliforniaJanuary 31, 1922 · 5 km N of this epicenter
- 7.1The 1923 Humboldt County, California EarthquakeJanuary 22, 1923 · 87 km SE of this epicenter
- 6.552 km WNW of Big Lagoon, CaliforniaJuly 15, 1918 · 75 km E of this epicenter
- 6.5235 km W of Port Orford, OregonAugust 5, 1910 · 233 km NW of this epicenter
- 6.5The 1932 Eureka, California EarthquakeJune 6, 1932 · 119 km SE of this epicenter
- 6.4187 km W of Trinidad, CaliforniaDecember 31, 1915 · 66 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 8 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 1 recorded deaths. The most severe:
- 1932M6.5
Eureka
6 Jun 1932 · 119 km away · intensity VIII
1 deathModerate damage ($1–5M)
- 1865
Fort Humboldt, Eureka
1 Oct 1865 · 93 km away · intensity IX
Moderate damage ($1–5M)
- 1922M7.6
Northern
31 Jan 1922 · 18 km away
Limited damage (under $1M)
- 1923M7.1
Northern
22 Jan 1923 · 87 km away · intensity VIII
Limited damage (under $1M)tsunami
- 1873M6.7
Northern
23 Nov 1873 · 163 km away · intensity VIII
Limited damage (under $1M)tsunami
- 1871M5.9
Humboldt County
2 Mar 1871 · 143 km away · intensity VII
Limited damage (under $1M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.