Reviewed by USGSCalifornia35y ago
M3.1 earthquake 7 km NE of Phillipsville, California
Wednesday, November 6, 1991, 02:04:22 UTC · 40.252°N, 123.720°W
A magnitude 3.1 earthquake struck 7 km NE of Phillipsville, California on Wednesday, November 6, 1991, 02:04:22 UTC, at a depth of 27.6 km (shallow).
- Magnitude
- 3.1
- Minor · ml
- Depth
- 28 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 earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
674 kg of TNT
That is about 1/22,353 of the Hiroshima bomb. A magnitude 5.0 releases about 708 times more energy.
Tectonic setting
50 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
28 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 50 km
USGS lists 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.8 on November 17, 1991. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 134 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.9The 1906 San Francisco, California EarthquakeApril 18, 1906 · 296 km S of this epicenter
- 7.4123 km W of Big Lagoon, CaliforniaJanuary 31, 1922 · 190 km NW of this epicenter
- 7.2The 1980 Eureka, California EarthquakeNovember 8, 1980 · 106 km NW of this epicenter
- 7.1The 1923 Humboldt County, California EarthquakeJanuary 22, 1923 · 114 km W of this epicenter
- 7.0136 km WSW of Brookings, OregonAugust 17, 1991 · 239 km NW of this epicenter
- 6.9103 km W of Pistol River, OregonJuly 13, 1991 · 268 km NW of this epicenter
- 6.8123 km W of Ferndale, CaliforniaNovember 25, 1954 · 170 km W of this epicenter
- 6.884 km W of Ferndale, CaliforniaFebruary 9, 1941 · 138 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 25 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 3 recorded deaths. The most severe:
- 1969M4.8
Santa Rosa
2 Oct 1969 · 217 km away · intensity VIII
1 death$8 million damage
- 1954M6.6
Humboldt County
21 Dec 1954 · 68 km away
1 death$2 million damage
- 1932M6.5
Eureka
6 Jun 1932 · 71 km away · intensity VIII
1 deathModerate damage ($1–5M)
- 1980M7.2
North Coast
8 Nov 1980 · 106 km away · intensity VII
$2 million damage
- 1898M6.5
Sonoma County
31 Mar 1898 · 255 km away · intensity VIII
Moderate damage ($1–5M)tsunami
- 1892M6.2
Winters
21 Apr 1892 · 250 km away · intensity IX
Moderate damage ($1–5M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.