Reviewed by USGSCalifornia35y ago
M4.3 earthquake 38 km W of Crescent City, California
Monday, July 29, 1991, 04:07:10 UTC · 41.779°N, 124.661°W
A magnitude 4.3 earthquake struck 38 km W of Crescent City, California on Monday, July 29, 1991, 04:07:10 UTC, at a depth of 28.0 km (shallow).
- Magnitude
- 4.3
- Light · 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
43 tons of TNT
That is about 1/354 of the Hiroshima bomb. A magnitude 5.0 releases about 11 times more energy.
Tectonic setting
52 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
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 7 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.1 on August 17, 1991. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 2.569 km W of Crescent City, California35y ago · 33 km W of this epicenter
- 3.080 km WSW of Brookings, Oregon35y ago · 43 km W of this epicenter
- 2.871 km WSW of Brookings, Oregon35y ago · 39 km W of this epicenter
- 2.868 km WSW of Brookings, Oregon35y ago · 31 km W of this epicenter
- 2.576 km W of Crescent City, California35y ago · 39 km W of this epicenter
- 3.139 km WSW of Crescent City, California35y ago · 16 km S of this epicenter
- 2.673 km WSW of Crescent City, California35y ago · 41 km SW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 181 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 · 103 km SW of this epicenter
- 7.2The 1980 Eureka, California EarthquakeNovember 8, 1980 · 81 km SE of this epicenter
- 7.1The 1923 Humboldt County, California EarthquakeJanuary 22, 1923 · 148 km S of this epicenter
- 6.9103 km W of Pistol River, OregonJuly 13, 1991 · 93 km NW of this epicenter
- 6.8123 km W of Ferndale, CaliforniaNovember 25, 1954 · 172 km SW of this epicenter
- 6.884 km W of Ferndale, CaliforniaFebruary 9, 1941 · 135 km S of this epicenter
- 6.8off the coast of Northern CaliforniaJuly 6, 1934 · 105 km SW of this epicenter
- 6.7217 km W of Ferndale, CaliforniaSeptember 10, 1984 · 231 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:
- 1954M6.6
Humboldt County
21 Dec 1954 · 122 km away
1 death$2 million damage
- 1932M6.5
Eureka
6 Jun 1932 · 121 km away · intensity VIII
1 deathModerate damage ($1–5M)
- 1980M7.2
North Coast
8 Nov 1980 · 81 km away · intensity VII
$2 million damage
- 1991M6.2
Honeydew, Whitethorn, Petrolia
17 Aug 1991 · 174 km away · intensity VII
Moderate damage ($1–5M)
- 1865
Fort Humboldt, Eureka
1 Oct 1865 · 88 km away · intensity IX
Moderate damage ($1–5M)
- 1922M7.6
Northern
31 Jan 1922 · 111 km away
Limited damage (under $1M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.