Reviewed by USGSCalifornia46y ago
M2.8 earthquake 4 km NW of Redway, California
Saturday, April 25, 1981, 21:54:34 UTC · 40.145°N, 123.858°W
A magnitude 2.8 earthquake struck 4 km NW of Redway, California on Saturday, April 25, 1981, 21:54:34 UTC, at a depth of 19.2 km (shallow).
- Magnitude
- 2.8
- Minor · md
- Depth
- 19 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
239 kg of TNT
That is about 1/63,000 of the Hiroshima bomb. A magnitude 5.0 releases about 1,995 times more energy.
Tectonic setting
35 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
19 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 5 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.9 on May 24, 1981. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 2.911 km S of Scotia, California46y ago · 34 km NW of this epicenter
- 2.83 km SSW of Scotia, California46y ago · 41 km NW of this epicenter
- 2.917 km SW of Mad River, California46y ago · 28 km NE of this epicenter
- 2.916 km SW of Mad River, California46y ago · 29 km NE of this epicenter
- 2.56 km NW of Redcrest, California46y ago · 35 km N of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 120 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 · 289 km SE of this epicenter
- 7.4123 km W of Big Lagoon, CaliforniaJanuary 31, 1922 · 188 km NW of this epicenter
- 7.2The 1980 Eureka, California EarthquakeNovember 8, 1980 · 113 km N of this epicenter
- 7.1The 1923 Humboldt County, California EarthquakeJanuary 22, 1923 · 107 km W of this epicenter
- 6.8123 km W of Ferndale, CaliforniaNovember 25, 1954 · 161 km W of this epicenter
- 6.884 km W of Ferndale, CaliforniaFebruary 9, 1941 · 132 km NW of this epicenter
- 6.8off the coast of Northern CaliforniaJuly 6, 1934 · 184 km NW of this epicenter
- 6.552 km WNW of Big Lagoon, CaliforniaJuly 15, 1918 · 150 km NW 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 703 recorded deaths. The most severe:
- 1906M7.9
San Francisco
18 Apr 1906 · 300 km away · intensity XI
700 deaths$400 million damagetsunami
- 1969M4.8
Santa Rosa
2 Oct 1969 · 212 km away · intensity VIII
1 death$8 million damage
- 1954M6.6
Humboldt County
21 Dec 1954 · 78 km away
1 death$2 million damage
- 1932M6.5
Eureka
6 Jun 1932 · 74 km away · intensity VIII
1 deathModerate damage ($1–5M)
- 1980M7.2
North Coast
8 Nov 1980 · 113 km away · intensity VII
$2 million damage
- 1898M6.5
Sonoma County
31 Mar 1898 · 250 km away · intensity VIII
Moderate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.