Preliminary21y ago
M2.5 earthquake near the coast of Northern California
Friday, August 12, 2005, 07:56:13 UTC · 40.190°N, 124.052°W
A magnitude 2.5 earthquake struck near the coast of Northern California on Friday, August 12, 2005, 07:56:13 UTC, at a depth of 6.3 km (shallow).
- Magnitude
- 2.5
- Minor · md
- Depth
- 6 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
85 kg of TNT
That is about 1/177,558 of the Hiroshima bomb. A magnitude 5.0 releases about 5,623 times more energy.
Tectonic setting
22 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
6 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 M4.1 on August 25, 2005. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 2.529 km SSW of Ferndale, California21y ago · 32 km NW of this epicenter
- 2.714 km SW of Ferndale, California21y ago · 43 km NW of this epicenter
- 4.111km SSW of Ferndale, CA21y ago · 39 km NW of this epicenter
- 3.638 km SW of Ferndale, California21y ago · 45 km W of this epicenter
- 3.028 km SSW of Ferndale, California21y ago · 35 km NW of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 176 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 · 172 km NW of this epicenter
- 7.2The 1992 Petrolia, California EarthquakeApril 25, 1992 · 22 km NW of this epicenter
- 7.2The 1980 Eureka, California EarthquakeNovember 8, 1980 · 104 km N of this epicenter
- 7.2153 km W of Big Lagoon, CaliforniaJune 15, 2005 · 202 km NW of this epicenter
- 7.1The 1923 Humboldt County, California EarthquakeJanuary 22, 1923 · 89 km W of this epicenter
- 7.1121 km W of Ferndale, CaliforniaSeptember 1, 1994 · 140 km W of this epicenter
- 7.0136 km WSW of Brookings, OregonAugust 17, 1991 · 224 km NW of this epicenter
- 6.9103 km W of Pistol River, OregonJuly 13, 1991 · 258 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 5 recorded deaths. The most severe:
- 1993M6.0
Klamath Falls
21 Sep 1993 · 291 km away · intensity VII
2 deaths$8 million damage
- 1969M4.8
Santa Rosa
2 Oct 1969 · 224 km away · intensity VIII
1 death$8 million damage
- 1954M6.6
Humboldt County
21 Dec 1954 · 74 km away
1 death$2 million damage
- 1932M6.5
Eureka
6 Jun 1932 · 63 km away · intensity VIII
1 deathModerate damage ($1–5M)
- 1992M7.1
Humboldt County: Ferndale, Petrolia
25 Apr 1992 · 30 km away · intensity VIII
$75 million damagetsunami
- 2000M5.0
Napa
3 Sep 2000 · 246 km away · intensity VII
$50 million damage
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.