2024 Cape Mendocino earthquake
 | It has been suggested that this article be merged into List of earthquakes in 2024#December. (Discuss) Proposed since December 2024. |
| UTC time | 2024-12-05 18:44:19 |
|---|---|
| USGS-ANSS | ComCat |
| Local date | December 5, 2024 |
| Local time | 10:44 a.m. PST (UTC−08:00) |
| Magnitude | 7.0 Mw |
| Depth | 10 km (6 mi) |
| Epicenter | 40°22′12″N 125°01′30″W / 40.370°N 125.025°W |
| Fault | Mendocino Fracture Zone |
| Type | Strike-slip |
| Areas affected | North Coast, California, United States |
| Max. intensity | MMI VIII (Severe) |
| Aftershocks | 308+ ≥Mw 2.0 (as of 2024/12/10) Largest: ML 4.7[1] |
On December 5, 2024, a Mw 7.0 earthquake struck off the coast of Humboldt County, California, at 10:44 a.m. PST. It was felt in the state's northern regions and in the Central Valley.[2] The earthquake prompted the National Weather Service to issue a tsunami warning which was canceled soon after.
Tectonic setting
[edit]Near Cape Mendocino, the Mendocino triple junction is an area of active seismicity where three tectonic plates come together. The Mendocino Fracture Zone (also known as the Mendocino Fault east of the Gorda Ridge) is a transform fault that separates the Pacific and Gorda plates. To the south, the relative motion between the Pacific plate and North American plate is accommodated by the San Andreas Fault, and to the north, the Gorda plate is converging with the North American plate at the Cascadia subduction zone. Earthquakes within the Gorda plate are the result of north–south compression at the Mendocino Fault.[3]
Earthquake
[edit]The earthquake's epicenter was located offshore, 63 km (39 mi) west of Petrolia and struck at a focal depth of 10 km (6.2 mi).[4] A similarly-sized earthquake of identical mechanism occurred in the area in 1980.[5] According to Harold Tobin, director of the Pacific Northwest Seismic Network, the earthquake occurred along the Mendocino Fracture Zone at the triple junction of three tectonic plates.[6] The rupture initiated along a steeply dipping fault striking either east-southeast or north-northeast, according to the focal mechanism solution. A rupture on the Mendocino Fracture Zone would correspond with the former fault orientation.[4] It is the largest earthquake to strike the state of California since the 2019 Ridgecrest earthquakes, and the strongest to strike the northwestern coast of the state since 2005.[7] People as far away as Phoenix, Arizona, and Vancouver, Canada, reported shaking.[4] By December 10, 308 aftershocks exceeding Mw 2.0 were recorded, with the strongest measuring ML 4.7.[1]
Damage
[edit]Over 10,000 customers in Humboldt County were left without power following the earthquake.[8] Some homes were shifted from their foundations in the Eel River Valley region.[9] In Ferndale, a volunteer firefighter said damage to homes was limited.[10] In Rio Dell, a road was cracked and a gas leak occurred in a middle school.[11] Minor damage also occurred in Fortuna.[12] Many stores incurred damage from fallen merchandise and goods.[13]
Response
[edit]A tsunami warning was issued by the National Weather Service (NWS) for the northern California and Oregon coast. In San Francisco, Bay Area Rapid Transit ceased all services on the Transbay Tube.[14][15] The San Francisco Zoo was closed, with guests being evacuated and animals secured.[16] An estimated 5.3 million people in California were affected by the tsunami warning.[17] The warning was canceled by the NWS at 11:54 PST.[18] During the tsunami warning period, some people along the beaches of San Francisco and schools in Pacifica and Arcata were evacuated.[13]
California governor Gavin Newsom said the state's emergency offices were "actively responding" to the situation.[19] Mike McGuire, the President pro tempore of the California State Senate, wrote on X (formerly Twitter) that the state was "sending immediate assistance" to Humboldt County and Del Norte County "to assist with emergency operations".[9] A few hours after the earthquake, Newsom declared a state of emergency in Del Norte, Humboldt and Mendocino counties in order to support the emergency response.[20]
See also
[edit]
- List of earthquakes in California
- List of earthquakes in 2024
- 1700 Cascadia earthquake
- 1980 Eureka earthquake
- 1992 Cape Mendocino earthquakes
- 2022 Ferndale earthquake
References
[edit]- ^ a b ANSS (6 December 2024). "Search Results". U.S. Geological Survey.
- ^ Padilla, Cecilio (5 December 2024). "7.0 magnitude earthquake hits off Northern California coast, tsunami warning issued". CBS News. Retrieved 5 December 2024.
- ^ Bakun, W. H. (2000), "Seismicity of California's North Coast", Bulletin of the Seismological Society of America, 90 (4): 797–812, Bibcode:2000BuSSA..90..797B, doi:10.1785/0119990138
- ^ a b c ANSS. "M 7.0 - 2024 Offshore Cape Mendocino, California Earthquake 2024". Comprehensive Catalog. U.S. Geological Survey.
- ^ ANSS. "M 7.2 - The 1980 Eureka, California Earthquake 1980". Comprehensive Catalog. U.S. Geological Survey.
- ^ Bush, Evan (5 December 2024). "Tsunami warnings triggered in California and Oregon after 7.0-magnitude earthquake". Retrieved 5 December 2024.
- ^ ANSS. "Search Results". U.S. Geological Survey. Retrieved 5 December 2024.
- ^ Romine, Taylor (5 December 2024). "Over 10,000 outages in Humboldt County". CNN. Retrieved 5 December 2024.
- ^ a b @ilike_mike (2024-12-05). "The State is sending immediate assistance to Humboldt & Del Norte Counties to assist with emergency operations" (Tweet). Retrieved 2024-12-05 – via Twitter.
- ^ Knoll, Corina (5 December 2024). "Live Updates: 7.0 Earthquake Rattles Northern California and Prompts Brief Tsunami Warning". The New York Times. Retrieved 5 December 2024.
A fire official in Ferndale, the closest town to the quake's epicenter, said it suffered only minor property damage and that no injuries had been reported. The small town relies on an entirely volunteer fire department made up of about 25 people.
- ^ "7.0 magnitude earthquake reported off Northern California coast, tsunami warning canceled". ABC7 News. 5 December 2024. Retrieved 5 December 2024.
Rio Dell Mayor Debra Garnes tells ABC News that there are no injuries reported, but there are cracks in the road and one middle school had a gas leak as a result of the earthquake. The Ferndale city manager reported minor damage related to roofs.
- ^ "7.0 magnitude earthquake strikes Humboldt County, tsunami warning canceled". KTVU. 6 December 2024. Retrieved 6 December 2024.
- ^ a b Baker, Alex (6 December 2024). "Northern California earthquake damage: Photos". KRON-TV. Retrieved 6 December 2024.
- ^ @SFBARTalert (2024-12-05). "BART service has stopped in the Transbay Tube in all directions due to an earthquake detected" (Tweet). Retrieved 2024-12-05 – via Twitter.
- ^ Medina, Madilynne (5 December 2024). "7.0 magnitude earthquake hits Northern California, tsunami warning issued". SFGate. Retrieved 5 December 2024.
- ^ @sfzoo (2024-12-05). "The Zoo has closed due to national weather emergency and tsunami warning" (Tweet). Retrieved 2024-12-05 – via Twitter.
- ^ "Earthquake strikes off coast of Northern California; tsunami warning issued". KETV. Associated Press. 5 December 2024. Retrieved 5 December 2024.
- ^ "Public Tsunami Message Number 3". National Tsunami Warning Center. 5 December 2024. Retrieved 5 December 2024.
- ^ Deliso, Meredith (5 December 2024). "The epicenter is near Petrolia, in Humboldt County, the USGS said". ABC News. Retrieved 5 December 2024.
- ^ "Governor Newsom issues emergency proclamation to support response to Northern California earthquake". Governor of California. 5 December 2024. Retrieved 5 December 2024.