2022 Ferndale earthquake

{{Infobox earthquake

| name = 2022 Ferndale earthquake

| timestamp = 2022-12-20 10:34:25

| anss-url = nc73821036

| isc-event = 625455849

| image =

| alt =

| caption =

| map = {{OSM Location map

| coord = {{coord|40.525|-124.423}}

| zoom = 7

| width = 260

| height = 150

| label =

| float = center

| label-pos =

| mark = Bullseye1.svg

| mark-size = 70

| mark-coord = {{coord|40.525|-124.423}}

| mark-description =M6.4

}}

| map_alt =

| map_caption =

| map2 =

| local-date = {{Start date|2022|12|20}}

| local-time = 02:34 PST (UTC−08:00)

| duration =

| magnitude = 6.4 {{M|w|link=y}}

| depth = {{cvt|17.9|km|abbr=on|0}}

| location = {{coord|40.525|N|124.423|W|region:US_type:event|display=inline,title}}

| type =

| affected = North Coast, California, United States

| fault =

| damages =

| landslide =

| intensity = {{MMI|8}}{{cite web |title=M 6.4 – 15 km WSW of Ferndale, CA |url=https://earthquake.usgs.gov/earthquakes/eventpage/nc73821036/impact |department=Earthquake Hazards Program |publisher=United States Geological Survey}}

| pga = 1.46 g{{Cite web |title=Ferndale Earthquake of 20 Dec 2022 |url=https://www.strongmotioncenter.org/cgi-bin/CESMD/iqr_dist_DM2_sr.pl?IQRID=nc73821036&SFlag=0&Flag=2 |publisher=Center for Engineering Strong Motion Data}}

| tsunami =

| foreshocks =

| aftershocks = 271 above {{M|w}}1.0. Largest is {{M|w}}5.4.

| casualties = 2 dead {{Small|(indirect)}}, 17 injured

| engvar = en-us

}}

On December 20, 2022, a magnitude 6.4 earthquake struck Ferndale, California in Humboldt County, United States at 10:34:25 UTC, or 2:34 a.m. PST.{{cite web |title=M 6.4 – 15 km WSW of Ferndale, California |url=https://earthquake.usgs.gov/earthquakes/eventpage/nc73821036/executive |department=Earthquake Hazards Program |publisher=United States Geological Survey}} {{PD-notice}}

Tectonic setting

Much of Northern California lies close to the boundaries between three tectonic plates, the Pacific plate, the Gorda plate and the North American plate, which meet at the Mendocino triple junction. The Mendocino fracture zone marks the transform boundary between the Gorda and Pacific plates.{{Cite journal |last1=Gulick |first1=Sean P. S. |last2=Meltzer |first2=Anne S. |last3=Henstock |first3=Timothy J. |last4=Levander |first4=Alan |date=2001-08-01 |title=Internal deformation of the southern Gorda plate: Fragmentation of a weak plate near the Mendocino triple junction |url=https://ui.adsabs.harvard.edu/abs/2001Geo....29..691G |journal=Geology |volume=29 |issue=8 |pages=691 |doi=10.1130/0091-7613(2001)029<0691:IDOTSG>2.0.CO;2|bibcode=2001Geo....29..691G }} This tectonic boundary has been the cause of many earthquakes in the region, including the megathrust 1700 Cascadia earthquake, and the 1992 Cape Mendocino earthquakes, the latter of which measured 7.2.{{Cite journal |last1=Toppozada |first1=T. |last2=Branum |first2=D. |date=2004-12-25 |title=California earthquake history |url=https://pubs.er.usgs.gov/publication/70026823 |journal=Annals of Geophysics|volume=47 |issue=2–3 |doi=10.4401/ag-3317 |issn=2037-416X |id=ResearchGate id:[https://www.researchgate.net/publication/50301779 50301779] |hdl=2122/776 |s2cid=129861897|doi-access=free }}

Earthquake

File:Offshore northern California magnitude 6.4 earthquake (2-34 AM, 20 December 2022).png

The earthquake measured 6.4 on the moment magnitude scale, and had a maximum Mercalli intensity of VIII (Severe). It came exactly a year after a 6.2 magnitude earthquake struck onshore in the Cape Mendocino area on December 20, 2021,{{Cite web |title=M 6.2 – 7 km N of Petrolia, California |url=https://earthquake.usgs.gov/earthquakes/eventpage/nc73666231/executive |department=Earthquake Hazards Program |publisher=United States Geological Survey}} causing only minor damage.{{Cite news |last=Guilfoil |first=Jackson |date=December 21, 2021 |title=Earthquake causes minor property, road damage |url=https://www.times-standard.com/2021/12/21/earthquake-causes-minor-property-road-damage/ |website=Times-Standard}} It was the result of strike-slip faulting along either a southeast or southwest striking plane. The United States Geological Survey said the earthquake's depth, focal mechanism, and location suggest a likely source within the subducting Gorda plate. Despite being centered offshore, the fault that triggered the quake travelled onshore and ruptured northeasternwards.{{Cite news |last1=Petri |first1=Alexandra E. |last2=Lin |first2=Summer |date=December 21, 2022 |title=Northern California towns tally earthquake damage as power is restored to tens of thousands |url=https://www.latimes.com/california/story/2022-12-21/california-earthquake-aftermath-damage |work=Los Angeles Times}}

=Aftershocks=

Following the mainshock, over 250 aftershocks above magnitude 1.0 occurred, distributed along a distance of {{cvt|26|km}}.{{Cite web |title=Latest Earthquakes |url=https://earthquake.usgs.gov/earthquakes/map/?extent=39.2918,-125.37598&extent=41.87774,-123.31604&range=search&baseLayer=terrain&timeZone=utc&map=false&search=%7B%22name%22:%22Search%20Results%22,%22params%22:%7B%22endtime%22:%222030-01-10T10:34:24.770Z%22,%22latitude%22:40.525,%22longitude%22:-124.423,%22maxradiuskm%22:100,%22minmagnitude%22:1,%22starttime%22:%222022-12-20T10:35:00.770Z%22%7D%7D |publisher=United States Geological Survey}} The largest aftershock of the year measured 4.9 magnitude with a maximum intensity of V (Moderate).{{Cite web |title=M 4.9 – 7 km WNW of Rio Dell, California |url=https://earthquake.usgs.gov/earthquakes/eventpage/nc73821046/ |department=Earthquake Hazards Program |publisher=United States Geological Survey}} On January 1, 2023, a magnitude 5.4 aftershock struck, with a maximum intensity of VII.{{Cite web |title=M 5.4 – 15 km SE of Rio Dell, California |url=https://earthquake.usgs.gov/earthquakes/eventpage/nc73827571/executive |department=Earthquake Hazards Program |publisher=United States Geological Survey}} Broken windows, large cracks in buildings and power outages were reported in Humboldt County due to this aftershock, and some houses were badly damaged after being shaken from their foundations.{{Cite news |last=Nelson |first=Laura J. |date=January 1, 2023 |title=Earthquake: Magnitude 5.4 quake hits Northern California days after deadly temblor |url=https://www.latimes.com/california/story/2023-01-01/earthquake-5-4-quake-registered-near-fortuna-calif |website=Los Angeles Times}} A magnitude 4.5 earthquake struck six miles west-southwest of Ferndale on March 21 and was attributed as an aftershock by the USGS.{{Cite news |last=Wear |first=Kimberly |date=March 23, 2023 |title=Another Aftershock|pages=7 |work=The Ferndale Enterprise |publisher=North Coast Journal |publication-place=Eureka, California |editor-last=Greenson |editor-first=Thadeus}}

Impact

=Casualties=

Two people died due to "medical emergencies" involved with the earthquake, and seventeen others were injured.{{Cite news |last1=Boyette |first1=Chris |last2=Romine |first2=Taylor |date=December 21, 2022 |title=17 people were injured in the California earthquake that also left 2 dead |url=https://edition.cnn.com/2022/12/21/us/humboldt-county-california-earthquake-wednesday/index.html |quote=California earthquake: 17 people injured, thousands without power |publisher=CNN}} In both fatalities, ages 72 and 83, emergency workers were unable to attend to them because ambulances were responding to other areas. One of the deaths was related to a cardiac arrest.{{cite news |last1=Johnson |first1=Julie |last2=Flores |first2=Jessica |last3=Morris |first3=J. D. |last4=Tucker |first4=Jill |date=December 20, 2022 |title=Two dead in 6.4 magnitude California earthquake that causes widespread damage |work=San Francisco Chronicle |url=https://www.sfchronicle.com/california/article/6-4-magnitude-earthquake-strikes-Northern-17666216.php |access-date=December 20, 2022}}{{Cite news |last1=Da Silva |first1=Chantal |author-link=Chantal Da Silva |last2=Li |first2=David K. |last3=Stelloh |first3=Tim |date=December 20, 2022 |title=At least 2 dead as 6.4-magnitude earthquake rocks Northern California |publisher=NBC News |url=https://www.nbcnews.com/news/rcna62522}}

=Damage=

File:2022-1220 Ferndale Earthquake Fernbridge Damage5.png.]]

Initial reports (via radio scanner traffic) indicated several houses were damaged, numerous gas leaks, and power outages in Rio Dell.{{Cite news |author=Dooley |first=Matthew |date=December 20, 2022 |title=California rocked by 6.4 magnitude earthquake sparking 'structural collapse' and gas leaks |work=Daily Express |url=https://www.express.co.uk/news/us/1711720/california-earthquake-magnitude-eureka-ferndale-tsunami-warning-dxus}} Fifteen buildings collapsed or were severely damaged, including one in a fire caused by the tremors.{{Cite news |date=December 20, 2022 |title=Tens of thousands without power after California earthquake |publisher=NBC News |agency=Associated Press |location=Rio Dell |url=https://www.nbc15.com/2022/12/20/64-magnitude-earthquake-detected-northern-california/}}{{Cite news |date=December 21, 2022 |title=Deadly California earthquake leaves thousands without power |publisher=BBC News |url=https://www.bbc.co.uk/news/world-us-canada-64046462}} About 100 people were displaced due to damaged homes. Glass windows in stores were shattered and homes knocked off their foundations. At Loleta, bricks toppled from the former Humboldt Creamery building. Some businesses in Fortuna and Ferndale sustained damage at storefronts and products fell.{{cite news |last1=Graff |first1=Amy |last2=Dowd |first2=Katie |last3=Bindman |first3=Ariana |date=December 20, 2022 |title=Live updates: No water in badly damaged town after 6.4 magnitude California earthquake |work=San Francisco Chronicle |url=https://www.sfgate.com/bayarea/article/california-earthquake-live-updates-17666750.php}} A total of up to 150 homes were damaged or destroyed due to the quake, most of them in Rio Dell.

Pacific Gas and Electric (PG&E) at first estimated that 50,000 people were without power in Humboldt County, a number later revised to 60,000.{{Cite news |last=Dreier |first=Natalie |date=December 20, 2022 |title=6.4-magnitude earthquake rocks Northern California |work=FOX23 News |url=https://www.fox23.com/news/trending/64-magnitude-earthquake-rocks-northern-california/XHWAV47VX5AE3MJQOJEC3TP4O4/}} The California Independent System Operator (CAISO) declared a transmission emergency.{{Cite news |date=December 23, 2022 |title=Quick Bites: Energy News Roundup |url=https://www.newsdata.com/california_energy_markets/news_in_brief/quick-bites-energy-news-roundup/article_f488df46-830d-11ed-8863-4ff0b9d85501.html |website=California Energy Markets |publisher=NewsData}} Phones were alerted of the coming earthquake as far south as the San Francisco Bay Area.{{Cite news |last=Brinkley |first=Leslie |date=December 20, 2022 |title=MyShake app successfully warned Bay Area residents of NorCal earthquake |url=https://abc7news.com/earthquake-california-myshake-app-ca-warning-alert-bay-area/12594884/ |publisher=ABC7 San Francisco }} As of 4:25 am. PST, PG&E revised the total of customers without power to 71,170.{{Cite web |title=PGE Emergency Site – Outage Center |url=https://pgealerts.alerts.pge.com/outagecenter/ |publisher=Pacific Gas and Electric (PG&E)}} Caltrans District 1 closed the Fernbridge over the Eel River on California State Route 211 due to four cracks which could cause the road itself to slide off.{{Cite news |last1=Sangal |first1=Aditi |last2=Vales |first2=Leinz |last3=Macaya |first3=Melissa |date=December 20, 2022 |title=Live updates: A 6.4-magnitude earthquake strikes Northern California |publisher=CNN|url=https://www.cnn.com/us/live-news/northern-california-earthquake-humboldt-county/index.html}} The California Office of Emergency Services (Cal OES) coordinated the responses of local governments (including tribal authorities), Cal Fire, Caltrans, the California Geological Survey, and the California Highway Patrol. Cal Poly Humboldt University was closed to all except essential personnel as of 7:16 am.{{Cite web |title=Cal Poly Humboldt: Emergency Conditions |url=https://www.humboldt.edu/emergency |publisher=Cal Poly Humboldt}}

Response

The earthquake activated ShakeAlert, USGS's earthquake early warning system for the West Coast. Three million people in northern California and southern Oregon received warnings on their smartphones. Sensors at Fortuna detected the earthquake at 02:34 and issued warnings as far as the California–Oregon border, south of San Jose, past Shasta County and to Medford, Oregon. The warning issued was the most widespread since the system went public in 2019.{{cite news |last1=Skropanic |first1=Jessica |date=December 20, 2022 |title=Humboldt earthquake alert warned 3M people in California, Oregon |work=Record Searchlight |url=https://www.redding.com/story/news/2022/12/20/humboldt-earthquake-alert-warned-3-million-people-in-california-oregon/69744720007/}} The National Oceanic and Atmospheric Administration (NOAA) did not issue a tsunami alert and no tsunami occurred.{{Cite web |title=U.S. Tsunami Warning Centers |url=https://www.tsunami.gov/?p=PAAQ/2022/12/20/rn6qpb/1/WEAK53 |publisher=National Oceanic and Atmospheric Administration}}

Many local NGOs and government entities responded, including Humboldt County Office of Emergency Services, Humboldt County Department of Health and Human Services, Pay It Forward Humboldt, and World Central Kitchen.