West Napa Fault

The West Napa Fault is a 57 km (35 mi) long geologic fault in Napa County, in the North Bay region of the San Francisco Bay Area in northern California. It is believed to be the northern extension of the Calaveras Fault in the East Bay region.

It has been mapped as a Late Pleistocene-Holocene active fault, and is considered to be predominantly a right lateral strike-slip fault.^[1] The fault was discovered in 1976 by Gene Boudreau, a ground water drilling specialist from Sebastopol.^[2] In 2023 there was data showing that the West Napa Fault is actually nine miles longer than previously known.^[3]

Earthquakes

The West Napa Fault is a likely source for the magnitude 6.0 South Napa earthquake that hit Napa County on August 24, 2014.^[4] Seismologists were not able to determine the exact fault on which the quake occurred, because faults are usually identified by their expression on the surface.^[5]

The epicenter for the 2000 Yountville earthquake which occurred on September 3, 2000, is also near the West Napa Fault.^[6]

References

^ Wesling, John R.; Hanson, Kathryn L. (2008). "Mapping of the West Napa Fault zone for input into the Northern California Quaternary Fault Database" (PDF). United States Geological Survey. Retrieved 25 August 2014.
^ Jensen, Peter (August 31, 2014). "A lesser fault line blamed for Sunday's earthquake". Napa Valley Register. Napa, CA: Lee Enterprises, Inc. Retrieved August 31, 2014.
^ Fault line that caused 2014 Napa quake longer, potentially stronger than previously thought: USGS, ABC7 News San Francisco, 26 December 2023
^ Perlman, David (24 August 2014). "Little-known fault suspected in Northern California quake". San Francisco Chronicle. Retrieved 25 August 2014.
^ "Which fault is it?". Seismo Blog. 24 August 2014. Retrieved 27 August 2014.
^ Courtney, Kevin (September 2, 2001). "Shake up call". Napa Valley Register. Napa, CA: Lee Enterprises, Inc.

[1] Wesling, John R.; Hanson, Kathryn L. (2008). "Mapping of the West Napa Fault zone for input into the Northern California Quaternary Fault Database" (PDF). United States Geological Survey. Retrieved 25 August 2014.

[2] Jensen, Peter (August 31, 2014). "A lesser fault line blamed for Sunday's earthquake". Napa Valley Register. Napa, CA: Lee Enterprises, Inc. Retrieved August 31, 2014.

[3] Fault line that caused 2014 Napa quake longer, potentially stronger than previously thought: USGS, ABC7 News San Francisco, 26 December 2023

[4] Perlman, David (24 August 2014). "Little-known fault suspected in Northern California quake". San Francisco Chronicle. Retrieved 25 August 2014.

[5] "Which fault is it?". Seismo Blog. 24 August 2014. Retrieved 27 August 2014.

[6] Courtney, Kevin (September 2, 2001). "Shake up call". Napa Valley Register. Napa, CA: Lee Enterprises, Inc.

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v t e Seismically active fault zones and tectonic blocks of California
Statewide Faults	San Andreas Fault Salinian Block
Southern California	Brawley Seismic Zone Chino Fault Elsinore Fault Zone Elysian Park Fault Garlock Fault Hollywood fault Hosgri Fault Imperial Fault Zone Laguna Salada Fault Newport–Inglewood Fault Northridge Blind Thrust Fault Peninsular Ranges Puente Hills Fault Raymond Fault Rose Canyon Fault Salton Trough San Cayetano Fault San Diego Trough Fault Zone San Felipe Fault Zone San Gabriel Fault San Jacinto Fault Zone Santa Maria River Fault Santa Ynez Fault Shoreline Fault Sierra Madre Fault Zone Ventura Fault White Wolf Fault Whittier Fault Yorba Linda Fault
Northern California	Bartlett Springs Fault Calaveras Fault Clayton-Marsh Creek-Greenville Fault Concord Fault Hayward Fault Zone Healdsburg Fault Maacama Fault Mendocino Fracture Zone Mendocino Triple Junction Mount Diablo Thrust Fault Monta Vista Fault Nacimiento Fault Pleasanton Fault Rinconada Fault San Gregorio Fault San Pablo Fault Seal Cove Fault Serra Fault Silver Creek Fault Tesla Fault West Napa Fault
Sierra Nevada	Death Valley Fault Zone Furnace Creek Fault Zone Honey Lake Fault Zone Kern Canyon Fault Maria fold and thrust belt Owens Valley Fault Rescue Lineament-Bear Mountains fault zone Sierra Nevada Batholith Sierra Nevada Fault Sierra Nevada–Great Valley Block Smartville Block Walker Lane
Category California Geological Survey Seismic Hazards Mapping Act Mexico (list)

Earthquakes

See also

References