The Maacama Fault is a right lateral-moving (dextral)

geologic fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

located in the

Coast Ranges The Pacific Coast Ranges (officially gazetted as the Pacific Mountain System in the United States; ; ) are the series of mountain ranges that stretch along the West Coast of North America from Alaska south to Northern and Central Mexico. Althoug ...

of northwestern

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. It is considered to be the northernmost segment of the

Hayward Fault The Hayward Fault Zone is a right-lateral strike-slip geologic fault zone capable of generating destructive earthquakes. The fault was first named in the Lawson Report of the 1906 San Francisco Earthquake in recognition of its involvement in the ...

subsystem of the

San Andreas Fault The San Andreas Fault is a continental Fault (geology)#Strike-slip faults, right-lateral strike-slip transform fault that extends roughly through the U.S. state of California. It forms part of the tectonics, tectonic boundary between the Paci ...

zone. Creep along the Maacama is about 8 mm per year, consistent with the steady movement along the rest of the Hayward Fault system. It is also capable of producing large earthquakes. The Maacama Fault runs just east of Ukiah and just west of Willits.

References

USGS Database: Maacama Faultstorage.water.ca.gov: geo_plate_faulting
Seismic faults of California Geology of Sonoma County, California Geology of Mendocino County, California California Coast Ranges {{MendocinoCountyCA-geo-stub