The Mount Diablo Thrust Fault, also known as the Mount Diablo Blind Thrust, is a

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. I ...

in the vicinity of

Mount Diablo Mount Diablo is a mountain of the Diablo Range, in Contra Costa County, California, Contra Costa County of the eastern San Francisco Bay Area in Northern California. It is south of Clayton, California, Clayton and northeast of Danville, Califo ...

Contra Costa County, California Contra Costa County (; ''Contra Costa'', Spanish for 'Opposite Coast') is a county located in the U.S. state of California, in the East Bay of the San Francisco Bay Area. As of the 2020 United States census, the population was 1,165,927. Th ...

. The fault lies between the

Calaveras Fault The Calaveras Fault is a major branch of the San Andreas Fault System that is located in northern California in the San Francisco Bay Area. Activity on the different segments of the fault includes moderate and large earthquakes as well as aseis ...

, the Greenville Fault, and the Concord Fault, all right-lateral

strike-slip 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 ...

s, and appears to transfer movement from the Calaveras and Greenville Faults to the Concord Fault, while continuing to uplift Mount Diablo.

Tectonic forces

The Pacific plate is a major section of the Earth's crust, gradually expanding by the eruption of magma along the

East Pacific Rise The East Pacific Rise (EPR) is a mid-ocean rise (usually termed an oceanic rise and not a mid-ocean ridge due to its higher rate of spreading that results in less elevation increase and more regular terrain), at a divergent tectonic plate bound ...

to the southeast. It is also being subducted far to the northwest into the

Aleutian Trench The Aleutian Trench (or Aleutian Trough) is an oceanic trench along a convergent plate boundary which runs along the southern coastline of Alaska and the Aleutian islands. The trench extends for from a triple junction in the west with the Ula ...

under the North American plate well north of San Francisco. In California, the plate borders the North American plate along a transform boundary, the San Andreas Fault. The westward component of the North American plate's motion and the irregularity of the San Andreas Fault results in some compressive force along the San Andreas and its associated faults, thus helping lift the Coast Ranges. The Mount Diablo Thrust Fault and the Great Valley Blind Thrust faults are consequences of this compression. Movement along the Mount Diablo Thrust Fault includes crustal shortening of about 2.6 mm and uplift of about 1 mm per year.

Seismic parameters

The Mount Diablo Thrust Fault is approximately 25 km long, and dips at an angle of 38 degrees to the northeast. The Mount Diablo Thrust Fault is capable of generating an earthquake of magnitude M_W=6.7. The predicted rupture surface begins 8 km below the surface, and there is thus no surface expression of the fault, and a low likelihood of

surface rupture In seismology, surface rupture (or ground rupture, or ground displacement) is the visible offset of the ground surface when an earthquake rupture along a Fault (geology), fault affects the Earth's surface. Surface rupture is opposed by buried rup ...

in the event of a large earthquake on the fault. No large historic earthquakes are known to have occurred on the Mount Diablo Thrust Fault. The recurrence interval for large earthquakes along the fault is predicted to be about 400 years.

Related faults

Compressive stresses are produced by offset and converging slip-strike motions between the

and the Clayton-Marsh Creek-Greenville Fault which manifest in the Mount Diablo Thrust Fault.

Nearby cities

The Mount Diablo Thrust Fault underlays several cities and unincorporated communities in Contra Costa County:

Alamo The Battle of the Alamo (February 23 – March 6, 1836) was a pivotal event and military engagement in the Texas Revolution. Following a 13-day siege, Mexican troops under President General Antonio López de Santa Anna reclaimed the Alam ...

Antioch Antioch on the Orontes (; , ) "Antioch on Daphne"; or "Antioch the Great"; ; ; ; ; ; ; . was a Hellenistic Greek city founded by Seleucus I Nicator in 300 BC. One of the most important Greek cities of the Hellenistic period, it served as ...

, Blackhawk, Brentwood, Clayton, Concord, Danville, Diablo, San Ramon, and Walnut Creek.

References

{{California Faults Seismic faults of California Geology of Contra Costa County, California Mount Diablo Geography of the San Francisco Bay Area Buried rupture earthquakes