Mendocino Triple Junction
Encyclopedia
The Mendocino Triple Junction is a geologic triple junction
where the San Andreas Fault
meets the Mendocino Fault
and the Cascadia subduction zone
, separating three tectonic plates: the Pacific Plate
, the North American Plate
and the Gorda Plate
. It is located just offshore of Cape Mendocino
in northern California
.
It is one of the most seismically active regions of the San Andreas transform system
. Since 1983 the region has generated about 80 greater than or equal to M3.0 quakes each year, and historically the region has experienced major quakes. This activity is generated in response to ongoing plate motions between the Gorda, North America, and Pacific plates.
Triple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction a boundary will be one of 3 types - a ridge, trench or transform fault - and triple junctions can be described according to the types of plate margin that meet at them...
where the San Andreas Fault
San Andreas Fault
The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
meets the Mendocino Fault
Mendocino Fracture Zone
The Mendocino Fracture Zone is a fracture zone and transform boundary off the coast of Cape Mendocino in far northern California. It runs westward from a triple junction with the San Andreas Fault and the Cascadia subduction zone to the southern end of the Gorda Ridge...
and the Cascadia subduction zone
Cascadia subduction zone
The Cascadia subduction zone is a subduction zone, a type of convergent plate boundary that stretches from northern Vancouver Island to northern California. It is a very long sloping fault that separates the Juan de Fuca and North America plates.New ocean floor is being created offshore of...
, separating three tectonic plates: the Pacific Plate
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....
, the North American Plate
North American Plate
The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, Bahamas, and parts of Siberia, Japan and Iceland. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust...
and the Gorda Plate
Gorda Plate
The Gorda Plate, located beneath the Pacific Ocean off the coast of northern California, is one of the northern remnants of the Farallon Plate. It is sometimes referred to as simply the southernmost portion of the neighboring Juan de Fuca Plate, another Farallon remnant.Unlike most tectonic...
. It is located just offshore of Cape Mendocino
Cape Mendocino
Cape Mendocino located on the Lost Coast entirely within Humboldt County, California, USA, is the westernmost point on the coast of California. It has been a landmark since the 16th century when the Manila Galleons would reach the coast here following the prevailing westerlies all the way across...
in northern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
.
It is one of the most seismically active regions of the San Andreas transform system
San Andreas Fault
The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
. Since 1983 the region has generated about 80 greater than or equal to M3.0 quakes each year, and historically the region has experienced major quakes. This activity is generated in response to ongoing plate motions between the Gorda, North America, and Pacific plates.