Cape Mendocino
Encyclopedia
Cape Mendocino located on the Lost Coast
entirely within Humboldt County, California
, USA, is the westernmost point on the coast of California
. (Mendocino County
lies to the south.) It has been a landmark since the 16th century when the Manila Galleon
s would reach the coast here following the prevailing westerlies
all the way across the Pacific, then make their way down the coast all the way to Acapulco, Mexico. Its first lighthouse was lit December 1, 1868, standing on eight prefabricated panels sent up from San Francisco
.
. Three earthquakes with epicenters nearby at Petrolia
and offshore west of Cape Mendocino, 25–26 April 1992, were outstanding, one reaching 7.2 Mw
; they demonstrated that the Cascadia subduction zone is both capable of producing large earthquakes and generating tsunamis. Many geologists and seismologists believe that the main shock in the 1992 sequence may be a forerunner of a much more powerful earthquake in the Pacific Northwest.
Offshore of Cape Mendocino lies the Mendocino Triple Junction
, a geologic triple junction
where three tectonic plates
come together. The San Andreas Fault
, a transform boundary, runs south from the junction, separating the Pacific Plate
and the North American Plate
. To the north lies the Cascadia subduction zone
, where the Gorda Plate
is being subducted under the margin of the North American plate. Running west from the triple junction is the Mendocino Fracture Zone
, the transform boundary between the Gorda Plate and the Pacific Plate.
Lost Coast
The Lost Coast is a mostly undeveloped section of the California North Coast in Mendocino and Humboldt Counties, which includes the King Range. It was named the "Lost Coast" after the area experienced depopulation in the 1930s...
entirely within Humboldt County, California
Humboldt County, California
Humboldt County is a county in the U.S. state of California, located on the far North Coast 200 miles north of San Francisco. According to 2010 Census Data, the county’s population was 134,623...
, USA, is the westernmost point on the coast of 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...
. (Mendocino County
Mendocino County, California
Mendocino County is a county located on the north coast of the U.S. state of California, north of the greater San Francisco Bay Area and west of the Central Valley. As of the 2010 census, the population was 87,841, up from 86,265 at the 2000 census...
lies to the south.) It has been a landmark since the 16th century when the Manila Galleon
Manila Galleon
The Manila galleons or Manila-Acapulco galleons were Spanish trading ships that sailed once or twice per year across the Pacific Ocean between Manila in the Philippines, and Acapulco, New Spain . The name changed reflecting the city that the ship was sailing from...
s would reach the coast here following the prevailing westerlies
Westerlies
The Westerlies, anti-trades, or Prevailing Westerlies, are the prevailing winds in the middle latitudes between 30 and 60 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical...
all the way across the Pacific, then make their way down the coast all the way to Acapulco, Mexico. Its first lighthouse was lit December 1, 1868, standing on eight prefabricated panels sent up from San Francisco
San Francisco, California
San Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...
.
Geology
The Cape Mendocino region of California's north coast is one of the most seismically active regions in the contiguous United StatesContiguous United States
The contiguous United States are the 48 U.S. states on the continent of North America that are south of Canada and north of Mexico, plus the District of Columbia....
. Three earthquakes with epicenters nearby at Petrolia
Petrolia, California
Petrolia is an unincorporated community in Humboldt County, California. It is located southeast of Cape Mendocino, at an elevation of 121 feet . The ZIP Code is 95558....
and offshore west of Cape Mendocino, 25–26 April 1992, were outstanding, one reaching 7.2 Mw
Moment magnitude scale
The moment magnitude scale is used by seismologists to measure the size of earthquakes in terms of the energy released. The magnitude is based on the seismic moment of the earthquake, which is equal to the rigidity of the Earth multiplied by the average amount of slip on the fault and the size of...
; they demonstrated that the Cascadia subduction zone is both capable of producing large earthquakes and generating tsunamis. Many geologists and seismologists believe that the main shock in the 1992 sequence may be a forerunner of a much more powerful earthquake in the Pacific Northwest.
Offshore of Cape Mendocino lies the Mendocino Triple Junction
Mendocino Triple Junction
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...
, a geologic triple junction
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 three tectonic plates
Tectonic Plates
Tectonic Plates is a 1992 independent Canadian film directed by Peter Mettler. Mettler also wrote the screenplay based on the play by Robert Lepage. The film stars Marie Gignac, Céline Bonnier and Robert Lepage.-Plot summary:...
come together. 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...
, a transform boundary, runs south from the junction, separating 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....
and 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...
. To the north lies 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...
, where 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...
is being subducted under the margin of the North American plate. Running west from the triple junction is the Mendocino Fracture Zone
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...
, the transform boundary between the Gorda Plate and the Pacific Plate.