Cape Mendocino

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The Cape Mendocino Coast. Cape Mendocino Coast.jpg
The Cape Mendocino Coast.

Cape Mendocino, approximately 200 miles north of San Francisco, is located on the Lost Coast entirely within Humboldt County, California, USA. At 124° 24' 34" W longitude it is the westernmost point on the coast of California. [1] The South Cape Mendocino State Marine Reserve and Sugarloaf Island are immediately offshore, although closed to public access due to their protected status. [2] [3] Sugarloaf Island is cited as California's westernmost island. [4]

Lost Coast Region of California in the United States

The Lost Coast is a mostly natural and undeveloped area of the California North Coast in Humboldt and Mendocino Counties, which includes the King Range. It was named the "Lost Coast" after the area experienced depopulation in the 1930s. In addition, the steepness and related geotechnical challenges of the coastal mountains made this stretch of coastline too costly for state highway or county road builders to establish routes through the area, leaving it the most undeveloped and remote portion of the California coast. Without any major highways, communities in the Lost Coast region such as Petrolia, Shelter Cove, and Whitethorn are isolated from the rest of California.

Humboldt County, California County in California, United States

Humboldt County is a county in the U.S. state of California. As of the 2010 census, the population was 132,646. The county seat is Eureka.

California State of the United States of America

California is a state in the Pacific Region of the United States. With 39.6 million residents, California is the most populous U.S. state and the third-largest by area. The state capital is Sacramento. The Greater Los Angeles Area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions, with 18.7 million and 9.7 million residents respectively. Los Angeles is California's most populous city, and the country's second most populous, after New York City. California also has the nation's most populous county, Los Angeles County, and its largest county by area, San Bernardino County. The City and County of San Francisco is both the country's second-most densely populated major city after New York City and the fifth-most densely populated county, behind only four of the five New York City boroughs.

Contents

History

Named by Spanish explorer Andrés de Urdaneta in 1565 in honor of Antonio de Mendoza, Viceroy of New Spain, Cape Mendocino has been a landmark since the 16th century, when Manila Galleons followed the prevailing westerlies across the Pacific to the Cape, then followed the coast south to Acapulco, Mexico. The Cape Mendocino Light was lit December 1, 1868, standing on eight prefabricated panels sent up from San Francisco; an automated light stood near the original location but was removed in 2013. [5]

Andrés de Urdaneta Spanish explorer

Friar Andrés de Urdaneta, OSA, was a Spanish Basque circumnavigator, explorer and Augustinian friar. As a navigator he achieved in 1536 the "second" world circumnavigation. Urdaneta discovered and plotted a path across the Pacific from the Philippines to Acapulco in the Viceroyalty of New Spain used by the Manila galleons, which came to be known as "Urdaneta's route". He was considered as "protector of the Indians" for his treatment of the Filipino natives; also Cebu and the Philippines' first prelate.

Antonio de Mendoza Spanish colonial administrator

Antonio de Mendoza y Pacheco was the first Viceroy of New Spain, serving from November 14, 1535 to November 25, 1550, and the third Viceroy of Peru, from September 23, 1551, until his death on July 21, 1552.

New Spain viceroyalty of the Spanish Empire (1535-1821)

The Viceroyalty of New Spain was an integral territorial entity of the Spanish Empire, established by Habsburg Spain during the Spanish colonization of the Americas. It covered a huge area that included territories in North America, South America, Asia and Oceania. It originated in 1521 after the fall of Mexico-Tenochtitlan, the main event of the Spanish conquest, which did not properly end until much later, as its territory continued to grow to the north. It was officially created on 8 March 1535 as a viceroyalty, the first of four viceroyalties Spain created in the Americas. Its first viceroy was Antonio de Mendoza y Pacheco, and the capital of the viceroyalty was Mexico City, established on the ancient Mexico-Tenochtitlan.

Geology

Regional Seismicity 1985-2003 Ferndale Eureka RegionHistoricSeismicity.jpg
Regional Seismicity 1985–2003

The Cape Mendocino region of California's north coast is one of the most seismically active regions in the contiguous United States. Three earthquakes with epicenters nearby at Petrolia and offshore west of Cape Mendocino, 25–26 April 1992, were outstanding, one reaching 7.2 Mw; [6] 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. [7]

Contiguous United States 48 states of the United States apart from Alaska and Hawaii

The contiguous United States or officially the conterminous United States consists of the 48 adjoining U.S. states on the continent of North America. The terms exclude the non-contiguous states of Alaska and Hawaii, and all other off-shore insular areas. These differ from the related term continental United States which includes Alaska but excludes Hawaii and insular territories.

Petrolia, California Unincorporated community in California, United States

Petrolia is an unincorporated community in Humboldt County, California, 10 miles (16 km) southeast of Cape Mendocino, at an elevation of 121 feet (37 m) above sea level, within ZIP Code 95558, and area code 707. Petrolia was the site of the first oil well drilled in California.

1992 Cape Mendocino earthquakes

The 1992 Cape Mendocino earthquakes occurred along the Lost Coast of Northern California on April 25 and 26. The three largest events were the M7.2 thrust mainshock that struck near the unincorporated community of Petrolia midday on April 25 and two primary strike-slip aftershocks measuring 6.5 and 6.6 that followed early the next morning. The sequence encompassed both interplate and intraplate activity that was associated with the Mendocino Triple Junction, a complex system of three major faults that converge near Cape Mendocino. The total number of aftershocks that followed the events exceeded 2,000.

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 Fault, the transform boundary between the Gorda Plate and the Pacific Plate.

Mendocino Triple Junction The point where the Gorda plate, the North American plate, and the Pacific plate meet

The Mendocino Triple Junction (MTJ) is the point where the Gorda plate, the North American plate, and the Pacific plate meet, in the Pacific Ocean near Cape Mendocino in northern California. This triple junction is the location of a change in the broad plate motions which dominate the west coast of North America, linking convergence of the northern Cascadia subduction zone and translation of the southern San Andreas Fault system. The Gorda plate is subducting, towards N50ºE, under the North American plate at 2.5 – 3 cm/yr, and is simultaneously converging obliquely against the Pacific plate at a rate of 5 cm/yr in the direction N115ºE. The accommodation of this plate configuration results in a transform boundary along the Mendocino Fracture Zone, and a divergent boundary at the Gorda Ridge.

Triple junction The point where the boundaries of three tectonic plates meet

A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction each of the three boundaries will be one of 3 types - a ridge (R), trench (T) or transform fault (F) - and triple junctions can be described according to the types of plate margin that meet at them. Of the many possible types of triple junction only a few are stable through time. The meeting of 4 or more plates is also theoretically possible but junctions will only exist instantaneously.

San Andreas Fault A continental transform fault through California between the Pacific Plate and the North American Plate

The San Andreas Fault is a continental transform fault that extends roughly 1,200 kilometers (750 mi) through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate, and its motion is right-lateral strike-slip (horizontal). The fault divides into three segments, each with different characteristics and a different degree of earthquake risk. The slip rate along the fault ranges from 20 to 35 mm /yr.

Coordinates: 40°26′24″N124°24′34″W / 40.4401°N 124.4095°W / 40.4401; -124.4095

Geographic coordinate system Coordinate system

A geographic coordinate system is a coordinate system that enables every location on Earth to be specified by a set of numbers, letters or symbols. The coordinates are often chosen such that one of the numbers represents a vertical position and two or three of the numbers represent a horizontal position; alternatively, a geographic position may be expressed in a combined three-dimensional Cartesian vector. A common choice of coordinates is latitude, longitude and elevation. To specify a location on a plane requires a map projection.

See also

Related Research Articles

Transform fault A plate boundary where the motion is predominantly horizontal

A transform fault or transform boundary is a plate boundary where the motion is predominantly horizontal. It ends abruptly and is connected to another transform, a spreading ridge, or a subduction zone.

North American Plate Large tectonic plate including most of North America, Greenland and a bit of Siberia

The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. 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. The interior of the main continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of crustal material called terranes, accreted to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the Rocky Mountains is composed of such terranes.

Juan de Fuca Plate A small tectonic plate in the western North Pacific

The Juan de Fuca Plate is a tectonic plate generated from the Juan de Fuca Ridge and is subducting under the northerly portion of the western side of the North American Plate at the Cascadia subduction zone. It is named after the explorer of the same name. One of the smallest of Earth's tectonic plates, the Juan de Fuca Plate is a remnant part of the once-vast Farallon Plate, which is now largely subducted underneath the North American Plate.

Gorda Plate One of the northern remnants of the Farallon 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.

Explorer Plate An oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada

The Explorer Plate is an oceanic tectonic plate beneath the Pacific Ocean off the west coast of Vancouver Island, Canada and is partially subducted under the North American Plate. Along with the Juan De Fuca Plate and Gorda Plate, the Explorer Plate is a remnant of the ancient Farallon Plate which has been subducted under the North American Plate. The Explorer Plate separated from the Juan De Fuca Plate roughly 4 million years ago. In its smoother, southern half, the average depth of the Explorer plate is roughly 2,400 metres (7,900 ft) and rises up in its northern half to a highly variable basin between 1,400 metres (4,600 ft) and 2,200 metres (7,200 ft) in depth.

Cascadia subduction zone Convergent plate boundary that stretches from northern Vancouver Island to Northern California

The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, and Gorda plates move to the east and slide below the much larger mostly continental North American Plate. The zone varies in width and lies offshore beginning near Cape Mendocino Northern California, passing through Oregon and Washington, and terminating at about Vancouver Island in British Columbia.

Mendocino Fracture Zone A fracture zone and transform boundary off the coast of Cape Mendocino in far northern California

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. It continues on west of its junction with the Gorda Ridge, as an inactive remnant section which extends for several hundred miles.

Gorda Ridge A tectonic spreading center off the northern coast of California and southern Oregon

The Gorda Ridge, a tectonic spreading center, is located roughly 200 kilometres (120 mi) off the northern coast of California and southern Oregon. Running NE – SW it is roughly 300 kilometres (190 mi) in length. The ridge is broken into three segments; the northern ridge, central ridge, and the southern ridge, which contains the Escanaba Trough.

Blanco Fracture Zone A right lateral transform fault zone between the Gorda Ridge and the Juan de Fuca Ridge in the nortwest Pacific

The Blanco Fracture Zone or Blanco Transform Fault Zone (BTFZ) is a right lateral transform fault zone, which runs northeast off the coast of Oregon in the Pacific Northwest of the United States, extending from the Gorda Ridge in the south to the Juan de Fuca Ridge in the north.

Queen Charlotte Fault

The Queen Charlotte Fault is an active transform fault that marks the boundary of the North American and the Pacific Plates. It is Canada's right-lateral strike-slip equivalent to the San Andreas Fault to the south in California. The Queen Charlotte Fault forms a triple junction on its south with the Cascadia subduction zone and the Explorer Ridge.

Explorer Ridge A mid-ocean ridge west of British Columbia, Canada

The Explorer Ridge is a mid-ocean ridge, a divergent tectonic plate boundary located about 241 km (150 mi) west of Vancouver Island, British Columbia, Canada. It lies at the northern extremity of the Pacific spreading axis. To its east is the Explorer Plate, which together with the Juan de Fuca Plate and the Gorda Plate to its south, is what remains of the once-vast Farallon Plate which has been largely subducted under the North American Plate. The Explorer Ridge consists of one major segment, the Southern Explorer Ridge, and several smaller segments. It runs northward from the Sovanco Fracture Zone to the Queen Charlotte Triple Junction, a point where it meets the Queen Charlotte Fault and the northern Cascadia subduction zone.

This is a list of articles related to plate tectonics and tectonic plates.

2010 Eureka earthquake

The 2010 Eureka earthquake occurred on January 9 at 4:27:38 pm PST offshore of Humboldt County, California, United States. The magnitude was measured 6.5 on the Mw scale, and its epicenter was located offshore in the Pacific Ocean 33 miles (53 km) west of the nearest major city, Eureka. Additionally, there was a separate earthquake further offshore of Eureka on February 4 with a slightly lower magnitude of 5.9. It was also the most significant earthquake in the Eureka area in terms of magnitude since the 1992 Cape Mendocino earthquakes. It was felt from Santa Cruz County, California in the south, to Eugene, Oregon in the north and to the east as far as Reno, Nevada.

1980 Eureka earthquake

The 1980 Eureka earthquake occurred on November 8 at 02:27:34 local time along the northern coastal area of California in the United States. With a moment magnitude of 7.3 and a maximum Mercalli intensity of VII, this strike-slip earthquake was the largest to occur in California in 28 years. Although damage was considered light, several loss estimates equaled or exceeded $2 million, and six injuries resulted when two vehicles came down with the partial collapse of a highway overpass on US 101 in Fields Landing. The north coast of California experiences frequent plate boundary earthquakes near the Mendocino Triple Junction and intraplate events also occur within the Gorda Plate.

1932 Eureka earthquake

The 1932 Eureka earthquake occurred on June 6 at 00:44:26 local time along the northern coastal area of California in the United States. With a moment magnitude of 6.4 and a maximum Mercalli intensity of VIII (Severe), this earthquake left one person dead from a falling chimney and several injured. The shock was the largest in the area since 1923 and was felt in southern Oregon and northern California.

References

  1. "Cape Mendocino". Geographic Names Information System . United States Geological Survey.
  2. California Department of Fish and Wildlife , California Protected Marine Areas, 14 March 2013
  3. California Department of Fish and Wildlife, Sugarloaf Island Special Closure, 2015
  4. Sugarloaf Island Special Closure Archived 2015-07-13 at the Wayback Machine , California Marine Sanctuary Foundation, accessed July 12, 2015
  5. Rowlett, Russ. "Northern California". Lighthouses of the United States. University of North Carolina at Chapel Hill. Retrieved 9 September 2012.
  6. USGS. "Cape Mendocino, California Earthquakes". Archived from the original on 2009-09-09. Retrieved 2009-10-21.
  7. Kathy Moley. "Why we have earthquakes: a unique geologic setting". Archived from the original on 2006-09-09. Retrieved 2009-10-21.