Rivera Plate

The Rivera Plate is a small tectonic plate (a microplate) located off the west coast of Mexico, just south of the Baja California Peninsula. It is bounded on the northwest by the East Pacific Rise, on the southwest by the Rivera Transform Fault, on the southeast by a deformation zone, and on the northeast by the Middle America Trench and another deformation zone.

The Rivera Plate is believed to have separated from the Cocos Plate located to its southeast about 5–10 million years ago. Seismicity and tomography images show that the Rivera plate dips at 40° beneath the forearc region and then dips ~70° beneath the Trans-Mexican Volcanic Belt. The subduction of the Rivera Plate under the North American Plate, in the Mid-American Trench, has been the cause of the strongest earthquakes in the history of Mexico, including the largest earthquake in Mexico during the 20th century which occurred on June 3, 1932 in the state of Jalisco. The quake had a magnitude of 8.2 with a magnitude 7.8 aftershock, both of which caused widespread casualties and damage.

On October 9, 1995, a magnitude 7.6 earthquake occurred beneath the Jalisco region and caused significant loss of life and property.

A 7.8 magnitude earthquake occurred on January 24, 2003 near Colima in Mexico.

Rivera Plate
The Rivera Plate
TypeMinor
Approximate area730,000 km2[1]
Movement1north-west
Speed114mm/year
FeaturesPacific Plate
1Relative to the African Plate
Tectonic setting western Mexico
Plate boundaries in the Pacific, offshore western Mexico

See also

  • Farallon Plate – An ancient oceanic plate that has mostly subducted under the west coast of the North American Plate
  • Juan de Fuca Plate – A small tectonic plate in the eastern North Pacific
  • Rivera Triple Junction – Place where the North American Plate, the Rivera Plate, and the Pacific Plate meet

References

  1. ^ http://geology.about.com/library/bl/blplate_size_table.htm
1932 Jalisco earthquakes

The 1932 Jalisco earthquakes began on June 3 at 10:36 UTC with a megathrust event that registered 8.2 on the moment magnitude scale. With a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale, at least 400 deaths were caused in Mexico and neighboring Guatemala. It was the first of a series of seismic events that affected parts of western Mexico during the month of June 1932, all reaching magnitude 7 or greater.The Mexican subduction zone, the Middle America Trench, is seismically active and has generated both destructive and non-destructive tsunamis. Each earthquake in the series caused significant damage, injuries, and deaths, and in each case tsunamis of various heights were generated, with the June 22 catastrophic tsunami in Cuyutlán and San Blas being described as one of the most destructive events in the region based on all available historical records.

1981 Playa Azul earthquake

The 1981 Playa Azul earthquake occurred on October 24, 1981, at 21:22 local time (03:22 UTC on October 25). It was located near Playa Azul, Michoacán, Mexico. The magnitude of the earthquake was Mw 7.2, or Ms 7.3. Three deaths were reported, two from Michoacán and one from Mexico City. Some buildings were damaged in both Michoacán and Mexico City. A small tsunami was registered in Acapulco with a maximum height of 9 cm.

1995 Colima–Jalisco earthquake

The 1995 Colima–Jalisco earthquake occurred on October 9 at 15:35 UTC with a moment magnitude of 8.0 and a maximum Mercalli intensity of VIII (Severe). The shock occurred off the coast of Jalisco, Mexico, where a tsunami was triggered that affected a 200 km (120 mi) stretch of the coast. The earthquake could be felt in Mexico City and in high-rise buildings in Dallas and Houston. In Mexico, the Cihuatlan-Manzanillo was the most severely affected area. At least 49 people died and 100 were injured.

2003 Colima earthquake

The 2003 Colima earthquake occurred on 21 January with a moment magnitude of 7.5 and a maximum Mercalli intensity of VIII (Severe). The epicenter was located on the Pacific coast in the Mexican state of Colima. The earthquake was felt as far away as Mexico City and in southern parts of the United States.

Cocos Plate

The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it. The Cocos Plate was created approximately 23 million years ago when the Farallon Plate broke into two pieces, which also created the Nazca Plate. The Cocos Plate also broke into two pieces, creating the small Rivera Plate. The Cocos Plate is bounded by several different plates. To the northeast it is bounded by the North American Plate and the Caribbean Plate. To the west it is bounded by the Pacific Plate and to the south by the Nazca Plate.

East Pacific Rise

The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from (north to south) the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near 55° S, 130° W, where it joins the Pacific-Antarctic Ridge trending west-southwest towards Antarctica, near New Zealand (though in some uses the PAR is regarded as the southern section of the EPR). Much of the rise lies about 3200 km (2000 mi) off the South American coast and rises about 1,800–2,700 m (6,000–9,000 ft) above the surrounding seafloor.

Geology of the Pacific Ocean

The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.The tectonic plates continue to move today. The slowest spreading ridge is the Gakkel Ridge on the Arctic Ocean floor, which spreads at less than 2.5 cm/year (1 in/year), while the fastest, the East Pacific Rise near Easter Island, has a spreading rate of over 15 cm/year (6 in/year).

List of tectonic plates

This is a list of tectonic plates on the Earth's surface. Tectonic plates are pieces of Earth's crust and uppermost mantle, together referred to as the lithosphere. The plates are around 100 km (62 mi) thick and consist of two principal types of material: oceanic crust (also called sima from silicon and magnesium) and continental crust (sial from silicon and aluminium). The composition of the two types of crust differs markedly, with mafic basaltic rocks dominating oceanic crust, while continental crust consists principally of lower-density felsic granitic rocks.

Mascota volcanic field

Mascota volcanic field is a volcanic field in Mexico. It is formed by cinder cones and lava domes that lie 50 kilometres (31 mi) east of Puerto Vallarta. Several other volcanic fields lie in the neighbourhood.

Volcanism in the Mascota volcanic field occurs within a complicated tectonic context. The Jalisco block is bordered by two rift zones and one subduction zone.

The Mascota volcanic field is the youngest occurrence of minettes identified on Earth, with the most recent dates being about 70,000 ± 80,000 years ago. The youngest eruption of the field may have occurred less than 5,600 years ago.

Outline of plate tectonics

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

Pacific-Farallon Ridge

The Pacific-Farallon Ridge was a spreading ridge during the late Cretaceous that extended 10,000 km in length and separated the Pacific Plate to the west and the Farallon Plate to the east. It ran south from the Pacific-Farallon-Kula triple junction at 51°N to the Pacific-Farallon-Antarctic triple junction at 43°S. As the Farallon Plate subducted obliquely under the North American Plate, the Pacific-Farallon Ridge approached and eventually made contact with the North American Plate about 30 million years ago. On average, this ridge had an equatorial spreading rate of 13.5 cm per year until its eventual collision with the North American Plate. In present day, the Pacific-Farallon Ridge no longer formally exists since the Farallon Plate has been broken up or subducted beneath the North American Plate, and the ridge has segmented, having been mostly subducted as well. The most notable remnant of the Pacific-Farallon Ridge is the 4000 km Pacific-Nazca segment of the East Pacific Rise.

RISE project

The RISE Project (Rivera Submersible Experiments) was a 1979 international marine research project which mapped and investigated seafloor spreading in the Pacific Ocean, at the crest of the East Pacific Rise (EPR) at 21° north latitude. Using a deep sea submersible (ALVIN) to search for hydrothermal activity at depths around 2600 meters, the project discovered a series of vents emitting dark mineral particles at extremely high temperatures which gave rise to the popular name, "black smokers". Biologic communities found at 21° N vents, based on chemosynthesis and similar to those found at the Galapagos spreading center, established that these communities are not unique. Discovery of a deep-sea ecosystem not based on sunlight spurred theories of the origin of life on Earth.

Rivera Transform Fault

The Rivera Transform Fault, also referred to as the Rivera Fracture Zone, is a right lateral-moving (dextral) transform fault which lies along the seafloor of the Pacific Ocean off the west coast of Mexico just south of the mouth of the Gulf of California. It runs between two segments of the East Pacific Rise, forming the southwest boundary of the small Rivera Plate. The fault is broken into two segments, bisected by a short rifting zone.

Rivera Triple Junction

The Rivera Triple Junction (RTJ) is a geologic triple junction located on the seafloor of the Pacific Ocean southeast of the southern tip of the Baja California Peninsula. At the RTJ, three tectonic plates intersect: the North American Plate, the Rivera Plate, and the Pacific Plate. The triple junction is often referenced as the southern counterpart of the Mendocino Triple Junction, but it is not as well understood. One research effort describes it as an R-R-R (ridge-ridge-ridge) type junction which lies along the segment of the East Pacific Rise which runs between the Rivera Transform Fault and the Tamayo Fault, although the third axis of the junction is not clearly defined. Part of the problem in describing the Rivera Triple Junction is that if it were truly analogous to the Mendocino Triple Junction, then it would exist at the junction of the East Pacific Rise, the Tamayo Fault, and the Middle America Trench. But thus far, there does not appear to be any evidence that the Tamayo Fault or the East Pacific Rise intersect the Middle America Trench at all, thus presenting a possible example of a diffuse triple junction.

San Andreas Fault

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 (0.79 to 1.38 in)/yr.The fault was identified in 1895 by Professor Andrew Lawson of UC Berkeley, who discovered the northern zone. It is often described as having been named after San Andreas Lake, a small body of water that was formed in a valley between the two plates. However, according to some of his reports from 1895 and 1908, Lawson actually named it after the surrounding San Andreas Valley. Following the 1906 San Francisco earthquake, Lawson concluded that the fault extended all the way into southern California.

In 1953, geologist Thomas Dibblee concluded that hundreds of miles of lateral movement could occur along the fault. A project called the San Andreas Fault Observatory at Depth (SAFOD) near Parkfield, Monterey County, was drilled through the fault during 2004–2007 to collect material and make physical and chemical observations to better understand fault behavior.

Trans-Mexican Volcanic Belt

The Trans-Mexican Volcanic Belt (Spanish: Eje Volcánico Transversal), also known as the Transvolcanic Belt and locally as the Sierra Nevada (Snowy Mountain Range), is a volcanic belt that covers central-southern Mexico. Several of its highest peaks have snow all year long, and during clear weather, they are visible to a large percentage of those who live on the many high plateaus from which these volcanoes rise.

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Tectonic plates of Central America (Pacific PlateNorth American PlateCaribbean Plate Convergence Zone)
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