Rivera plate
The Riveraplatte is a tectonic plate , under the Pacific Ocean between the southern tip of Baja California (Baja California) and the West coast of Mexico is located. With an area of around 730,000 km², it belongs to the microplates .
description
The Rivera Plate is located on the eastern edge of the Pacific Ocean between the North American Plate in the north to east, the Cocos Plate in the southeast and the Pacific Plate in the southwest to west.
The existence of the plate was first suggested by Tanya Atwater in 1970 . Its kinematic independence from the surrounding plates was subsequently confirmed by several authors.
The plate, made up of oceanic lithosphere, covers an area of 730,000 square kilometers or 0.00249 steradians . Its Euler pole of rotation is given by Bird (2003) as 26.7 ° N and 105.2 ° W, around which the plate rotates at 4.6923 ° / Ma (with the Pacific plate as reference).
The plate is created on the Rivera Ridge , a northwestern continuation of the East Pacific Ridge . The sea ridge separates the microplate from the Pacific plate to the northwest. The Rivera transform zone - a transform fault along which the east Pacific ridge is displaced to the northwest - forms its southwest boundary. In the southeast, it meets the coconut plate along a diffuse deformation zone. In the northeast it meets the Central America Trench , in which it is subducted under the North American Plate, and the Tamayo Fracture Zone , another deformation zone that separates it from the Gulf of California .
It is believed that the Rivera plate separated from the coconut plate at the latest at the beginning of the Pliocene 5 million years ago. Your sense of movement is directed to the northwest at a speed of 14 millimeters / year - much slower than the Pacific plate, which moves in the same direction at 76 millimeters / year, and also slower than the Mexican mainland, which has the same trend at 25 millimeters / year follows.
The Rivera plate, together with the coconut plate, the Nazca plate , the Juan de Fuca plate , the Explorer plate and the Gorda plate, represent a remnant from the disintegration of the Farallon plate , which from the Jura almost entirely under the North American and South American continents was subducted.
Subduction
On the basis of seismic tomography it was possible to determine that the Rivera plate dips below the forearc of the Central America Trench at an angle of incidence of 40 ° and then steepens to 70 ° below the Sierra Volcánica Transversal . The subducted oceanic crust here is around 9 million years old and therefore dates from the late Miocene ( Tortonian ).
earthquake
The subduction of the Rivera plate is by no means aseismic, but is responsible for very destructive earthquakes in Mexico, including the strongest earthquake of the 20th century in Mexico on June 3, 1932 in the state of Jalisco . The quake reached a magnitude of 8.2 with an aftershock of 7.8. Both quakes claimed numerous lives and caused great damage. On October 9, 1995, a magnitude 7.6 earthquake occurred under Jalisco, which also claimed many victims and caused major property damage. The series of earthquakes continued in the 21st century as well. On January 24, 2003, an earthquake with a magnitude of 7.8 occurred near Colima .
See also
literature
- C. DeMets, I. Carmichael, T. Melbourne, O. Sanchez, J. Stock, G. Suarez, K. Hudnut: Anticipating the Successor to Mexico's Largest Historical Earthquake . In: Earth in Space . Vol. 8, No. 5, 1996, pp. 6 .
- Charles DeMets, Stephen Traylen: Motion of the Rivera plate since 10 Ma relative to the Pacific and North American plates and the mantle . In: Tectonophysics . 318, Issues 1-4, 2000, pp. 119-159 .
- Yang et al .: Seismic structure beneath the Rivera subduction zone from finite-frequency seismic tomography . In: Solid Earth . 114, Issue B 1, 2009, p. 1-12 .
Individual evidence
- ^ T. Atwater: Implications of plate tectonics for the Cenozoic tectonic evolution of western North America . In: Geological Society of America Bulletin . tape 81 , 1970, pp. 3513-3536 .
- ↑ C. DeMets, S. Stein: Present-day kinematics of the Rivera plate and implications for tectonics in southwestern Mexico . In: Journal of Geophysical Research . tape 95 , 1999, pp. 21, 931, 948 .
- ↑ Charles DeMets, Stephen Traylen: Motion of the Rivera plate since 10 Ma relative to the Pacific and North American plates and the mantle . In: Tectonophysics . 318, Issues 1-4, 2000, pp. 119-159 .
- ↑ P. Bird: An updated digital model of plate boundaries . In: Geochemistry Geophysics Geosystems . tape 4 (3) , 2003, pp. 1-52 , doi : 10.1029 / 2001GC000252 .
- ↑ Mario Pardo, Gerardo Suarez: Steep subduction geometry of the Rivera plate beneath the Jalisco block in western Mexico . In: Geophysical Research Letters . vol. 20, no.21, 1993, p. 2391-2394 .
- ↑ K. Klitgord, J. Mammerickx: Northern East Pacific Rise: Magnetic anomaly and bathymetric framework . In: Journal of Geophysical Research . tape 87 , 1982, pp. 6725-6750 .
- ↑ SK Singh et al .: The great Jalisco, Mexico, earthquake of 1932: Subduction of the Rivera Plate . In: Bulletin of the Seismological Society of America . tape 75 , 1985, pp. 1301-1313 .