Nazca Plate
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robot Adding: [[it:Placca di Nazca]]
[[Image:Plates tect2 en.svg|thumb|right|300px|{{legend|#CCE7F0|The Nacza plate, shown in light blue|border=#000 solid 1px}}]]
The '''Nazca Plate''', named after the [[Nazca]] region of southern [[Peru]], is an oceanic [[tectonic plate]] in the eastern [[Pacific Ocean]] basin off the west coast of [[South America]].
The eastern margin is a [[convergent boundary]] [[subduction zone]] under the [[South American Plate]] and the [[Andes Mountains]], forming the [[Peru-Chile Trench]]. The southern side is a [[divergent boundary]] with the [[Antarctic Plate]], the [[Chile Rise]], where [[seafloor spreading]] permits [[magma]] to rise. The western side is a divergent boundary with the [[Pacific Plate]], forming the [[East Pacific Rise]]. The northern side is a divergent boundary with the [[Cocos Plate]], the [[Galapagos Rise]]. A [[triple junction]] occurs at the northwest corner of the plate where the Nazca, the Cocos, and the Pacific plates all join off the coast of [[Colombia]].
A second junction, the [[Chile Triple Junction]], occurs at the southwest corner at the intersection with the Nazca, the Pacific, and the Antarctic plates off the coast of southern [[Chile]]. At each of these triple junctions an ''anomalous'' microplate exists, the Galapagos Microplate at the northern junction and the Juan Fernandez Microplate at the southern junction. The Easter Island Microplate is a third microplate that is located just north of the Juan Fernandez Microplate and lies just west of [[Easter Island]].
Yet another triple junction, the [[Chile Triple Junction]],<ref>http://www.nsm.buffalo.edu/courses/gly481-581/McGuire05_2.pdf Tectonics of South America: Chile Triple Junction</ref> occurs on the seafloor of the [[Pacific Ocean]] off [[Taitao Peninsula|Taitao]] and [[Tres Montes Peninsula]] at the southern coast of [[Chile]]. Here three [[tectonics|tectonic]] plates meet: the Nazca Plate, the [[South American Plate]], and the [[Antarctic Plate]]. This triple junction is unusual in that it consists of a [[mid-oceanic ridge]], the [[Chile Rise]], being [[subducted]] under the South American Plate at the [[Peru-Chile Trench]]. This triple junction has been considered to be related to the [[moment magnitude]] 9.5, 1960 [[megathrust earthquake]] known as the [[Great Chilean Earthquake]].
Luckily, very few islands are there to suffer the earthquakes that are a result of complicated movements at these junctions. [[Juan Fernández Islands]] is an exception.
The '''Carnegie Ridge''' is a 1350-km-long and up to 300-km-wide feature on the ocean floor of the northern Nazca Plate that includes the [[Galápagos Islands|Galápagos archipelago]] at its western end. It is being subducted under South American with the rest of the Nazca Plate.
The absolute motion of the Nazca Plate has been calibrated at 3.7 cm/yr east motion (88°), some of the fastest absolute motion of any tectonic plate. The subducting Nazca Plate, which exhibits unusual [[flat-slab subduction]], is tearing as well as deforming as it is subducted (Barzangi and Isacks) has formed, and continues to form the [[volcano|volcanic]] [[Andes]] Mountain Range. Deformation of the Nazca Plate even affects the geography of [[Bolivia]], far to the east (Tinker et al.).
The precursor of the Nazca Plate and the Cocos Plate to its north was the [[Farallon Plate]], which split in late [[Oligocene]] times, about 22.8 My, a date arrived at by interpreting [[Geomagnetism|magnetic anomalies]].
==Notes==
{{reflist}}
==References==
*[http://www.extremescience.com/PlateTectonicsmap.htm Extreme Science site: "A Lesson in Plate tetonics"] The basics explained.
*[http://www.earth.columbia.edu/news/2002/story12-05-02.html Galapagos rise junction (map)]
*[http://www.pmel.noaa.gov/vents/s-epr.html Juan Fernandez and Easter microplate (map)]
*Muawia Barazangi and Bryan L. Isacks, "Spatial distribution of earthquakes and subduction of the Nazca plate beneath South America" in ''Geology'' Vol. 4, No. 11, pp. 686–692. [http://www.gsajournals.org/gsaonline/?request=get-abstract&doi=10.1130%2F0091-7613(1976)4%3C686:SDOEAS%3E2.0.CO%3B2 Abstract]
*Mark Andrew Tinker, Terry C. Wallace, Susan L. Beck, Stephen Myers, and Andrew Papanikolas, "Geometry and state of stress of the Nazca plate beneath Bolivia and its implication for the evolution of the Bolivian orocline" in ''Geology'' '''24'''(5), pp. 387–390 [http://www.gsajournals.org/gsaonline/?request=get-abstract&doi=10.1130%2F0091-7613(1996)024%3C0387:GASOSO%3E2.3.CO%3B2 Abstract]
*Cahill, T. and B. Isacks (1992). "Seismicity and shape of the subducted Nazca plate." ''Journal Geophysical Research'' '''97''' (12)
*James, D. (1978). "Subduction of the Nazca plate beneath Central Peru." ''Geology'' '''6''' (3) pp 174 – 178
*[http://www-odp.tamu.edu/publications/170_SR/VOLUME/CHAPTERS/SR170_07.PDF Martin Meschede and Udo Barckhausen, "Plate tectonic evolution of the Cocos-Nazca spreading center"] (pdf file)
{{Tectonic plates}}
[[Category:Tectonic plates]]
[[Category:Geology of Chile]]
[[Category:Natural history of South America]]
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