Editing Andes (section)

=== Seismic activity ===
Tectonic forces above the [[subduction zone]] along the entire west coast of South America where the [[Nazca Plate]] and a part of the [[Antarctic Plate]] are sliding beneath the [[South American Plate]] continue to produce an ongoing [[Orogeny|orogenic event]] resulting in minor to major [[earthquake]]s and [[volcanic eruption]]s to this day. Many high-magnitude earthquakes have been recorded in the region, such as the [[2010 Chile earthquake|2010 Maule earthquake]] (M8.8), the [[2015 Illapel earthquake]] (M8.2), and the [[1960 Valdivia earthquake]] (M9.5), which as of 2024 was the strongest ever recorded on seismometers.

The amount, magnitude, and type of seismic activity varies greatly along the subduction zone. These differences are due to a wide range of factors, including friction between the plates, angle of subduction, buoyancy of the subducting plate, rate of subduction, and hydration value of the mantle material. The highest rate of seismic activity is observed in the central portion of the boundary, between 33°S and 35°S. In this area, the angle of subduction is very low, meaning the subducting plate is nearly horizontal. Studies of mantle hydration across the subduction zone have shown a correlation between increased material hydration and lower-magnitude, more-frequent seismic activity. Zones exhibiting dehydration instead are thought to have a higher potential for larger, high-magnitude earthquakes in the future.<ref>{{Cite journal |last1=Rodriguez Piceda |first1=Constanza |last2=Gao |first2=Ya-Jian |last3=Cacace |first3=Mauro |last4=Scheck-Wenderoth |first4=Magdalena |last5=Bott |first5=Judith |last6=Strecker |first6=Manfred |last7=Tilmann |first7=Frederik |date=2023-03-17 |title=The influence of mantle hydration and flexure on slab seismicity in the southern Central Andes |journal=Communications Earth & Environment |language=en |volume=4 |issue=1 |page=79 |doi=10.1038/s43247-023-00729-1 |issn=2662-4435 |doi-access=free |bibcode=2023ComEE...4...79R}}</ref>

The mountain range is also a source of shallow intraplate earthquakes within the South American Plate. The largest such earthquake (as of 2024) [[1947 Satipo earthquake|struck Peru in 1947]] and measured {{M|s}} 7.5. In the Peruvian Andes, these earthquakes display normal ([[1946 Ancash earthquake|1946]]), strike-slip (1976), and reverse ([[1969 Huaytapallana earthquake|1969]], 1983) mechanisms. The Amazonian Craton is actively underthrusted beneath the sub-Andes region of Peru, producing thrust faults.<ref>{{cite journal |last1=Dorbath |first1=L. |last2=Dorbath |first2=C. |last3=Jimenez |first3=E. |last4=Rivera |first4=L. |title=Seismicity and tectonic deformation in the Eastern Cordillera and the sub-Andean zone of central Peru |journal=Journal of South American Earth Sciences |date=1991 |volume=4 |issue=1–2 |pages=13–24 |doi=10.1016/0895-9811(91)90015-D |bibcode=1991JSAES...4...13D |url=https://core.ac.uk/download/pdf/39863456.pdf}}</ref> In Colombia, Ecuador, and Peru, thrust faulting occurs along the sub-Andes due in response to contraction brought on by subduction, while in the high Andes, normal faulting occurs in response to gravitational forces.<ref name="Suárez83">{{cite journal |last1=Suárez |first1=Gerardo |last2=Molnar |first2=Peter |last3=Burchfiel |first3=B. Clark |title=Seismicity, fault plane solutions, depth of faulting, and active tectonics of the Andes of Peru, Ecuador, and southern Colombia |journal=Journal of Geophysical Research: Solid Earth |date=1983 |volume=88 |issue=B12 |pages=10403–10428 |doi=10.1029/JB088iB12p10403 |bibcode=1983JGR....8810403S}}</ref>

In the extreme south, a major [[transform fault]] separates [[Tierra del Fuego]] from the small [[Scotia Plate]].