Tectonics of the Nazca plate and the continental margin of western South America, 18°S to 23° S

1981 ◽  
pp. 587-618 ◽  
Author(s):  
William T. Coulbourn
Keyword(s):  
South America ◽  
Continental Margin ◽  
Nazca Plate

Seismicity of the Earth 1900-2007, Nazca Plate and South America

2010 ◽  
Author(s):  
Susan Rhea ◽  
Gavin P. Hayes ◽  
Antonio H. Villaseñor ◽  
Kevin P. Furlong ◽  
Arthur C. Tarr ◽  
...  
Keyword(s):  
South America ◽  
Nazca Plate ◽  
The Earth

Ground-motion model for subduction earthquakes in northern South America

2021 ◽  
pp. 875529302110275
Author(s):  
Carlos A Arteta ◽  
Cesar A Pajaro ◽  
Vicente Mercado ◽  
Julián Montejo ◽  
Mónica Arcila ◽  
...  
Keyword(s):  
South America ◽  
Ground Motion ◽  
Ground Motions ◽  
Strong Motion ◽  
Motion Prediction ◽  
Depth Range ◽  
Ground Motion Prediction ◽  
Natural Period ◽  
Nazca Plate ◽  
Northern South America

Subduction ground motions in northern South America are about a factor of 2 smaller than the ground motions for similar events in other regions. Nevertheless, historical and recent large-interface and intermediate-depth slab earthquakes of moment magnitudes Mw = 7.8 (Ecuador, 2016) and 7.2 (Colombia, 2012) evidenced the vast potential damage that vulnerable populations close to earthquake epicenters could experience. This article proposes a new empirical ground-motion prediction model for subduction events in northern South America, a regionalization of the global AG2020 ground-motion prediction equations. An updated ground-motion database curated by the Colombian Geological Survey is employed. It comprises recordings from earthquakes associated with the subduction of the Nazca plate gathered by the National Strong Motion Network in Colombia and by the Institute of Geophysics at Escuela Politécnica Nacional in Ecuador. The regional terms of our model are estimated with 539 records from 60 subduction events in Colombia and Ecuador with epicenters in the range of −0.6° to 7.6°N and 75.5° to 79.6°W, with Mw≥4.5, hypocentral depth range of 4 ≤  Zhypo ≤ 210 km, for distances up to 350 km. The model includes forearc and backarc terms to account for larger attenuation at backarc sites for slab events and site categorization based on natural period. The proposed model corrects the median AG2020 global model to better account for the larger attenuation of local ground motions and includes a partially non-ergodic variance model.

Slab tearing of the Nazca plate in the Central Andes and its interaction with the overriding plate

2021 ◽  
Author(s):  
Nipaporn (Nidnueng) Nakrong ◽  
Wim Spakman ◽  
Fangqin Chen ◽  
Gordon Lister
Keyword(s):  
Structural Geology ◽  
South America ◽  
Seismic Tomography ◽  
Strike Slip ◽  
Surface Structures ◽  
Nazca Plate ◽  
Tectonic Reconstruction ◽  
Subducting Plate ◽  
Slab Tearing ◽  
Subduction System

<p>Slab tearing in subducting plates is widely implicated in terms of the factors that control the evolution of the structural geology of the over-riding crust, here illustrated by interactions between the subducting Nazca plate and the overlying overthrust western continental margin of South America. We examine the different ways that structures above the bounding megathrusts are linked to the ripping and tearing of the subducting plate beneath, in particular focussed on the Andean orogeny at the Arica bend during the formation of the Bolivian orocline. We can create models for slab tearing by integrating seismotectonic analysis, seismic tomography, and morphotectonics. There are many features in the UU-P07 tomographic model that we cannot yet relate to the evolution of surface structure, for example, the gaps and tears beneath the Bolivian Orocline, or the separation of the detached slab we interpret as a paleo-segment of the Nazca plate, illustrating traces of an ancient subduction system. However, we can link the evolution of some surface structures to the growth of the giant kink of the Nazca slab that connects to the surface near the Arica bend. This may have driven strike-slip faulting with opposing sense-of-shear, northern south of the Bolivian Orocline. Megathrust rupture segments may be related to the polygonal kinked trace of the orogen, which is not at all a continuously curved arc. In this contribution, we relate the growth and accentuation of the Arica Bend to the evolution of the giant kink in the Nazca plate using a 4-D tectonic reconstruction.</p>

Anorogenic magmatism and the Grenvillian Orogeny

1989 ◽  
Vol 26 (3) ◽  
pp. 479-489 ◽  
Author(s):  
Brian F. Windley
Keyword(s):  
United States ◽  
South America ◽  
Continental Margin ◽  
South Atlantic ◽  
Island Arc ◽  
The South ◽  
The West ◽  
Continental Block ◽  
Grenvillian Orogeny ◽  
Alkaline Complexes

The Grenvillian Orogeny was preceded by extensive anorogenic volcanism and plutonism in the period 1500–1300 Ma in the form of rhyolites, epizonal granites, anorthosites, gabbros, alkaline complexes, and basic dykes. An analogue for the mid-Proterozoic anorogenic complexes is provided by the 2000 km by 200 km belt of anorogenic complexes in the Hoggar, Niger, and Nigeria, which contain anorthosites, gabbros, and peralkaline granites and were generated in a Cambrian to Jurassic rift that farther south led to the formation of the South Atlantic. An analogue for the 1 × 106 km2 area of 1500–1350 Ma rhyolites (and associated epizonal granites) that underlie the mid-continental United States is provided by the 1.7 × 106 km2 area of Jurassic Tobifera rhyolites in Argentina, which were extruded on the stretched continental margin of South America immediately preceding the opening of the South Atlantic. The mid-Proterozoic complexes were intruded close to the continental margin of the Grenvillian ocean and were commonly superimposed by the craton-directed thrusts that characterized the final stages of the Grenvillian Orogeny. The bulk of the Keweenawan rift and associated anorogenic magmatism formed about 1100 Ma at the same time as the Ottawan Orogeny in Ontario, which probably resulted from the collision of the island arc of the Central Metasedimentary Belt attached to the continental block in the east with the continental block to the west. The most appropriate modern equivalent would be the Rhine Graben, which formed at the same time as the main Alpine compression.

Surface sediments of the Peru-Chile continental margin and the Nazca plate

1980 ◽  
Vol 91 (6) ◽  
pp. 321 ◽  
Author(s):  
LAWRENCE A. KRISSEK ◽  
KENNETH F. SCHEIDEGGER ◽  
LAVERNE D. KULM
Keyword(s):  
Continental Margin ◽  
Surface Sediments ◽  
Nazca Plate
Sign in / Sign up

Export Citation Format

Share Document