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

Seismicity of the Earth 1900-2013, seismotectonics of South America (Nazca Plate Region)

2015 ◽  
Author(s):  
Gavin P. Hayes ◽  
Gregory M. Smoczyk ◽  
Harley M. Benz ◽  
Kevin P. Furlong ◽  
Antonio Villaseñor
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>

scholarly journals Specific Formation of the Bermuda and Dragon Triangles as a Result of a Change in the Axis of the Earth’s Rotation

2020 ◽  
pp. 19-25
Keyword(s):  
South America ◽  
Southeast Asia ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Axis Of Rotation ◽  
The Earth ◽  
Rotation Of The Earth ◽  
North And South America ◽  
North And South

The Bermuda Triangle is located in the area of the archipelago between North and South America and the Dragon Triangle is located in the area of the archipelago in Southeast Asia. There is a great resemblance between these two triangular areas; both were formed following special geological and tectonic conditions. It is herein proposed that their creation stems from the change in location of the axis of rotation of the earth and, accordingly, the change in the location of the equator.

The Relation of the Southern Trade Winds to Upwelling Processes During the Last 75,000 years

1977 ◽  
Vol 8 (3) ◽  
pp. 324-338 ◽  
Author(s):  
Adolfo Molina-Cruz
Keyword(s):  
Regression Analysis ◽  
South America ◽  
Deep Sea ◽  
Coastal Upwelling ◽  
Equatorial Pacific ◽  
The Other ◽  
Trade Winds ◽  
Equatorial Undercurrent ◽  
The Earth ◽  
Radiolarian Assemblages

In the equatorial Pacific, between the Galapagos Islands and the coast of South America, two kinds of upwelling of oceanic waters occur. One is related to coastal upwelling and the other to surfacing of the Equatorial Undercurrent. Both of those processes are associated with the development of the southeast trade winds blowing in this area. Coastal upwelling is increased when the trade winds are intensified, and the surfacing of the Equatorial Undercurrent occurs when the trades weaken. The development of coastal upwelling and the surfacing of the Equatorial Undercurrent are inferred from the radiolarian assemblages in the sediments. The abundance of quartz, opal, and radiolarian assemblages in the deep-sea sediments of this area, as well as the distance from the sample locations to land and to the quartz source, is correlated with the intensity of the trade winds (in February and August) through multiple regression analysis. The chronostratigraphy of core V19-29 (3°35′S, 83°56′W), used in this study, is inferred on basis of its δ180 record. During the last 75,000 years, the fluctuations in intensity of the trade winds have been concurrent with or preceded the fluctuations in the amount of ice stored on the continents. In general, the wind velocity of the winter trades has been intensified during cool climatic stages of the earth (δ180 stages 4 and 2) and they have been relaxed during warm stages (δ180 stages 3 and 1). Seasonal contrast of the trade winds has also fluctuated within time, having been relatively high during the upper part of δ180 stage 3.

scholarly journals Cadmium in Cacao: ‘From Soil to Bar’ the Journey of Cadmium at a Farm Level

2021 ◽  
Author(s):  
Daniel Bravo ◽  
Margareth Santander ◽  
Jader Rodríguez ◽  
Sebastian Escobar
Keyword(s):  
South America ◽  
Soil Properties ◽  
Anthropogenic Activities ◽  
Farm Level ◽  
Post Harvest ◽  
The Earth

Abstract Cadmium (Cd) is a non-nutritive element present across the earth. In cacao crops from South America, Cd has become one of the biggest challenges due to its flux from soils, and due to the enriched content of this metal, it makes its way into the beans and finally affects the chocolate quality. This manuscript aims to show how the flux of Cd occurs, from the soil to the post-harvest phase and chocolate production, by analysing the possible inputs to the system in a single farm assessed as a model for enriched-Cd status. This study shows that both geogenic and anthropogenic activities have an incidence on the final Cd content in chocolate, especially with respect to soil properties, fertiliser applications, post-harvest treatments and chocolate production.

scholarly journals SHOCK METAMORPHISM IN VOLCANIC ROCK DUE TO THE IMPACT OF THE MIGUIR-CAJAS METEORITE IN 1995 AND ITS IMPORTANCE FOR ECUADOR

2021 ◽  
Vol 35 (2) ◽  
pp. 315-321
Author(s):  
Theofilos TOULKERIDIS ◽  
◽  
Richard Caleb ECHEGARAY-AVEIGA ◽  
Karen Paola MARTINEZ-MALDONADO ◽  
◽  
...  
Keyword(s):  
South America ◽  
Volcanic Rock ◽  
Shock Metamorphism ◽  
Tourist Attraction ◽  
The Past ◽  
The Earth ◽  
The Impact ◽  
Extraterrestrial Material

In the past of the earth several asteroids and meteoroids have been impacted, but most of these collisions have been eroded and today there are only sometimes direct and indirect indications, such as massive extinctions of species in the form of fossils, layers with content of extraterrestrial material among others. Based on our recent reconnaissance in the field in 2017, we have been able to identify a new impact of a meteorite on volcanic rock of the Miocene Tarqui Formation in central Ecuador. We were able to reveal and reconstruct the corresponding trajectory as well as its impact day being in 1995. Based on known impacts in South America, this is the very first to have been impacted on rocks, which would lead to a clear shock metamorphism. This discovery of the impact on a rock may soon be a major tourist attraction of the country due to its accessibility and importance for being unique in Ecuador and on the continent.

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