BRAZIL AND PLATE TECTONICS  BY LINDA POTTER

 

 

Brazil and Plate Tectonics

 

Continental Drift is one area that the South American plate comes is used to prove this theory.  As animals in Brazil and Africa seem to have a common ancestor.  Another place the plates are used are to explain the Andes Mountains that separate Brazil from the other countries on South American continent.  Below is a map and information of the Drift found in Wikipedia the free online encyclopedia.

 

The South American Plate (Dutch: Zuid-Amerikaanse Plaat, French: Plaque Sud-américaine, Portuguese: Placa Sul-Americana, Spanish: Placa Sudamericana) is a tectonic plate which includes the continent of South America and also a sizeable region of the Atlantic Ocean seabed extending eastward to the Mid-Atlantic Ridge.

The easterly side is a divergent boundary with the African Plate forming the southern part of the Mid-Atlantic Ridge. The southerly side is a complex boundary with the Antarctic Plate and the Scotia Plate. The westerly side is a convergent boundary with the subducting Nazca Plate. The northerly side is a boundary with the Caribbean Plate and the oceanic crust of the North American Plate. At the Chile Triple Junction in Taitato-Tres Montes Peninsula, an oceanic ridge — the Chile Rise — is subducting under the South American plate.

The South American Plate is in motion, moving westward away from the Mid-Atlantic Ridge. The eastward-moving and more dense Nazca Plate is subducting under the western edge of the South American Plate along the Pacific coast of the continent at a rate of 77 mm per year.[1] This collision of plates is responsible for lifting the massive Andes Mountains and causing the volcanoes which are strewn throughout them.

 

Another Article I Found Interesting

 

Brazil sits on the South American plate and it moves along with it and natural disasters are caused by the movement and other factors that Brazil faces.  The following is from a Disasters Management book for Brazil.

Natural Disaster Management

in the Brazilian Amazon:

An Analysis of the States

of Acre, Amazonas and Pará

By Claudio F. SzlafszteinCenter of Environmental Sciences (NUMA),

Federal University of Pará,

Brazil (paragraph taken in section 20

Considering the different variables that correspond to the risk management issues in the Amazon region, some initial reflections should be established in order to develop better studies and analyses.  The Brazilian Amazon region is a heterogeneous territory divided into 6 states and 310 municipalities. According to the Brazilian Institute of Geography and Census (IBGE, 2011), the Amazon region occupies an area of 3.575.951 km², representing approximately 40% of Brazil and, its population of 14.481.009 inhabitants an 8% of the total population of the country. Although the intense activities natural resources exploration, yet 62% of the area maintain its forest original cover, and around 20% is already impacted. Many of the forests and traditional villages are protected by conservation units (around 390) and indigenous

Amazonas and Pará (highlighted).

The main risks in the Amazon region are caused by natural and social hazards, with the technological hazards in a few urban areas (e.g., Barcarena, Belém and Manaus). Among the first, floods and drought of the main rivers are described with recurrent consequences in urban areas (e.g., Rio Branco, Manaus), in the Western region of the State of Acre and small towns at the margins of the Amazonas, Tocantins and Xingu Rivers. To a lesser extent, strong whirlwind, localized processes of fluvial erosion, and seismicity reflection of Andean tectonic conditions also could be depicted. Social risks are mainly related to the extensive and intense process of deforestation. Natural or social forests burning risk shows the simultaneous loss of biodiversity and infrastructure in areas of close proximity to road systems (Szlafsztein, 2003; Eger and Aquino, 2006; Maia et al., 2008)

Fig. 2. Population living in natural risk prone areas in urban areas of the Amazon region.

Left - Mass movement in Novo Repartimento (state of Pará), and right – Flood in

Parauapebas (state of Pará).

 

 

 

 

In my research the following article was found:

 

HOT ROCK DEEP BENEATH BRAZIL SHAKES GEOLOGICAL THEORY ABOUT PLATE TECTONICS

 

By William J. Broad, New York Times News Service

Published: Sunday, Nov. 19 1995 12:00 a.m. MST

Summary

Deep beneath Brazil, a mysterious plume of hot rock extending hundreds of miles into the Earth's interior has been discovered and is raising questions about a central tenet of geological theory.
The theory of plate tectonics holds that the Earth's surface is made up of a dozen or so crustal plates that float on a sea of molten rock whose currents have set continents adrift over the ages. The new finding, however, suggests that the plates and the underground molten sea are not always independent.

Deep beneath Brazil, a mysterious plume of hot rock extending hundreds of miles into the Earth's interior has been discovered and is raising questions about a central tenet of geological theory.

The theory of plate tectonics holds that the Earth's surface is made up of a dozen or so crustal plates that float on a sea of molten rock whose currents have set continents adrift over the ages. The new finding, however, suggests that the plates and the underground molten sea are not always independent.Scientists from Brazil and the United States report on the discovery in the current issue of the journal Nature.

The authors are John C. VanDecar and David E. James of the Carnegie Institution of Washington, and Marcelo Assumpcao of the University of Sao Paulo. The Carnegie Institution runs a project to study Brazil's deep geology with the university.

The basis for the discovery was laid in late 1992 when the researchers began setting up portable seismic units across southeastern Brazil. Seismometers sunk into firm rock can measure faint vibrations from distant earthquakes, and networks of them can provide clues about geological structures deep beneath the Earth's surface.

As data came in over the years, the team was surprised to find evidence of a large plume of very hot rock that extended deep beneath the region, going down at least 370 miles. This deep area between the crust and the core is called the mantle and is usually characterized by molten rock. The plume was much hotter.

"We were shocked," VanDecar said in an interview. "That's why you have to go out and look around in interesting areas to see what you're going to find."

The puzzling feature was located beneath the great Parana volcanic flood plain, one of the regions of the Earth where hot lava once gushed out in titanic upheavals that sometimes dwarfed by many thousand times the volume of ordinary volcanic eruptions.

 

 

Work Cited:

Bond, William J., HOT ROCK DEEP BENEATH BRAZIL SHAKES GEOLOGICAL THEORY ABOUT PLATE TECTONICS.  New York Times News Service 

Published: Sunday, Nov. 19 1995 12:00 a.m. MST, www.nytimes.com/.../hot-rock-deep-beneath-brazil-shakes-a-geological-the...

Claudio F. Szlafsztein (2012). Natural Disaster Management in the Brazilian Amazon: An Analysis of the States

of Acre, Amazonas and Pará, Natural Disasters, Dr. Sorin Cheval (Ed.), ISBN: 978-953-51-0188-8, InTech,

Available from: http://www.intechopen.com/books/natural-disasters/natural-disasters-management-in-thebrazilian-

amazon-an-analysis-of-the-states-of-acre-amazonas-and

 

Jump up ^ Pisco, Peru, Earthquake of August 15, 2007: Lifeline Performance. Reston, VA: ASCE, Technical Council on Lifeline Earthquake Engineering. ISBN 9780784410615.

Wikipedia