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| Landslides: very common in Rio de Janeiro, Brazil http://s2.dmcdn.net/bP11/x240-8pi.jpg |
In the last unit sections of class lectures, we talked about rock decays and weathering and how hydrology changes everything in the environment. The most common activity in Rio de Janeiro, Brazil are landslides. The key to landslides and all of the downslope movement of angular slope material is gravity. Gravity and landslides are rapid forms of mass wasting. Any object on earth's surface involves gravity. The type of mass wasting most common in Rio is an avalanche style fall. Normally when we see the word avalanche we think snow. But the term avalanche really means a rapid down flow of any type of object. Debris, rocks, mudflow. It basically means a change in flow that incorporates colluvium.
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| Historic Landslide in Rio during the 1980s http://pubs.usgs.gov/of/2001/ofr-01-0276/images/Fig26tn.jpg |
Massive landslides are usually triggered by certain movement. Earthquakes, faults moving or plates moving also. There is a South American plate or fault, but it does not get much activity on the Brazilian side. Mostly on the Pacific Ocean side, where Chile is. The landslides that occur in Rio de Janeiro, Brazil are because of the Serra do Mar, a coast range that goes all the way to the south eastern tip of Brazil. This is what features the famous sugar-loaves. the Serra do Mar gets triggered by intense summer rain storms. And because Rio is surrounded by hill slopes, water mixed in with the soil causes movements. The water bleeds through the soil causing the landscapes to move and landslides to occur. and these soil steep hill slopes are occupied a lot by the favelas in Rio. In Rio the most common slopes are colluvial mantle and is composed of 40% clay, in thick sand. This is a common trigger for movement in the soil, resulting in the landslides. Experiments and studies support and confirm that this occurs often in Rio and it is a major problem for the city, and people who live in the favelas.
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| A landslide in the favelas in Rio de Janeiro http://i.telegraph.co.uk/multimedia/archive/01553/landslide_1553760i.jpg |
Volcanic Activity in Rio?? True or Not??
There is a volcano in Rio, that is debated a lot. The Nova Iguacu "Volcano". Some support that it is an actual volcano some think it's not. Although it's characteristics are there. It has a cone shaped crater and appears to have forms form lava flow. Although it has never been proved. The features say it's a volcano but it has never been proved. The Nova Iguacu "Volcano" It's very famous to visit today, when you go to Rio.
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| The Nova Iguacu Volcano/Mountain in Rio de Janeiro, Brazil http://www.skyscrapercity.com/showthread.php?t=1493434 |
duff.ess.washington.edu/grg/publications/pdfs/fernandes_et_al.pdf
https:www.scribd.com/mobile/doc/141800150
Class Lectures: Volcanic Forms, Mass Wasting & Infiltration, Soils
