Which scenario led to the disaster that destroyed the city of ...

[futuristic]

Which scenario led to the disaster that destroyed the city of Armero in 1985?
 
  A) Heavy rains saturated the slopes of Nevado del Ruiz.
  B) Flooding eroded the slope of Nevado del Ruiz, oversteepening it.
  C) An earthquake shook the slope materials of Nevado del Ruiz loose, causing a landslide.
  D) Heat from the eruption of Nevado del Ruiz melted the volcano's ice cap.

Question 2

How does an Andean-type mountain-building event compare to a Cordilleran-type? Consider tectonic environments as well as processes of formation.
 
  What will be an ideal response?

[Jevvish]

Answer to Question 1

Answer: D

Answer to Question 2

Answer: Andean-type events occur when oceanic lithosphere subducts beneath continental lithosphere. Volcanic arcs develop through partial melting of the subducting plate, which can also result in the emplacement of batholiths. Forearc and back-arc basins develop on either side of the volcanic arc. Back-arc basins will result from extension of the crust as the deep-ocean trench rolls back.
Cordilleran-type events occur when buoyant crustal fragments collide with a continental margin during subduction. This buoyant materiala microcontinent, for examplewill accrete to the overriding plate as a accreted terrane. Fold-and-thrust belts are common.

[futuristic]

TY

[Jevvish]

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