Explain three ways in which a lahar can form. What will be an ...

[s.tung]

Explain three ways in which a lahar can form.
 
  What will be an ideal response?

Question 2

Compare and contrast the major types of calderas.
 
  What will be an ideal response?

[EAN94]

Answer to Question 1

Answer: Answers will vary but should say something about volcanic debris mixing with water. Some ways to form a lahar include rainfall, melting of glaciers, dam failure, and river water.

Answer to Question 2

Answer: Yellowstone-type calderas eject huge volumes of pyroclastic material mainly in the form of ash and pumice by way of pyroclastic flows. These types of calderas are very large and so poorly defined that it is difficult to identify them (they are often called supervolcanoes). Hawaiian-type calderas form gradually because of the loss of lava from a shallow magma chamber. Crater Lake-type calderas form when the magma chamber can no longer support the cone, and it collapses in on itself. This caldera eventually filled with water from rain and melting snow. The cone in Crater Lake is called Wizard Island.