1.8 - Chile

Question 1

What effect does a high silica concentration in lava have on the properties of the lava and the ensuing eruption?

Answer 1

• Lava has a higher gas content
• Higher pressures within the magma chamber
• Violent eruptions

Question 2

What are the properties of andesitic lava?

Answer 2

• very viscous
• large silica concentration
• large gas content

Question 3

What sort of volcanoes are made by andesitic lava?

Answer 3

Composite volcanoes

Question 4

How do earthquakes occur at destructive plate boundaries?

Answer 4

• oceanic and continental plate move against each other
• tension builds up as plates catch on each other
• pressure is released when plates give way
• EQ occurs

Question 5

How does the depth of an earthquake affect its magnitude?

Answer 5

• shallower earthquakes have a larger magnitude
• as more energy reaches surface

Question 6

What are locked faults?

Answer 6

• faults which do not slip due to high friction between both plates at boundary
• accumulate large amounts of stress
• very high magnitude EQs

Question 7

What is the Benioff zone?

Answer 7

• An area of seismicity
• along the boundary where the subducting plate meets less dense plate

Question 8

What sort of plate boundary are the Andes on?

Answer 8

• Convergent/destructive

Question 9

What are the potential secondary effects of an earthquake in the Andes?

Answer 9

• landslides
• avalanches

Question 10

Which plates interact at the Andes?

Answer 10

Nazca and Antarctic plates subduct under South American plate

Question 11

What factors cause stresses on a rock face?

Answer 11

• angle of slope
• saturation of the face
• vibrations
• sea, cliff erosion at base
• earthquakes

Question 12

What factors add to the strength of a rock face?

Answer 12

• consolidation of material
• rock type
• porosity of soil
• tree/vegetation roots

Question 13

How does the formation of mountains create hazards?

Answer 13

• steepness of mountains can give rise to a large likelihood of landslides
• height of mountains causes moist air from sea to condense, thus rainfall
• folding of rock layers when mountains form creates faults and weaknesses within rock, landslides likely

Question 14

How does hydrology play into everything?

Answer 14

• rainfall caused by high mountain/volcano peaks pushing moist air higher
• condensation
• snow can accumulate to form glaciers, resulting steep valley sides
• increased stress on mountains