Tectonics: 1.9 - Chile Con Carnage

Question 1

Destructive plate boundary

Answer 1

Plates move towards each other and collide (converging)

Question 2

Benioff Zone

Answer 2

Area where a slab/plate moves down into, making it an area of seismicity (area where EQs are frequent)

Question 3

Benioff zone effect on EQs

Answer 3

The deeper the focus, i.e deeper the Benioff zone, the stronger the EQ

(High friction in Benioff zone -> more pressure -> stronger EQ)

Question 4

Benioff zone effect on Volcanoes

Answer 4

Oceanic crust melts, as well as some water and impurities seeping in (hydration melting)

Melted crust rises and penetrates cracks in continental crust, forming sticky andesitic lava due to impurities

Sticky lava gets stuck in vent, pressure builds up and results in an explosive eruption. Lava is viscous so it doesn’t travel far before cooling, forming a composite volcano

Question 5

Benioff zone effect on Tsunamis

Answer 5

Generally stronger and more frequent than at constructive boundaries, because constructive boundaries don’t have Benioff zones -> focus of EQ is shallower -> EQ is weaker -> less water displaced -> weaker tsunami

Question 6

Secondary hazard: liquefaction

Answer 6

When Land containing water is shaken, chasing the water to rise to the surface

Question 7

Other secondary hazards

Answer 7

Landslide, flooding (from ruptured mains pipe), contamination of stagnant water