Earthquakes and volcanoes

Question 1

Describe convection current

Answer 1

• The magma near the core is heated
• As the magma warms, it expands and become less dense - rises towards the crust
• Cools down when it nears the crust- denser and begins to sink
• Circular currents which are convection current- creates friction

Question 2

Define volcano

Answer 2

A vent (hole) in the earth’s surface where magma (lava), gas or ash escapes onto the earth’s surface or into the atmosphere.

Question 3

Define earthquake

Answer 3

A series of vibrations or movements in the earth’s crust.

Question 4

Define hot spot

Answer 4

Basically an intra-plate volcano caused by a weakness in the earth’s crust or particularly hot magma rising to the surface and breaking through the crust. Hawaii sits on and has been created by a hot spot.

Question 5

Lahars can be caused by….

Answer 5

• Melting snows
• Heavy rainfall/water content of magma
• Triggered by earthquakes

Question 6

Define lahars

Answer 6

Mud flows from explosive eruption. They are formed from ash mixed with water which can come from heavy rain and melted snow

Question 7

Why lahars are problematic?

Answer 7

• loss of life;
• destroy buildings/homes;
• inundate farmland/destroy crops/livestock;
• disrupt communications;
• bring down power lines/damage water pipes;