10.3

Question 1

Volcanoes

Answer 1

-Magma accumulates below weak spots in the earths crust
-During a volcanic eruption, magma is pushed to the surface.
-Once magma reaches the surface, it is called lava. Lava can reach ~1200oC!
-Lava cools and solidifies to form new rock.

Question 2

weak spots in the plate boundary

Answer 2

-Plate boundaries are where the Earth’s crust is the thinnest / weakest.
-Divergent plate boundaries create weaknesses in the crust as separating plates thin the crust, allowing magma to find its way up.
-Convergent boundaries also create weak spots – as the subducting plate melts, magma rises to form volcanoes

Question 3

Hotspots

Answer 3

Hot spots are isolated weak points in the crust that are away from a plate boundary.
Scientists are still not sure why hot spots exist.
The hot spot creates a volcano / volcanic island directly above it.
As the tectonic plate moves across the hot spot, new volcanoes form, leaving a chain of islands behind it.

Question 4

earthquakes

Answer 4

Tectonic plates are typically held together with friction.
When other forces overcome the friction forces, the plates slip – releasing waves of energy into the rock or water around it
Earthquakes most commonly occur at plate boundaries – especially convergent boundaries

Question 5

primary waves waves

Answer 5

travel longitudinally back and forth motion, travel fast

Question 6

secondary waves

Answer 6

move transversally up and down, moves slower than p waves

Question 7

surface waves

Answer 7

move in a rolling motion, they are the slowest and they cause the most damage

Question 8

earthquake focus and epicenter

Answer 8

Earthquakes happen at specific points where the earth slips – usually along fault line.
The location where the quake starts is called the focus (this may be hundreds of kilometers underground!)
The location directly above the focus at ground level is called the epicenter.