What causes earthquakes?

Shaping Earth
Lesson 2: The Moving Crust
How does Earth’s crust move?
 The flowing of the upper mantle causes plates to move.
 Mountains may form by faulting or folding caused by pressure in Earth’s
crust. P 215
 Vocabulary:
 plates - large sections of Earth’s crust and upper mantle that move slowly
 fault – a crack in the earth’s surface formed when plates slide past each other
from side to side
 plateau – a high landform with a flat top
 fold – a bend in layers of rock formed when rock layers are slowly pushed
 mountain – a tall landform that rises to a peak
What causes earthquakes?
 The shaking of the ground during earthquakes can cause buildings to break
 Vocabulary:
 earthquake – a sudden shaking of the rock that makes up Earth’s crust
 tsunami – giant waved caused by a strong earthquake which causes the ocean
crust to lift suddenly
How do scientists study earthquakes?
 Seismic waves come from underground where the rock layers break apart.
 Vocabulary:
 seismic wave - vibration caused by an earthquake
 seismograph – an instrument that detects and records earthquakes; shows
seismic waves as jagged lines along a graph
What is a volcano?
 Lava is melted rock that has reached the Earth’s surface while magma is
melted rock below the Earth’s surface
 Most volcanoes are found near the edges of Earth’s plates, in the space
created when the two plates separate.
 When a volcano erupts again and again, layers of lava and ash build up
forming a mountain.
 Vocabulary:
 volcano – a mountain that builds up around an opening in Earth’s crust