Download 5.7 Notes What are Earthquakes? Objective: Explain what causes

5.7 Notes
What are Earthquakes?
Objective: Explain what causes Earthquakes and what happens during
one
Movements of the crust that you may or may not feel are called
tremors. Sudden, strong, shaking movements can cause a lot of
damage are called earthquakes.
The focus is the point beneath Earth’s surface where an earthquake
starts.
The epicenter is the place on Earth’s surface that is directly above the
focus. The surface of Earth shakes the hardest here.
Earthquakes are caused by faulting. Pressure increases along the faults,
causing the rocks to break at their weakest points. They slip and move
near the focus, releasing energy in the form of waves, or vibrations,
called seismic waves. Seismic waves travel out from the focus in all
directions.
Earthquakes are measured by seismographs. Seismographs are
instruments that detect and measure movements in the Earth’s crust,
and record it on a piece of paper called a seismogram. It has wavy
lines. The higher the lines, the stronger the earthquake