Section 2 Notes
Earthquakes and Seismic Waves
Earthquakes
•Forces of plate movement cause earthquakes
•Most earthquakes begin in the lithosphere within about 100 kilometers of Earth’s surface
•The earthquake starts at the focus
•Directly above the focus is the epicenter
Seismic Waves
•Seismic waves carry energy from an earthquake away from the focus, though Earth’s interior and across the surface
•Earthquakes send out 2 types of Seismic waves P waves (Primary) and S waves ( Secondary)
Earth’s Interior:
Focus – energy is released ( the beginning)
P wave – rocks will move back and forth in the same direction as the wave, they can travel through liquid and solid; they destroy buildings ( They are the fastest traveling waves)
S wave – rocks move in angles or side to side and up and down in the direction of the waves; they can only travel through solid; they shake the ground back and forth
Earth’s Surface
•Epicenter – right above the focus ( When locating the epicenter you need 3 locations)
•Surface Waves – earth generates wave that travel outward from the epicenter. These waves cause most of the destruction through ground movement ( They are the slowest traveling waves)
Measuring Earthquakes
•Mercalli Scale – this measures how much damage the earthquake caused. It is measured in roman numerals. (see page 55 for the scale)
•Richter Scale – this measures how strong the earthquake was in magnitudes
•Seismograph – measures and records seismic waves
•Moment Magnitude Scale – measures total energy released by an earthquake
Earthquakes and Seismic Waves
Earthquakes
•Forces of plate movement cause earthquakes
•Most earthquakes begin in the lithosphere within about 100 kilometers of Earth’s surface
•The earthquake starts at the focus
•Directly above the focus is the epicenter
Seismic Waves
•Seismic waves carry energy from an earthquake away from the focus, though Earth’s interior and across the surface
•Earthquakes send out 2 types of Seismic waves P waves (Primary) and S waves ( Secondary)
Earth’s Interior:
Focus – energy is released ( the beginning)
P wave – rocks will move back and forth in the same direction as the wave, they can travel through liquid and solid; they destroy buildings ( They are the fastest traveling waves)
S wave – rocks move in angles or side to side and up and down in the direction of the waves; they can only travel through solid; they shake the ground back and forth
Earth’s Surface
•Epicenter – right above the focus ( When locating the epicenter you need 3 locations)
•Surface Waves – earth generates wave that travel outward from the epicenter. These waves cause most of the destruction through ground movement ( They are the slowest traveling waves)
Measuring Earthquakes
•Mercalli Scale – this measures how much damage the earthquake caused. It is measured in roman numerals. (see page 55 for the scale)
•Richter Scale – this measures how strong the earthquake was in magnitudes
•Seismograph – measures and records seismic waves
•Moment Magnitude Scale – measures total energy released by an earthquake