Earth and SpaceLesson 7.8 – Earthquakes

I can describe earthquakes and seismic waves. (4b)1. Earthquakes are the result of a sudden release of energy in the Earth's lithosphere that creates seismic waves.

a. The waves travel through the Earth and over its surface.b. There are two main types of waves: primary (P) and shear (S). P waves are longitudinal and move the fastest while S waves are transverse and slower.

I can describe earthquakes and seismic waves. (4b)2. Earthquakes occur at faults. Faults are cracks in the Earth’s lithosphere.

a. As the plates move past each other, they sometimes get stuck. Pressure builds up until the pieces slip, releasing the energy that built up as seismic waves.b. Faults often occur near transform boundaries or places where two tectonic plates are sliding past each other.

I can describe earthquakes and seismic waves. (4b)3. The strength of an earthquake was previously reported with the Richter scale. Today, the magnitude of an earthquake is reported. It is measured with a seismometer.

a. A magnitude 3.0 or lower earthquake is mostly unnoticeable and a magnitude 7.0 causes serious damage over large areas.

I can describe earthquakes and seismic waves. (4b)b. The magnitude of an earthquake measures the amplitude of the seismic waves. It is a logarithmic scale which means each whole number increase is an increase in amplitude by a factor of 10.c. A magnitude 4.0 has seismic waves with an amplitude 10 times larger than a 3.0. A magnitude 5.0 has waves with an amplitude 100 times larger than 3.0.

101001,00010,000100,0001,000,000

I can describe earthquakes and seismic waves. (4b)4. As seismic waves move through the Earth, they change direction because of the different types of rock they move through.

a. Different rock types change the speed the waves travel causing them to bend.

I can describe earthquakes and seismic waves. (4b)b. S waves do not travel through the core but may be converted to compressional waves (K) when they enter the core

c. If a wave hits the surface and is reflected it is shown with an extra letter (PP, PPP, SS).

Guided Practice

Guided Practice

  #1 #2 #3 #4 #5 #6

Magnitude of Earthquake 9.0 6.0 7.0 8.5 8.0 7.0

Times Stronger

10X1000

X

Compared To

8.0 4.0 5.0 3.0

Guided Practice7. A longitudinal wave is moving through the Earth, this is a wave. If it bends and reflects off of the surface twice, this would be shown on a map of Earth’s interior using a .8. A certain wave is moving through the Earth’s interior but turns into a compression (K) wave when it hits the outer core. This was a wave which moves than a P wave.

primary

PP

shear slower

I-N-D-E-P-E-N-D-E-N-TDo you know what that

means?

Exit Ticket(5 questions)

1.As tectonic plates slip past each other, energy is released. What is formed by this release of energy? A. Richter ScalesB. SeismographsC. Subduction zonesD. Seismic waves

2. Which statement below describes where earthquakes occur?

A. Earthquakes occur at subduction zones usually near transform boundaries.

B. Earthquakes occur at subduction zones usually near convergent boundaries.

C. Earthquakes occur at faults usually near transform boundaries.

D. Earthquakes occur at faults usually near convergent boundaries.

3. An Earthquake has a magnitude of 5.0. Which of these describes the likely result of this earthquake?

A. It will not be felt and there will be no damage.

B. It will be felt, but there will be no damage.

C. There will be some amount of damage with some structures falling.

D. There will be widespread damage with entire cities destroyed.

4. An earthquake has a magnitude of 5.0. What would the magnitude be of an earthquake 1,000 times stronger?

5. A scientist is studying the seismic waves produced by an earthquake and representing them on a map of the Earth’s interior. The wave she is studying arrives very quickly after being reflected three times by the Earth’s surface. How would this wave be shown on the map of the Earth’s interior?

A. PPB. PPPC. SD. SSE. K