2.  An earthquake is ground movements that occur when blocks of rock in Earth move suddenly and release energy.  Earthquakes occur along fault lines. ◦ Faults are breaks in Earth’s crust where blocks of rock slide past each other.  As the plates move, pressure builds up near their edges, causing fault lines.

4.  The Focus is the place beneath Earth along a fault line where a block of rock breaks causing an earthquake.  The Epicenter is the exact spot on Earth’s surface directly above the focus.

6.  A wave is a disturbance in an substance that transports energy from one place to another.  Seismic waves are vibrations given off by Earthquakes that cause ground movements. ◦ When blocks of rock break, the released energy travels in seismic waves.

8.  Body waves (travel through Earth) ◦ P waves (primary waves) travel through solid, liquid, and gas because they move in a back and forth direction (slinky).  fastest ◦ S waves (secondary waves) can only travel through solids because they move up and down.  Second Fastest

11.  Surfaces Waves ◦ Only travel along Earth’s Surface. ◦ Travel back and forth and up and down. ◦ Slowest.

12.  A seismograph is a tool used to measure the size of an Earthquake based on seismic waves.  The Richter Scale measures the ground motion of Earthquakes. ◦ A scale of 1-10 where each magnitude increase is equal to 10 times the ground movement.

14.  The moment magnitude scale ◦ The modern rating system which measures the energy output of an earthquake.

15.  Mercalli Scale ◦ Measures earthquakes by the amount of damage they produce. (intensity)

16.  Stress is pressure on a block of rock causing it to bend and break (caused by Earth’s plates).

17.  Tension stress stretches rock, making it thinner. (occurs at Divergent Boundaries)

18.  Compression stress shortens and squeezes rock. (occurs at Convergent Boundaries)

19.  Shear stress pushes different blocks of rock past each other. (Occurs at Transform Boundaries)

20. ◦ Faults are breaks in Earth’s crust where blocks of rock slide past each other.

21.  Normal fault ◦ Caused by tension and can be found at divergent boundaries.

22.  Reverse Fault  Are a result of compression and can occur at convergent plate boundaries.

23.  Strike Slip Fault  Caused by shearing and can be found at transform boundaries.

24.  The Law of Superposition ◦ If rock layers are undisturbed, the youngest will be on top. Rocks will get older the deeper you get into the crust. ◦ Sediments are continuously deposited on top of each other. ◦ If rock layers are undisturbed, the deeper you get the older the rocks, fossils, etc. are.

27.  When rock layers are disturbed or changed, the oldest is not always found on the bottom. ◦ Folding, faulting, and the rise of magma change rock layers. ◦ Anytime igneous rocks cut across sedimentary rock layers, they are the youngest. ◦ This causes the law of superposition to be incorrect at times.

30.  The movement of Earth’s Plates and convection currents causes the rock cycle. ◦ Zones of subduction form magma, which rises and creates igneous rocks. ◦ Zones of subduction also create metamorphic rock, exposing rocks to extreme heat and pressure. ◦ When mountains are formed, they will weather, creating sediments and sedimentary rock.