1. Earth’s Interior & Earthquakes

2. Part of the Earth Layers defined by composition Crust
Thin, rocky outer layer of Earth
Either oceanic crust or continental crust
Oceanic crust is 7 km thick

3. Mantle Core 82% of the Earth’s volume
Solid rock at the top, liquid at the bottom
Core
Composed of iron-nickel alloy
Extreme pressure found in the center of the core

4. Layers defined by Physical Properties
Lithosphere
The crust and uppermost mantle
Cool, rigid shell
100 km thick
Asthenosphere
Soft, comparatively weak layer
Below the lithosphere
Rock close to melting

5. Outer Core Inner Core Liquid layer 2260 km thick
Metallic iron generates Earth’s magnetic field
Inner Core
Solid layer having a radius of 1220 km
High temperatures and high pressure
Nickel mostly

6. Earthquakes

7. What is an earthquake?
Vibration of Earth produced by a sudden release of energy
Movements along the fault line.

8. Focus, Epicenter and Faults
Focus – point within the Earth where the Earthquake starts
Epicenter – location on the surface of Earth directly above the focus
Fault- associated with earthquake activity where movement has occurred

9. Elastic Rebound Hypothesis
Release of built-up energy
Most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great forces
When the strength of the rock is exceeded, it suddenly breaks, causing vibration of an earthquake

10. Foreshock vs. Aftershock
Foreshock – small quake that comes before a major earthquake
Aftershock – small quake that comes after a major earthquake

11. Seismology Seismology – study of earthquake waves
Seismograph – instruments that record earthquake waves
Seismograms – the record made by a seismograph

12. Earthquake waves Surface
Seismic waves that travel along Earth’s outer layer
Move up, down, and side to side
Most destructive earthquake waves
Last to arrive at the seismograph

13. Earthquake waves P waves S waves
They push (compress) and pull (expand) rocks in the direction the wave travels
Also known as compression waves
Can travel through solid, liquid, and gas
Fastest waves
S waves
Shakes particles at right angles to their direction of travel
Also known as transverse waves
Can only travel through solids
Slower than P waves but faster than surface waves

14. Exit Ticket C A B
Identify the waves recorded at A, B and C on the diagram