Lesson - 2.1 Internal Structure of the Earth.pptx

lecture

1. Internal Structure of the Earth

2. Types of Seismic Waves BODY WAVES come from the focus and emanate in all directions through the interior of the Earth. Divided into two subtypes: P – waves (push-pull) S – waves (up – down) SURFACE WAVES - the up and down and side to side waves that travel across the surface; the slowest. Love waves Rayleigh waves

3. 2 KINDS OF BODY WAVES PRIMARY OR P-WAVE - compresses and expands the material through which it moves; a longitudinal wave; the fastest wave that can travel through all types of materials (solid, liquid and gas). SECONDARY OR S-WAVE - vibrates the particles of its medium up-and-down and side-to-side; a transverse wave; slower than P-wave that travels only in solid material.

4. 2 KINDS OF SURFACE WAVES LOVE WAVES - named after the discoverer Augustus Love; horizontal surface waves, moving from side to side; can cause bridges and buildings to collapse. RAYLEIGH WAVES - named after Lord Rayleigh; similar to rolling water waves, producing up and down, and sideways movement of the ground that makes it to be more destructive.

5. Seismic waves have other significant characteristics. First, seismic waves travel most rapidly in rigid materials. Second, seismic waves travel faster in deeper areas. This is because deeper areas experience much higher pressure, causing the rocks there to become more compact. Third, the path of seismic waves is bent or refracted as they travel across two unlike materials. This occurs between the boundary between two unlike materials, called discontinuity .

6. The Earth is made up of Three (3) main layers: Crust Mantle Core

7. Crust * Earth's solid exterior which is composed of a great variety of rock types that respond in diverse ways and at varying rates to surface processes. *The crust makes up 1% of the Earth. * The crust of the Earth is broken into many pieces called plates.

8. Crust Oceanic Crust crust beneath the oceans consist mainly of dense rock (basalt - dark in color) thickness ranges from 3 km Continental Crust crust that forms the continents consist mainly of less dense rock (granite - lighter in color) approximately 70 km thick

9. Mantle The mantle is the layer below the crust. The mantle is the largest layer of the Earth. Composed of solid rock matter. Less dense than the core.

10. Between the crust and the mantle is the boundary known as the Mohorovicic discontinuity. Simply called the “Moho”, the boundary was discovered by Andrija Mohorovicic in 1909 using seismic readings from an earthquake near his town.

11. Core An iron rich sphere at the center part of the Earth. Consists of two distinct sections, the inner core and the outer core.

12. Outer Core The outer core is liquid because it blocks the passage of seismic S-waves. It is the fluid (magma like) part of the Core.

13. Inner Core *Has temperatures and pressures so great that the metals are squeezed together and are not able to move. * The inner core is a solid.

14. EPICENTER Location on Earth’s surface that lies directly above the focus of an earthquake.