Earth’s Interior Inferred properties

A. The Inner Core  Believe it is solid iron and nickel. earth is so dense, it means the interior must be made of a material much more dense than the crust.. earth is so dense, it means the interior must be made of a material much more dense than the crust. Meteorites from space have far more iron and nickel in them than does earth’s crust.Meteorites from space have far more iron and nickel in them than does earth’s crust. Earth has a magnetic field.Earth has a magnetic field.

B. Earth has layers  1. Earthquake waves tell us earth changes with depth. There are internal layers. Lithosphere is lightest and solidLithosphere is lightest and solid Mantle is mostly solid and the source of mineralsMantle is mostly solid and the source of minerals Outer core is mostly iron and nickel and is liquidOuter core is mostly iron and nickel and is liquid Inner core is solid and iron and nickelInner core is solid and iron and nickel

How did it happen?

Early ‘proto-earth’  Loose accumulation of material rotates and tightens  Continuously ‘smashed’ by meteors, space debris, comets: accretion  Internal heat flow allowed liquid, dense metals (iron and nickel) to sink to the center  Silicates actually ‘fell’ as rock from sky, creating crust  A ‘planet’ hit early earth, superheating it and creating the moon.

Use page 10 Esrt  For aspects of interior earth, look at page 10 ESRT.  How do we know? We don’t…..we infer from earthquake behaviors.

Quake behavior near the surface.

Earthquakes Seismic waves: sudden release of energy that builds up along faults and boundaries in the lithosphere. 2. energy travels in waves and moves outward in all directions

3. waves can be refracted, reflected, absorbed and transmitted at interfaces

4. There are different types of quake waves. The energy is released at once, but not all the waves travel at the same speed

5. ‘P’ waves a. ‘P’ or primary waves are the fastest (like lightning is faster than thunder) b. these are compressional and can pass through anything.

6. ‘S’waves are shear or secondary a. about half the speed of ‘P’ waves b. cannot travel through LIQUIDS (can’t go through outer core) c. are transverse:

7. ‘L’ or love/surface waves a. combination of various motions b. roll the ground c. only at surface d. cause most damage

8. Measuring Quakes a. Seismic stations: location with a seismograph that picks up quake waves:

animations Animation of a quake: B&R5_Earthquake.mov B&R5_Earthquake.mov and many other animations and videos: The shaking: Link to animation of each wave in earth: eismicBuilding-Narrated480.mov eismicBuilding-Narrated480.mov and simple animations: eismicWaveAnimations-Braile%20copy.ppt#283,1,Slide 1 A complete PowerPoint presentation that uses Seismic wave animationscomplete PowerPoint presentation For little animations, etc of quake information: uakes2.htm uakes2.htm

9. Measuring magnitude a. Magnitude is the STRENGTH of the waves: it indicates the energy released when the crust MOVED during the quake. B. Uses modified Richter scale of 1-10, but it’s logarithmic

10. Terminology a. The focus is the location of the actual quake b.Epicenter is the point on the surface above the focus c.Fault is a break along which the crust moves

d. Quake depth: how far below the surface depends on the boundary type: Volcanoes of the World.kmz Volcanoes of the World.kmz

11. The intensity of a quake: how much did it affect people and their property? Measured using the Mercalli Scale

12. Locating Earthquakes a. The seismograms from 3 different seismic stations are used to find the epicenter of an earthquake. b. The P and S wave arrival times for EACH seismic station are used to determine how far that station is from the epicenter.

c. S – P Travel time Find difference between arrival of s and p waves. Find a place on the graph where the S and P lines are that far apart. Read down to x-axis. That’s the distance from station to quake. 6.5 “ 5000 km P arrived 6.5 minutes before S

d. Draw a circle around the station So far, you only know how far you are, but not what direction…. Use a compass to draw a circle of the correct radius on a map. The quake is somewhere on that circle km

e. To find the EPICENTER You must make two more circles to triangulate:

13. Liquifaction Loose soil exacerbates (intensifies) the shaking. Hard, cold bedrock diminishes the shaking. liquifaction.ppt

14. Planning for Earthquakes Mercalli Scale: classifies earthquakes according to INTENSITY: how they impact humans and their property. Scale of I-XIV How badly an area is affected by the earthquake depends on: Distance from quake Magnitude of quake Building construction Population density Type of material the waves travel through….

for earthquake suggestions i. earthquake belts: most in danger because on active boundaries. ii. Areas on fault zones, such as the Mississippi River Valley (New Madrid Fault) can be at great risk iii. Most preparation involves good building techniques. iv. Safety measures during and after an earthquake NewMadridEQ.ppt

Chilean quake February 27, 2010: to check on Chile Argentina seismogram New Mexico seismogram

for quake houses 0&catfilter=446#showDoc link to current quake maps. 0&catfilter=446#showDoc Sesimogram from Binghamton, NY for Haiti quake