Earth’s InteriorEarth’s Interior

Inferred propertiesInferred properties

A. The Inner CoreA. The Inner Core Believe it is solid iron and Believe it is solid iron and

nickelnickel• . earth is so dense, it . earth is so dense, it

means the interior must be means the interior must be made of a material much made of a material much more dense than the crust.more dense than the crust.

• Meteorites from space Meteorites from space have far more iron and have far more iron and nickel in them than does nickel in them than does earth’s crust.earth’s crust.

• Earth has a magnetic field. Earth has a magnetic field.

B. Earth has layersB. Earth has layers 1. Earthquake waves tell us earth 1. Earthquake waves tell us earth

changes with depth. There are changes with depth. There are internal layers.internal layers.• Lithosphere is lightest and solidLithosphere is lightest and solid• Mantle is mostly solid and the source Mantle is mostly solid and the source

of mineralsof minerals• Outer core is mostly iron and nickel Outer core is mostly iron and nickel

and is liquidand is liquid• Inner core is solid and iron and nickelInner core is solid and iron and nickel

How did it happen?How did it happen?

Early ‘proto-earth’Early ‘proto-earth’ Loose accumulation of material rotates Loose accumulation of material rotates

and tightensand tightens Continuously ‘smashed’ by meteors, space Continuously ‘smashed’ by meteors, space

debris, comets: debris, comets: accretionaccretion Internal heat flow allowed liquid, dense Internal heat flow allowed liquid, dense

metals (iron and nickel) to sink to the metals (iron and nickel) to sink to the centercenter

Silicates actually ‘fell’ as rock from sky, Silicates actually ‘fell’ as rock from sky, creating crustcreating crust

A ‘planet’ hit early earth, superheating it A ‘planet’ hit early earth, superheating it and creating the moon.and creating the moon.

Use page 10 EsrtUse page 10 Esrt For aspects For aspects of interior of interior earth, look earth, look at page 10 at page 10 ESRT.ESRT.

How do we How do we know? We know? We don’t…..we don’t…..we infer from infer from earthquake earthquake behaviors.behaviors.

Quake behavior near the surface.

Earthquakes http://www.vcsd.k12.ny.us/5712_125217113812/lib/5712_125217113812/

Quakes_and_Chile.doc

http://www.iris.edu/hq/programs/education_and_outreach/animations#E

1. 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 Quakeshttp://rev.seis.sc.edu/earthquakes.html

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

animations Animation of a quake: http://www.iris.edu/hq/files/programs/education_and_outreach/aotm/

15/B&R5_Earthquake.mov and many other animations and videos:

http://www.iris.edu/hq/programs/education_and_outreach/animations#E

The shaking: Link to animation of each wave in earth: http://www.iris.edu/hq/files/programs/education_and_outreach/aotm/6/

SeismicBuilding-Narrated480.mov and simple animations:

http://www.iris.edu/hq/files/programs/education_and_outreach/aotm/6/SeismicWaveAnimations-Braile%20copy.ppt#283,1,Slide 1 A complete PowerPoint presentation that uses Seismic wave animations

For little animations, etc of quake information: http://www.geology.sdsu.edu/visualgeology/geology101/geo100/earthquakes2.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. Terminologya.The focus is the location of the actual quake.. http://earthquake.usgs.gov/

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

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

12. Locating Earthquakeshttp://neic.usgs.gov/neis/eq_depot/2002/eq_021103/ak_seismic_waves.html 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.

5000 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….

http://www.ehs.washington.edu/fsoemerprep/earthquake.shtm 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: http://rev.seis.sc.edu/es/earthquakes/2010/02/27/06/34/14/stations/GT/PLCA?help=on to check on Chile

Argentina seismogram

New Mexico seismogram

http://www.oiles.co.jp/en/menshin/building/isolate/ for quake houses http://www.eram.k12.ny.us/education/components/docmgr/default.php?sectiondetailid=1750

0&catfilter=446#showDoc

link to current quake maps.

p-wave arrival at 21:58:30

s-wave arrival at 22:02:45

surfacewaves

Sesimogram from Binghamton, NY for Haiti quake