The official death toll to about 2,800 but the Miyagi police chief has said that more than 10,000 people are estimated to have died in his province alone.

The official death toll to about 2,800 but the Miyagi police chief has said that more than 10,000 people are estimated to have died in his province alone.

http://www.bbc.co.uk/news/world-asia-pacific-12729485

http://www.youtube.com/watch?v=TRDpTEjumdo

http://www.youtube.com/watch?v=AZ5WPXxNzPU

Earth’s Interiors

•Astronomy

•Drilling through the crust

•Earth’s delivery service -Kimberlite Pipes and Xenoliths

-Ophiolites

•Seismic data -Vibrational energy waves

- Earthquake data

How we know what’s inside

Astronomy

Calculating Earth’s Density

- Gravitational influence, mass

- Volume, Shape, Diameter

- calc. Density of Earth 5.5 g/cm3

- Surface 2.8 g/cm3

Drilling through the crust

Describing core. From left to right: Daniele Brunelli (Igneous Petrologist, Centre National de la Recherché Scientifique), Eric Hellebrand (Igneous Petrologist, Max-Planck-Institüt für Chemie), Hiro Tamura Hasebe (Igneous Petrologist, Kanazawa University), Heidi-Elisabeth Hansen (Igneous Petrologist, University of Bergen), Kevin Johnson (Igneous Petrologist, University of Hawaii), Satoko Ishimaru (Igneous Petrologist, Kanazawa University), Natsue Abe (Igneous Petrologist, Japan Marine Science and Technology Center), and Xixi Zhao (Paleomagnetist, University of California, Santa Cruz) in the background. [Photo ID: exp305_006]

Drilling through the crust

Kimberlite pipe

Xenolith

Earth’s delivery service

Kimberlite Mine in South Africa

Seismic Data

- Elastic rebound theory

What causes earthquakes

Instrument for measuring magnitude of earthquakes

Seismographs

Seismographs

Types of Siesmic Waves

Body Waves - travel thru the Earth - P waves

- S waves

Surface Waves - travel around the Earth - Love waves

- Rayleigh waves, ground roll

P Wave- result from alternating compression and expansion of material

P waves: - primary waves -

compressional wave

- movement is in the same direction that the wave is traveling

- highest velocity seismic wave (4mi/s)

- travel through solids, liquids, and gases

Earthquake Waves

S wave - distortion of material, perpendicular to the direction the wave is traveling.

S waves: - secondary waves -

transverse or shear waves - slower than P waves (2mi/s)

- can only pass through solids - slightly greater amplitude than P

waves

Earthquake Waves

Rayleigh

Love

Surface Waves

Surface Wave: - a seismic wave that travels along the surface of the Earth Surface Waves:

- dampen quickly, don't travel very far

Earthquake Amplitude

Equivalent tons of TNT

0 0.6

1 20

2 600 Smallest quake people can normally feel

3 20 000 Most people near epicenter feel the quake.

4 60 000 A small fission atomic bomb. Quakes above 4.5 can cause local damage

5 20 000 000 A standard fission bomb, similar to the first bomb tested in New Mexico, U.S.

6 60 000 000 A hydrogen bomb; can cause great damage locally.

7 20 billion Enough energy to heat New York City for 1 year

Large enough to be detected all over globe

8 60 billion Largest known: 8.9 in Japan and in Chile/Ecuador

San Francisco destroyed by 8.25 in 1906

9 20 trillion Roughly the world's energy usage in a year

Richter Scale

Modified Mercalli Intensity Scale from FEMA

I. People do not feel any Earth movement.

II. A few people might notice movement if they are at rest and/or on the upper floors of tall buildings.

III. Many people indoors feel movement. Hanging objects swing back and forth. People outdoors might not realize that an earthquake is occurring.

IV. Most people indoors feel movement. Hanging objects swing. Dishes, windows, and doors rattle. The earthquake feels like a heavy truck hitting the walls. A few people outdoors may feel movement. Parked cars rock.

V. Almost everyone feels movement. Sleeping people are awakened. Doors swing open or close. Dishes are broken. Pictures on the wall move. Small objects move or are turned over. Trees might shake. Liquids might spill out of open containers.

VI. Everyone feels movement. People have trouble walking. Objects fall from shelves. Pictures fall off walls. Furniture moves. Plaster in walls might crack. Trees and bushes shake. Damage is slight in poorly built buildings. No structural damage.

VII. People have difficulty standing. Drivers feel their cars shaking. Some furniture breaks. Loose bricks fall from buildings. Damage is slight to moderate in well-built buildings; considerable in poorly built buildings.

VIII. Drivers have trouble steering. Houses that are not bolted down might shift on their foundations. Tall structures such as towers and chimneys might twist and fall. Well-built buildings suffer slight damage. Poorly built structures suffer severe damage. Tree branches break. Hillsides might crack if the ground is wet. Water levels in wells might change.

IX. Well-built buildings suffer considerable damage. Houses that are not bolted down move off their foundations. Some underground pipes are broken. The ground cracks. Reservoirs suffer serious damage.

X. Most buildings and their foundations are destroyed. Some bridges are destroyed. Dams are seriously damaged. Large landslides occur. Water is thrown on the banks of canals, rivers, lakes. The ground cracks in large areas. Railroad tracks are bent slightly.

XI. Most buildings collapse. Some bridges are destroyed. Large cracks appear in the ground. Underground pipelines are destroyed. Railroad tracks are badly bent.

XII. Almost everything is destroyed. Objects are thrown into the air. The ground moves in waves or ripples. Large amounts of rock may move.

Liquefaction

LiquefactionA phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking.

Niigata, Japan 1964

Sand boil

Liquefaction induced road failure

1989 Loma Prieta

Tsunami

Travel of Seismic Waves

In homogeneous material, they travel in a straight line.

When seismic waves encounter a boundary, they will reflect or refract.

Homogeneous Heterogeneous

Reflection – return of wave off a boundary (bounce back)

Refraction – change in direction and velocity of the wave

Bedrock vs. Unconsolidated Sediments

Seismic Shadow

Zones

We hypothesize that the outer core is molten because S waves will not pass through it.

S-WaveShadow Zone

P-WaveShadow Zone

P-Wave Shadow Zone

Seismic Discontinuities

We hypothesize that the asthenosphere ispartially molten because seismic waves

slow down when they enter it.

Earth’s Layers

How do we know exactly where an earthquake occurs?

Benioff ZoneAssociated with Subduction

Cocos Plate

Subducting

Under the

North American

Plate

Current Seismic Activity

http://earthquake.usgs.gov/