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

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/cm 3 - Surface 2.8 g/cm 3

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

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

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

A 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.

HomogeneousHeterogeneous

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-Wave Shadow Zone

P-Wave Shadow Zone

P-Wave Shadow Zone

Seismic Discontinuities We hypothesize that the asthenosphere is partially molten because seismic waves slow down when they enter it.

Earth’s Layers

How do we know exactly where an earthquake occurs?

Benioff Zone Associated with Subduction

Cocos Plate Subducting Under the North American Plate

Current Seismic Activity