Time To See Your Advisor Evidence of Plate Tectonics Plate Map...

1

Evidence of Plate Tectonics Earthquakes

• Time To See Your AdvisorPlate Map

Animation link • http://www-personal.umich.edu/~vdpluijm/plates.gif

http://www.ucmp.berkeley.edu/geology/tectonics.html

Dynamo that creates

magnetic field

• http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html

Movement of Magnetic

North

• http://www.nasa.gov/vision/earth/lookingatearth/29dec_magneticfield.html

Movement of Magnetic pole since 1600s

• http://www.geolab.nrcan.gc.ca/geomag/long_mvt_nmp2_e.shtml

Apparent Polar

wandering for North America

and Eurasia

Pole location

with moving continents

2

Magnetic Reversals in volcanic stratigraphy

Magnetic Reversal

Age Scale

Lava Magnetized in Normal Field

Lava Magnetized in reversed fieldLater Lava Magnetized in Normal

FieldSea floor spreading

documented by magnetic reversals

Magne-tometerSurvey

Magnetic Anomalies

Age of Sea Floor

• http://earth.geol.ksu.edu/sgao/g100/plots/0829_04_age_of_ocean_floor.jpg

3

Earthquake Locations Japan Trench earthquakes JOIDES Resolution

Age of Emperor Seamount Chain Velocities of Plates Radio Telescope

Plate movement over 200 my Wegener’s Pangaea 200 mya (early Jurassic)

4

150 mya (late Jurassic) 100 million years ago 90 mya (Cretaceous)

50 mya (early Cenozoic) 20 mya (late Cenozoic) Present Day

In 50 million years? In 250 million years?? Lithospheric Plates

5

Earthquake Locations

• http://earth.geol.ksu.edu/sgao/g100/plots/0916_global_seismicity.jpg

Pressure Wave

• Push-pull motion• Parallel to direction of wave energy

movement (propagation)• Go through all types of materials

– Sound waves are pressure waves– Primary seismic waves are pressure waves

Primary Wave

http://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.html

Shear Wave

• Transverse--Side to side motion• Can only go through solid materials• Secondary seismic waves• Slower than primary waves

Secondary Wave

http://astro.uchicago.edu/cara/outreach/se/ysi/1999/intro2.html

Earthquake: seismic waves

World Series Earthquake apartment building Seattle, WA

• Feb 28, 2001, Nisqually quake rocked the Central Puget Sound region

• 6.2 Richter Magnitude • 6.8 Moment magnitude• Centered 57.5 km south-southwest of

Seattle and 52.4 km deep

http://128.205.131.100:591/archives/Seattle.html

http://www.scec.org/earthquakes/

1906 San Francisco fire

6

Focus, epicenter, fault Orange grove offset, So Cal Before deformation

Strain Release of strain After strain released

Summary of elastic rebound

San Andreas Fault System Seismograph

7

Seismogram showing seismic waves P-waves P-waves

S-waves S-waves S-type surface waves

Ocean-type surface waves Summary of seismic waves Seismic wave travel time curves

8

Difference of P and S wave travel time

Mercalli scale

Richter magnitude determined by seismic wave recording on a

seismogram

Earthquake magnitudes and expected worldwide occurrence