Upload
others
View
4
Download
0
Embed Size (px)
Citation preview
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