Earthquakes, Tsunamis, and a Modern Journey to the Center of the Earth

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Earthquakes, Tsunamis, and a Modern Journey to
the Center of the Earth Michael
Wysession Professor of Geophysics, Dept of Earth
and Planetary Sciences Washington University, St.
Louis, Missouri
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PLATE
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Plate Tectonics, The Basic Idea
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Locations of the Major Tectonic Plates
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A Global Map of Earthquakes Also Shows the Plate
Boundaries
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Japanese Folklore Earthquakes caused by giant
Namazu.
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Following the 1755 Lisbon earthquake on All
Saints Day, the Spanish Inquisition burned
people at the stake to atone for the citys sins.
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by Nathanial Crouch, 1734
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The San Andreas Fault
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More reasonable assessment, based upon actual
seismicity
The Global Seismic Hazard Assessment Program
(GSHAP), with the support of the International
Council of Scientific Unions (ICSU), and endorsed
as a demonstration program in the framework of
the United Nations International Decade for
Natural Disaster Reduction (UN/IDNDR).
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Earthquakes occur where earthquakes
occur Earthquakes occur where seismometers exist
Almost no seismometers!!
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The NMFZ is associated with the Reelfoot Rift a
failed rift zone that was active 750 million
years ago, as the supercontinent Rodinia began to
break up.
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The Reelfoot Rift is a region of lower elevation
(which is why the Mississippi River flows down
through it!).


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New Madrid earthquakes
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Notice all the earthquakes EAST of the NMSZ!
The NMSZ might be finished (for now?). It might
be time for a different failed rift to undergo
some continental creaking.
o Historical o Instrumental
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Wabash Valley Seismic Zone earthquakes The
latest - Mw 5.2 on April 18, 2008 (last Friday!)
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A DEVASTATING EVENT THE SUMATRA EARTHQUAKE OF
DECEMBER 26, 2004
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Indian Plate
Burma Microplate
Sumatra
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Northward Motion of India Deforms the Entire
Region
Sumatra Earthquake
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Sumatra-Andaman Dec 26, 2004 EQ Tsunami
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Banda Aceh Before.
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Banda Aceh Before. and After..
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So.could this happen along the East Coast?!?
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Massive landslides in places like the Canary
Islands could cause enormous Atlantic tsunamis!
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There have also been Giant Undersea Landslides in
the Puerto Rico Trench!!!!
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Seismologists read seismograms to learn about
the earth.
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For Large Earthquakes, Seismic Waves Circle the
Earth for Months to Years, Making it Ring Like a
Gong.
Courtesy of J. Tromp
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Drum head vibrations
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For Large Earthquakes, Seismic Waves Circle the
Earth for Months to Years, Making it Ring Like a
Gong. (Earths Lowest Note, With a Period of 54
Minutes, is an E, Twenty Octaves Below Middle E
on a Piano.)
Courtesy of J. Tromp
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Courtesy of IRIS
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Can Seismologists Predict Earthquakes? (Only
one earthquake was ever successfully predicted
1975 Tangshan, China)
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Earthquake Prediction Animal Behavior?
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Earthquake Forecasting Seismic Gap Hypothesis?
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USGS Forecast Parkfield Earthquake in 1987
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On Sep. 28, 2004, the Parkfield EQ finally
happened!! Was it is successful prediction???
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Seismic Imaging Has Allowed Us to Explore the
Interior of Our Planet.
Courtesy of A. Dziewonski
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This is what parts of the U.S. used to look
like..
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Seismic Imaging Reveals the Most Likely Places to
Find Oil and Natural Gas.
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It also will also reveal the locations of the
next big source of energy, methane gas hydrates.
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DOWNWELLING UPWELLING
Courtesy of S. Zhong
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Earths Mantle Convection is driven by internal
radioactive decay. ? Like a bowl of Miso Soup in
a microwave oven (and the continents
are the pieces of tofu!)!
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A Medical CT-Scan
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The Japan Subduction Zone
Courtesy of D. Zhao
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Results from seismic tomography
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Many different possible interpretations of
the seismic tomographic images
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Water Might be Continually Pumped Into the Lower
Mantle Via Sinking Ocean Seafloor
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EarthScope
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Fantasy Writers Idea of the Core-Mantle
Boundary.
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Artists Idea of the Core-Mantle Boundary.
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Lowermost Mantle Graveyard of Ancient Ocean
Seafloor
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Lowermost Mantle Birthplace of Hotspot Mantle
Plumes
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Magnetic Field Lines in Earths Iron Core
Courtesy of G. Glatzmaier
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Magnetic Field Lines in Earths Iron Core The
Field FLIPS RANDOMLY Every Few 100,000 Years (or
so)!
Courtesy of G. Glatzmaier
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Magnetic Field Lines in Earths Iron Core The
Field FLIPS RANDOMLY Every Few 100,000 Years (or
so)!
Courtesy of G. Glatzmaier
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Magnetic Field Lines in Earths Iron Core The
Field FLIPS RANDOMLY Every Few 100,000 Years (or
so)!
Courtesy of G. Glatzmaier
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Magnetic Field Lines in Earths Iron Core The
Field Strength has recently decreased by 10. Are
we beginning a new field reversal??
Courtesy of G. Glatzmaier
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For a copy of this presentation, please email me
at michael_at_seismo.wustl.edu
The information can also be found (and more) in
the 48-lecture Teaching Company video course How
the Earth Works