Transcript SwissRe - Department of Earth and Planetary Sciences

Earthquakes, Volcanoes, 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
PLATE
“Plate Tectonics,” The Basic Idea:
Locations of the Major Tectonic “Plates”
A Global Map of Earthquakes Also Shows the Plate Boundaries
Japanese Folklore:
Earthquakes caused by
giant Namazu.
Following the 1755 Lisbon earthquake on All Saint’s Day, the Spanish
Inquisition burned people at the stake to atone for the city’s sins.
The San Andreas Fault
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).
Earthquakes occur where earthquakes occur, and…
Earthquakes occur where seismometers exist
Earthquakes occur where earthquakes occur
Earthquakes occur where seismometers exist
Almost no
seismometers!!
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.
The Reelfoot Rift is a region of lower elevation
(which is why the Mississippi River flows
down through it!).
New Madrid earthquakes
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
Wabash Valley Seismic
Zone earthquakes:
The latest - Mw 5.2 on
April 18, 2008 (last
Friday!)
A DEVASTATING EVENT: THE SUMATRA
EARTHQUAKE OF DECEMBER 26, 2004
Burma
Microplate
Sumatra
Indian
Plate
Northward
Motion of
India
Deforms
the Entire
Region
Sumatra
Earthquake
Sumatra-Andaman Dec 26, 2004 EQ & Tsunami
Banda
Aceh:
Before….
Banda
Aceh:
Before….
and
After…..
So….could this happen in America?!?
Massive
landslides in
places like the
Canary
Islands could
cause
enormous
Atlantic
tsunamis!
There have also been
Giant Undersea
Landslides in the Puerto
Rico Trench!!!!
For Large Earthquakes,
Seismic Waves Circle
the Earth for Months to
Years, Making it Ring
Like a Gong.
(Earth’s Lowest Note,
With a Period of ~54
Minutes, is an E, Twenty
Octaves Below Middle E
on a Piano.)
Courtesy of J. Tromp
Courtesy of IRIS
Can Seismologists
Predict
Earthquakes?
(Only one earthquake
was ever successfully
predicted: 1975
Tangshan, China)
Earthquake Prediction: Animal Behavior?
Earthquake Forecasting: Seismic Gap Hypothesis?
Lack of success reminiscent of New York City “bear gap” hypothesis
USGS Forecast: Parkfield Earthquake in 1987
On Sep. 28, 2004,
the Parkfield EQ
finally happened!!
Was it is
successful
prediction???
Seismic Imaging Has Allowed Us to
Explore the Interior of Our Planet….
Courtesy of A.
Dziewonski
A Medical CT-Scan
DOWNWELLING
UPWELLING
Courtesy of S. Zhong
For a copy of this
presentation, please email
me at:
[email protected]
The information can also
be found (and more) in the
48-lecture Teaching
Company video course
“How the Earth Works”