Transcript 2007_ReunionCollege - Department of Earth and Planetary

Civilization Exists Through Geologic Consent
2007 Washington University Reunion College
Michael Wysession, Professor of Geophysics
Department of Earth and Planetary Sciences
Washington University, St. Louis, Missouri
Lisbon earthquake, 1755.
Reunion College Quiz #1
May 17, 2007
Name____________________________________
1) Where was Atlantis?
2) Where was Eden?
3) Who killed off the Mayans?
4) What caused the Black Plague of the 1340s?
5) Why did so many Americans head West in 1816?
6) What caused the French Revolution?
7) What happens when we double the amount of CO2?
Earthquake Distribution
Volcano Distribution
Volcanoes and earthquakes largely at plate boundaries
Example: The
Complex
India/Asia Plate
Boundary
Northward
motion of India
deforms the
entire region
Example: The
Complex
India/Asia Plate
Boundary
Northward
motion of India
deforms the
entire region
This is the cause
of many
destructive
earthquakes
Pakistan
EQ, 2005
Sumatra EQ,
2004
Burma
Microplate Sumatra
Indian
Plate
The process of subduction that has created Indonesia
through volcanic activity, also makes it dangerous,
like with the deadly 2004 Sumatra quake.
Mt. St. Helens, Following the 1980 Eruption
Mt. Mazama erupted in 4860 BC:
 42x larger than Mt. St. Helens
Crater Lake, Oregon
Tsunami, Sumatra 2004 Earthquake
Courtesy of K. Sataki
Banda
Aceh:
Before….
Banda
Aceh:
Before….
and
After…..
Banda
Aceh:
Before….
and
After…..
What was the previous largest tsunami
in the Indian Ocean?
Giant Volcanic
Eruption of Krakatau
in 1883.
Giant Volcanic
Eruption of Krakatau
in 1883.
Can something like this change history?
The tsunami from the 1650 BCE
eruption of Mt. Thera may have
destroyed the cities there, giving
rise to the legend of Atlantis.
So….could this happen in America?!?
Massive
landslides in
places like the
Canary
Islands could
possibly
cause
enormous
Atlantic
tsunamis!
[Based on Ward
and Day, 2001]
There have also been
Giant Undersea
Landslides in the Puerto
Rico Trench!
An enormous
tsunami from the
Chixulub impact
likely hit North
America 65 million
years ago.
Chixulub
Crater
But the most significant affects on the history of
life and civilization come from changes in climate.
(δ18O  measure of ice on land  global temperature)
But the most significant affects on the history of
life and civilization come from changes in climate.
What drives the long-term temperature changes?
Mountains!!
 Erosion (Carbonic Acid)
 Deposition of Carbonates in the Oceans
 Reduced CO2 in Atmosphere
 Global Cooling
Appalachian Mtns
Himalayan Mtns
Allegheny Mtns
Ouachita Mtns
Taconic Mtns
What drives the intermediate-term temperature changes?
Fluctuations in Earth’s Orbit (Milankovich Cycles)
What about some of the narrow, sharp spikes?
~75,000 years ago
Toba Volcano – ~75,000 years ago
 280,000 km3 ejected!
 1 gigaton tnt explosion!
Volcanic eruptions can lower temperatures through
ejection into the atmosphere of
• Ash
• Aerosols like H2SO4 droplets
Based on genetic diversity, it is estimated that all
modern humans evolved from only 1000-10,000
individuals following the Toba eruption.
Warning!!!! Correlation does not necessarily imply
causation!!
This is a new field, and a lot of geological and
archaeological work remains to be done!
By 100,000 years ago,
Homo Sapiens was
emerging as dominant
hominid. Why?
?? Selection for large brains during strong Ice Ages
that occurred 120,000-90,000 years ago??
50,000-40,000 years ago
there was a cultural
explosion in Europe.
Why?
Warming trend in Europe.
Life was easier?
North American Mammoths evolved in Asia.
How did they get here 20,000 years ago?
20,000 years ago was time of Ice Ages.
Sea levels were low. Mammoths walked
here!
 Native Americans followed 14,000
years ago!!!!
The start of civilization
didn’t occur until 10,000
years ago. Why?
The start of a warm and relatively stable climate period!!!
Many cultures have a myth similar to the
story of the expulsion from Eden. Why?
Rising Sea Levels
After the End of the
Ice Age forced
many people from
their homelands!!
Ancient Persian
Gulf Shoreline
The Egyptian and Semitic peoples originated in
Eastern Europe. Why did they leave?
The Black Sea flooded dramatically 5,600 BCE!!
Most of these cultures have similar flood myths!!
3000 BCE: Time of alternating droughts and flooding.
 Complex societies like Akkadian Empire evolve in order
to survive.
Story of Joseph warning the Egyptian Pharoah to prepare
for 7 lean years.
2200 BCE: Period of extended drought causes Akkadian
Empire to collapse.
1900 BCE: Cold and dry period.
 Desertification destroys
Indus Civilizations.
1200 BCE: Variable
atmospheric circulation
patterns hurt agriculture.
 Also causes mass
migrations of Phrygian and
Hittite peoples.
Europe is warmed by
the Gulf Stream.
Who discovered the Gulf Stream?
Who discovered the Gulf Stream? Ben Franklin
It is believed that an a period of global warming could
freeze Europe.
The sudden flood of fresh water melted from
Greenland (not salty  less dense  doesn’t sink)
could shut off the Atlantic thermohaline circulation.
Alexander the
Great
500-400 BCE: North Atlantic
thermohaline circulation shuts
down.
 Colder temperatures in Europe
cause more southward migrations.
Macedonians overrun Greece.
300 BCE: Warming period in Asia.
 Opening of the “Silk Route.”
0 – 100 AD: Stable temperatures allow Roman Empire to
thrive. Empire = >60 million people. Rome = >1 million.
So…why did Rome collapse?
400-500 AD: Cold spell; prolonged freezing.
 Southward migration of Northern Europeans
Why was Leif Ericsson able to sail to America?
Why was Leif Ericsson able to sail to America?
950-1300 AD: Warm and dry period
950-1300 AD: Warm and dry period
 Mayan culture collapses
950-1300 AD: Warm and dry period
 American Southwest cultures like the one at Chaco
Canyon collapse. Anasazi peoples disappear.
Why does the
plague strike in
the 1300s?
1300 AD: Cold spell
due to a minimum in
solar activity
Great famine of
1315-1317
Black Death, 1345
Begins with flooding in China. More than 7 million
drown in Yangtze River.
Plague returned
in 1563, 1578,
1593, 1603,
1625, 1636, and
1665.
The 1563
outbreak in
places like
England was
worst than for the
Great Plague.
After 1815 there is a huge push of U.S.
Westward Expansion. Why?
1816 is known as the “Year without a summer.”
It snows in New England in the summer.
Volcanoes!
1812: Soufriere volcano, St. Vincent Island
1814: Mayon volcano, Philippines
1815: Tambora volcano, Indonesia
Why does the
French Revolution
occur in 1789?
1783: Hekla volcano, Iceland; Asama volcano, Japan
Examples of some other historic volcanic eruptions:
1150-1136 BCE: Hekla, Iceland
* Ashes rained in China for 10 days
* 90% of population of Scotland and North England died
209 BCE: Possibly Iceland
* Pan Ku (China): “great famine killed more than half the
population,” “people ate each other,” “the Emperor lifted
legal prohibitions against the sale of children”
* Stars were not seen at night in 208 BCE for 3 months
536 CE: Mt. Rabaul (New Guinea)
* Procopius (Byzantize historian): “The sun gave forth its light
without brightness, like the Moon,” “darkness lasted 18
months, and each day the sun shone for only 4 hours,”
* 80% of the population starved to death
Last 10,000 years: VERY warm AND stable!!
Future implications: Look at where the CO2 is headed.