Civilization Exists Through Geologic Consent

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Civilization Exists Through Geologic
Consent NESTA 2007 Michael Wysession, Professor
of Geophysics Department of Earth and Planetary
Sciences Washington University, St. Louis,
Missouri
Lisbon earthquake, 1755.
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Earthquake Distribution
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Volcano Distribution
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Volcanoes and earthquakes largely at plate
boundaries
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Example The Complex India/Asia Plate
Boundary Northward motion of India deforms the
entire region
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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
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Burma Microplate
Indian Plate
Sumatra
The process of subduction that has created
Indonesia through volcanic activity, also makes
it dangerous, like with the deadly 2004 Sumatra
quake.
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Mt. St. Helens, Following the 1980 Eruption
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Mt. Mazama erupted in 4860 BC ? 42x larger
than Mt. St. Helens
Crater Lake, Oregon
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Tsunami, Sumatra 2004 Earthquake
Courtesy of K. Sataki
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Banda Aceh Before.
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Banda Aceh Before. and After..
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Banda Aceh Before. and After..
What was the previous largest tsunami in the
Indian Ocean?
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Giant Volcanic Eruption of Krakatau in 1883.
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Giant Volcanic Eruption of Krakatau in 1883.
Can something like this change history?
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The tsunami from the 1650 BCE eruption of Mt.
Thera may have destroyed the cities there, giving
rise to the legend of Atlantis.
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So.could this happen in America?!?
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Massive landslides in places like the Canary
Islands could possibly cause enormous Atlantic
tsunamis!
Based on Ward and Day, 2001
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There have also been Giant Undersea Landslides in
the Puerto Rico Trench!
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An enormous tsunami from the Chixulub impact
likely hit North America 65 million years ago.
Chixulub Crater
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But the most significant affects on the history
of life and civilization come from changes in
climate.
(d18O ? measure of ice on land ? global
temperature)
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But the most significant affects on the history
of life and civilization come from changes in
climate.
What drives the long-term temperature changes?
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Mountains!! ? Erosion (Carbonic Acid) ?
Deposition of Carbonates in the Oceans ?
Reduced CO2 in Atmosphere ? Global Cooling
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Allegheny Mtns Ouachita Mtns
Himalayan Mtns
Taconic Mtns
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What drives the intermediate-term temperature
changes?
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Fluctuations in Earths Orbit (Milankovich Cycles)
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What about some of the narrow, sharp spikes?
75,000 years ago
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Toba Volcano 75,000 years ago ? 280,000 km3
ejected! ? 1 gigaton tnt explosion!
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• Volcanic eruptions can lower temperatures through
  ejection into the atmosphere of
• Ash
• Aerosols like H2SO4 droplets

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Based on genetic diversity, it is estimated that
all modern humans evolved from only 1000-10,000
individuals following the Toba eruption.
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Warning!!!! Correlation does not necessarily
imply causation!! This is a new field, and a lot
of geological and archaeological work remains to
be done!
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By 100,000 years ago, Homo Sapiens was emerging
as dominant hominid. Why?
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?? Selection for large brains during strong Ice
Ages that occurred 120,000-90,000 years ago??
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50,000-40,000 years ago there was a cultural
explosion in Europe. Why? Warming trend in
Europe. Life was easier?
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North American Mammoths evolved in Asia. How did
they get here 20,000 years ago?
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• 20,000 years ago was time of Ice Ages. Sea levels
  were low. Mammoths walked here!
• Native Americans followed 14,000 years ago!!!!

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The start of civilization didnt occur until
10,000 years ago. Why?
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The start of a warm and relatively stable climate
period!!!
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Many cultures have a myth similar to the story of
the expulsion from Eden. Why?
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Rising Sea Levels After the End of the Ice Age
forced many people from their homelands!!
Ancient Persian Gulf Shoreline
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The Egyptian and Semitic peoples originated in
Eastern Europe. Why did they leave?
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The Black Sea flooded dramatically 5,600 BCE!!
Most of these cultures have similar flood myths!!
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3000 BCE Time of alternating droughts and
flooding. ? Complex societies like Akkadian
Empire evolve in order to survive.
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Story of Joseph warning the Egyptian Pharoah to
prepare for 7 lean years.
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2200 BCE Period of extended drought causes
Akkadian Empire to collapse.
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1900 BCE Cold and dry period. ? Desertification
destroys Indus Civilizations.
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1200 BCE Variable atmospheric circulation
patterns hurt agriculture. ? Also causes mass
migrations of Phrygian and Hittite peoples.
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Europe is warmed by the Gulf Stream.
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It is believed that an a period of global warming
could freeze Europe.
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The sudden flood of fresh water melted from
Greenland (not salty ? less dense ? doesnt sink)
could shut off the Atlantic thermohaline
circulation.
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Alexander the Great
500-400 BCE North Atlantic thermohaline
circulation shuts down. ? Colder temperatures in
Europe cause more southward migrations.
Macedonians overrun Greece.
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300 BCE Warming period in Asia. ? Opening of
the Silk Route.
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0 100 AD Stable temperatures allow Roman
Empire to thrive. Empire gt60 million people.
Rome gt1 million.
Sowhy did Rome collapse?
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400-500 AD Cold spell prolonged freezing. ?
Southward migration of Northern Europeans
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Why was Leif Ericsson able to sail to America?
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Why was Leif Ericsson able to sail to
America? 950-1300 AD Warm and dry period
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950-1300 AD Warm and dry period ? Mayan culture
collapses
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950-1300 AD Warm and dry period ? American
Southwest cultures like the one at Chaco Canyon
collapse. Anasazi peoples disappear.
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Why does the plague strike in the 1300s?
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• 1300 AD Cold spell due to a minimum in solar
  activity
• Great famine of 1315-1317
• Black Death, 1345

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Begins with flooding in China. More than 7
million drown in Yangtze River.
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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.
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After 1815 there is a huge push of U.S. Westward
Expansion. Why?
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1816 is known as the Year without a summer. It
snows in New England in the summer.
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Volcanoes!
1812 Soufriere volcano, St. Vincent Island 1814
Mayon volcano, Philippines 1815 Tambora volcano,
Indonesia
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Why does the French Revolution occur in 1789?
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1783 Hekla volcano, Iceland Asama volcano, Japan
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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
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Last 10,000 years VERY warm AND stable!!
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Future implications Look at where the CO2 is
headed.