Civilization Exists Through Geologic Consent2007 Washington University Reunion College

Michael Wysession, Professor of GeophysicsDepartment of Earth and Planetary SciencesWashington 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

Sumatra EQ, 2004

Pakistan EQ, 2005

Example: The Complex

India/Asia Plate Boundary

Northward motion of India

deforms the entire region

This is the cause of many

destructive earthquakes

The process of subduction that has created Indonesia through volcanic activity, also makes it dangerous, like with the deadly 2004 Sumatra quake.

Burma Microplate Sumatra

Indian Plate

Mt. St. Helens, Following the 1980 Eruption

Crater Lake, Oregon

Mt. Mazama erupted in 4860 BC: 42x larger than Mt. St. Helens

Courtesy of K. Sataki

Tsunami, Sumatra 2004 Earthquake

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)

What drives the long-term temperature changes?

But the most significant affects on the history of life and civilization come from changes in climate.

Mountains!! Erosion (Carbonic Acid)

Deposition of Carbonates in the Oceans Reduced CO2 in Atmosphere

Global Cooling

Taconic Mtns

Allegheny MtnsOuachita Mtns

Himalayan MtnsAppalachian 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 ago280,000 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 AkkadianEmpire 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.

500-400 BCE: North Atlantic thermohaline circulation shuts down.

Colder temperatures in Europe cause more southward migrations.Macedonians overrun Greece.

Alexander the Great

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 periodMayan culture collapses

950-1300 AD: Warm and dry periodAmerican 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.

1812: Soufriere volcano, St. Vincent Island

1814: Mayon volcano, Philippines

1815: Tambora volcano, Indonesia

Volcanoes!

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.