Transcript Earthquakes - domenicoscience

EARTHQUAKES
Earthquake Facts
• An earthquake is the shaking and trembling
that results from sudden movement of the
earth’s crust.
• They occur along plate boundaries where
tension builds between rock layers.
• There are over 150,000 earthquakes every
year, however only about 75 of these are
significantly strong enough to be felt by
people.
Map of earthquakes in the past
three days (Jan, 2002)
Map of earthquakes in the past
week.
Map of earthquakes in the past
month, Dec15-Jan15, 2002.
Focus / Epicenter
• Focus - The point below the earth’s surface
where the rock breaks.
• Epicenter - point on the surface directly
above the focus.
• In general, a shallow focus earthquake
causes more damage than a deep focus
earthquake.
The Seismograph
P S
and Surface Waves
• P Waves arrive first and go through solid
and liquid. These are compression waves.
• S Waves arrive second and only go though
solid. They travel at right angles to the
shock wave.
• Surface waves arrive last and do most of
the damage. They are similar to waves on
the surface of a lake or ocean.
Earth’s Interior
• P & S waves act like a probe revealing the
earth’s interior.
• Remember that P-waves travel through both
liquid and solid while S-waves travel only
through solids.
If the earth had a solid core this
would represent the S/P waves.
The outer core is liquid
• Because earth has a liquid outer core there
is an S-wave shadow zone on the opposite
side of the world.
Distribution of Earthquakes
Tsunami
• An underwater disturbance such as an
earthquake or volcano can cause a Tsunami.
1946, a man stands before a wall of water
about to engulf him in Hilo, Hawaii
Tsunami damage in Hawaii from
the 1960 Chilean quake.
The Richter Scale
A photo gallery of famous quakes
Orange Trees Displaced along
the San Andreas Fault
North Ridge California, 1994
North Ridge California, 1994
Mexico City 1985 Liquefaction
Mexico City, 1985
Tangshan China 1976
San Francisco 1906
San Francisco
Chili 1960 Mag 9.5!
Alaska 1964
Peru 1970
San Francisco 1989
Kobe Japan, 1995
San Fernando California 1971
Some famous earthquakes
•
•
•
•
•
•
•
New Madrid Missouri 1811&1812
San Francisco 1906 (fire damage)
Alaska 1964 (Good Friday quake)
1970 Peru (deadliest in South America)
Tangshan China 1976 (deadliest this cent.)
Mexico City 1985 (liquefaction damage)
Chili 1960 (Most powerful Earthquake)
New Madrid Missouri 1811&12
• In 1811 & 1812 there were three major
earthquakes that rocked the central U.S.
• The New Madrid fault line is an old plate
boundary.
• The Mississippi River changed its course
after these powerful earthquakes.
San Francisco 1906
• This 8.3 magnitude earthquake ruptured
many gas lines and destroyed the city.
• 1500 people died many from the resulting
fires.
• The San Andreas fault line shifted 21 feet!
Peru 1970
• 66,000 people died making it the deadliest
earthquake in South America.
• The 7.8 magnitude quake had a high death
toll because many of the adobe houses
collapsed and there were massive landslides
in the Andes.
Alaska 1964
• This 8.7 magnitude earthquake was one of
the most powerful in modern times.
• The quake lasted four minutes however the
death toll was only 130.
Tangshan China, 1976
• At 3:40 in the morning on July 28th 1976 a
7.8 magnitude quake obliterated the city of
Tangshan China.
• Approximately 500,000 people died making
it the deadliest quake in the twentieth
century.
Strange Phenomena in Tangshan
• Well water rose & fell three times the day
before the quake occurred.
• Chickens refused to eat and mice were seen
running around looking for hiding places.
• The night before, people saw strange lights
and loud sounds in the sky. (A similar
phenomena occurred in Mexico city, 1985.)
Mexico City 1985
• Over 9,000 people died from an 8.1
magnitude earthquake.
• Liquefaction - caused much of the damage.
• Liquefaction is when once stable soil turns
into a fluid and cannot support buildings.
End of part I: Earthquakes
Continue for part II: Volcanoes
Volcanoes
Presentation Outline
•
•
•
•
•
•
1. Cinder Cone Volcanoes
2. Shield Volcanoes
3. Stratovolcano or composite cone
4. Flood Basalts
5. Volcanic features
6. Volcano vocabulary
Basic Facts on Volcanoes
• There are over 600 active volcanoes. 2/3 of
these are found along the ring of fire
tectonic plate boundary.
• There are three basic types of volcanoes:
• 1. Shield Volcanoes.
• 2. Stratovolcano or composite cone.
• 3. Cinder Cone Volcanoes.
Location of earthquakes &
volcanoes
The three types of Volcanoes
Cinder Cone Volcanoes
• These are generally small volcanoes that
build up from ejected lava and rock
fragments.
Sunset Carter in Arizona is a
typical cinder cone volcano
Sunset crater
Paracutin: Cinder Cone
• In 1943 a cinder cone volcano grew in a
farmer’s corn field west of Mexico City.
• In one day the cone grew grew over 130
feet.
Paracutin 1943, Mexico
Paracutin
Paracutin
Church near Paracutin
Capulin Cinder Cone Volcano,
New Mexico
Capulin New Mexico
Shield Volcanoes
• Shield Volcanoes have a very broad base
and gentle slope.
• The Hawaiian Islands are classic shield
volcanoes.
• Shield Volcanoes generally have gentle
liquid lava eruptions.
• Mauna Loa is the largest volcano on Earth!
Shield volcanoes
The Hawaiian Shield Volcanoes
Mauna Loa, from its base to
summit is 30,000 feet!
Two types of Lava
• Pahoehoe is smooth rope like lava
• AA lava is rough and angular
• Both types of lava are associated with shield
volcanoes.
Pahoehoe & AA Lava
Stratovolcano or composite cone
• The stratovolcano or composite cone
represents your “typical” volcano.
• These Volcanoes are cones made of
alternating layers of lava and pyroclastic
rock layers.
The Stratovolcano
Stratovolcano
Indonesia, Where 67% of all
volcanic related deaths occur.
Tambora Indonesia
The Tambora Eruption 1815
• This was the most powerful eruption in
recorded history and had the highest death
toll.
• Over 92,000 died from this eruption mostly
from starvation. 1815 was known around
the world as “the year without a summer.”
• Ash from Tambora block sunlight causing
massive starvation around the world.
Krakatoa Indonesia
before & after 1883
Krakatoa 1883
• When Krakatoa erupted it blew away 2/3 of
the uninhabited island.
• The Tsunami that resulted killed over
36,000 people on the nearby island of Java.
• The explosion was so powerful it was heard
3,000 miles away in Australia!
Krakatoa today
Krakatoa
Mt. Vesuvius & Pompii Italy
• For over 16 years earthquakes shook the
Roman city of Pompii Italy.
• In 79 AD Mt. Vesuvius finally exploded
causing hot ash and sulfur gases to bury the
city of Pompii.
• Over 20,000 Romans were fossilized from
the explosion of Mt. Vesuvius.
Mt Vesuvius & Italy
A fossilized dog from Pompii
A Roman Soldier
A recent 1944 eruption of
Mt. Vesuvius
Mt. Pelee & the city of Martinque
• In 1902 Mt. Pelee erupted destroying the
Caribbean city Martinque.
• 29,000 people died. The only survivor was
a prisoner in an underground jail.
• Nuee ardent is a hot ash flow and caused
most of the destruction.
Mt. Pelee today
Mt. Pelee in 1902
Mt. Pelee
The destruction of Martinque
The Cascade Mountain Range
• The Cascade Mountain range is located in
the North West United States and contains
some of the most famous volcanoes.
• These include: Mt. St. Helens, Crater lake,
Mt. Ranier, Mt. Baker, Mt. Hood, Mt.
Shasta, Mt. Hood, to name a few.
Crater Lake Oregon
• About 6,000 years ago Mt. Mazama in
Oregon blew its top creating a large caldera.
• This caldera filled in with water creating the
6 mile wide Crater Lake National Park.
How Crater Lake formed
Crater Lake Oregon
Crater Lake & Wizard Island
Crater Lake & Wizard Island
Mt. St. Helens 1980
• On May 18, the dormant volcano Mt. St.
Helens in Washington state erupted.
• The top 1,300 feet of the mountain
disappeared in a few minutes.
Mt. St. Helens, May 1980
The ash fall-out from Mt. St.
Helens
Diagram of the eruption
Mt. St. Helens after 1980
Mt. St. Helens today
Volcanic flood basalts
• Liquid lava comes up from cracks or
fissures in the earth’s crust. This lava can
cover many square miles of earth.
• The dark mare on the moon are flood
basalts.
Deccan India
• Deccan India is the worlds largest flood
basalt.
• The region in west central India is called the
Deccan traps.
• The Deccan traps are composed of black
basalt 6,500 feet thick.
Deccan India
Deccan traps, India
The Columbia River flood
Basalts
• A large region of the U.S. extending from
Yellowstone Wyoming to the Columbia
River in Washington is composed of flood
basalt.
Flood Basalts in North West U.S.
Arial view of flood basalts
Columbia River Flood Basalt
Columbia River flood basalt
El Malpais National Monument
• A flood basalt igneous rock region extends
from New Mexico to Arizona and includes
the El Malpais (bad land) national
monument.
El Malpais New Mexico
Arial view of flood basalt in
New Mexico
El Malpais New Mexico
Lava tube in El Malpais
Volcanic Necks
• When erosion removes the softer rock
around a volcano the more resistant
volcanic neck is exposed.
• Ship rock New Mexico and Devil’s Tower
are two examples of an exposed volcanic
neck.
The volcanic neck
Erosion exposes the neck
Devil’s Tower Wyoming
Devil’s Tower
Formation of a Volcanic Neck
Ship Rock New Mexico
Ship Rock New Mexico
Volcanic Vocabulary
• Nuee ardente is a fiery cloud of hot gas.
• Lahar mudslides that result from a volcanic
eruption.
Nuee Ardente
Lahar
Three levels of volcanic activity
• 1. Extinct - has not erupted in recorded
history.
• 2. Dormant - has erupted in recorded history
but is currently “sleeping.”
• 3. Active - means it is currently erupting.
The End