Earthquakes and Volcanoes

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Earthquakes and Volcanoes
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EARTHQUAKESPlate Tectonics

• Lithosphere the crust and upper part of the
  earths mantle

1. Inner Core
2. Outer Core
3. Mantle
4. Crust

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EARTHQUAKESPlate Tectonics

• Plates large pieces of the lithosphere
• Theory of plate tectonics the idea that the
  earths crust is made of moving plates
• Plate Boundaries places where the plates meet
• Scientists think as the magma in the Earths
  mantle moves, it causes the plate boundaries to
  collide, separate or slide along each other.

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EARTHQUAKESPlate Tectonics

• Scientists believe the Earth is made up of large
  plates that float on the partly melted rock of
  the Earths mantle.
• Pangaea a large landmass that some scientists
  think may have existed at one time
• No recorded observations

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EARTHQUAKESCauses of Earthquakes

• Earthquakes often occur when rocks along the
  plate boundaries shift suddenly and release
  stored energy.
• Construction of large buildings and the movement
  of molten rock under a volcano can also cause
  earthquakes.

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EARTHQUAKESCauses of Earthquakes

• Faults breaks in the earths surface along
  which rocks can move
• Three kinds of faults determined by how the
  rocks move against each other (thrust or reverse
  fault, normal fault, strike-slip fault)
• Reverse fault rocks push together until a
  section of rock moves upward

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EARTHQUAKESCauses of Earthquakes

• Three kinds of faults determined by how the
  rocks move against each other (thrust or reverse
  fault, normal fault, strike-slip fault)
• Normal fault rocks moving apart
• Strike-slip fault rocks moving horizontally
  past each other

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EARTHQUAKESEarthquake Waves

• Earthquakes occur below the surface of the earth.
• Focus (A) beginning point of an earthquake
• Seismic waves vibrations that flow out from the
  beginning point of an earthquake
• Epicenter (B) the point on the surface of the
  earth directly above the focus

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EARTHQUAKESEarthquake Waves

• Body waves seismic waves that occur beneath the
  surface of the earth
• P Waves primary waves fastest moving travel
  in a straight path by a push and pull motion
  these waves move back and forth

S Waves secondary waves move more slowly move
in an up and down zigzag pattern causes the
particles in the rock to vibrate to the direction
in which the wave is moving
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EARTHQUAKESEarthquake Waves

• Surface Waves the slowest moving and most
  destructive waves
• Can move back and forth in a zig zag pattern
  fastest moving land waves
• Can move in a circular pattern rolling motion
  along the ground

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EARTHQUAKESDetecting Earthquakes

• Seismograph a machine that detects, times, and
  measures the movement of the earth
• Seismograms records of the movements of the
  earth
• Seismologists scientists who study the movement
  of the earth

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EARTHQUAKESMeasuring Earthquakes

• Mercalli scale based on the amount of
  destruction caused to man-made structures
• Measures observable destruction
• Richter scale measures the magnitude of an
  earthquakes seismic waves and assigns it a
  number
• Magnitude strength of the seismic waves of an
  earthquake, this is how much energy is released.

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EARTHQUAKESBuilding for Earthquakes

• Features that help structures withstand
  earthquakes
• Concrete reinforced with steel rods
• Foundation laid in rock
• Steel framing

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EARTHQUAKESRelated Disasters

• Tsunami giant ocean waves triggered by
  earthquakes, volcanoes, or landslides
• Other catastrophic events associated with
  earthquakes
• Volcanic eruptions
• Landslides

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VOLCANOES

• Magma molten rock under the earth
• Volcano are a form of a mountain, they occur
  when a crack in the earths surface allows magma
  and gases to come to the surface
• Volcanologists scientists who study volcanoes
• Magma chambers pockets of molten rock in the
  earths lithosphere
• Lava hot molten rock that breaks through the
  surface of the earth
• Vent opening in the surface of the earth
  through which lava flows
• Crater the bowl shape at the top of a main vent

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VOLCANOESCauses of Volcanoes

• Volcanic ash jagged bits of crushed rock
• Volcanic cone funnel-shaped mound

• Draw this Diagram in your notes.
• Side Vent
• Vent
• Lava
• Magma Chamber

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VOLCANOESLocations of Volcanoes

• Volcanic activity may occur under the ocean, at
  hot spots, along plate boundaries, and along the
  Ring of Fire.
• Ring of Fire active volcanoes around the edges
  of the Pacific Ocean
• Under water eruptions (submarine eruptions) are
  20x more frequent than eruptions on land
• Hot spots places where a pool of very hot magma
  rises toward the surface and forms new land

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VOLCANOES ClassifyingBy Shape

• Shield volcano large, gradually sloping sides
  erupts continuous flowing lava mild, continuous
  eruptions
• Cinder cone resembles a hill has a bowl-like
  crater usually has more than one vent made of
  cinders
• Cinders bits of ash and lava
• Composite cone steep sides and layers of lava
  and tephra
• Tephra a mixture of cinders, ash, and rock
  emitted by a volcano

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VOLCANOES ClassifyingBy How Often They Erupt

• Volcanoes can have more than one kind of eruption
  because one eruption can change the conditions
  inside a volcano, causing it to erupt differently
  the next time.
• Active volcano one that has erupted at some
  point during a recorded time period and is
  expected to erupt again
• Dormant volcano has erupted in the distant past
  but is currently inactive and not expected to
  erupt again
• Extinct volcano does not have a recorded
  eruption and is not expected to erupt in the
  future
• There is NO guarantee that it will remain extinct

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VOLCANOES ClassifyingBy The Type of Eruption

• Hawaiian eruption runny lava and little or no
  cinder, ash or steam quiet may continue for
  long periods of time
• Strombolian eruption fountain of lava that runs
  down the sides
• Vulcanian eruption violent causes a loud
  explosion that sends lava, ash, cinders, and gas
  into the air
• Pelean eruption produces a pyroclastic flow
  (avalanche of red-hot dust and gases emitted by a
  volcano)
• Plinian eruption most powerful spews lava,
  blows gases, ash, and debris into the atmosphere
• Pyroclastic flow a high-speed flow of very hot
  gases and dust

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VOLCANOESEffects of Volcanoes

• Vog volcanic gases volcanic fog pollutes the
  air and can cause acid rain and respiratory
  problems
• The gases, ash, and dust of volcanoes can cause
  cooling in the weather.
• Dangers of Volcanoes
• Debris flow when part of the mountain collapses
  and mud and rock fragments surge down the
  mountain
• Products of Volcanoes
• Soil rich in nutrients, valuable gems
• Igneous rock formed as magma and lava cool and
  harden

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VOLCANOESEffects of Volcanoes

• Other thermal eruptions
• Hot spring a heated pool of warmed ground water
• Geyser a hot spring that blows steam and water
  into the air
• Mud pots a hot spring that contains more mud
  than water

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Review for CFA 11 Earthquakes Volcanoes

• Earthquakes occur along breaks in the earth
  surface, these breaks are called___________. List
  and Describe the 3 types.
• The _________is the beginning part of an
  earthquake the ____________is the point on the
  surface of the earth directly above the focus.
• ________ ________ are the vibrations that flow
  out of the beginning point of an earthquake. List
  and Describe the 3 types.
• What are the 2 scales used to measure the
  strength of an earthquake? How do they differ?
• What is magnitude?
• What is a volcano?
• Where can volcanic activity occur?
• What is the ring of fire?
• What are some of the effects of a volcanic
  eruption?
• What types of geological events occur at plate
  boundaries?