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Earthquakes and Volcanoes


... rocks moving horizontally past each other EARTHQUAKES Earthquake Waves ... a high-speed flow of very hot gases and dust VOLCANOES Effects of ... – PowerPoint PPT presentation

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Title: Earthquakes and Volcanoes

Earthquakes and Volcanoes
EARTHQUAKESPlate Tectonics
  • Lithosphere the crust and upper part of the
    earths mantle
  1. Inner Core
  2. Outer Core
  3. Mantle
  4. Crust

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.

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

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

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

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

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

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
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

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

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
  • Magnitude strength of the seismic waves of an
    earthquake, this is how much energy is released.

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

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

  • 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

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

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

VOLCANOES ClassifyingBy Shape
  • Shield volcano large, gradually sloping sides
    erupts continuous flowing lava mild, continuous
  • Cinder cone resembles a hill has a bowl-like
    crater usually has more than one vent made of
  • 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

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
  • There is NO guarantee that it will remain extinct

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
  • 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

VOLCANOESEffects of Volcanoes
  • Vog volcanic gases volcanic fog pollutes the
    air and can cause acid rain and respiratory
  • 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
  • Products of Volcanoes
  • Soil rich in nutrients, valuable gems
  • Igneous rock formed as magma and lava cool and

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

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
  • What types of geological events occur at plate
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