Faults and Earthquakes

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# Faults and Earthquakes - PowerPoint PPT Presentation

Faults and Earthquakes ______________ – the shaking and trembling that results from the movement of rock beneath Earth’s surface ______________ – a force that acts on rock to change its shape or volume

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Faults and Earthquakes

• ______________ – the shaking and trembling that results from the movement of rock beneath Earth’s surface
• ______________ – a force that acts on rock to change its shape or volume
• ______________ - a change in the shape of rock caused by stress
• ______________ – squeezing stress
• ______________ – stress that pulls something apart
• ______________ – parallel forces acting in opposite direction
• ______________ - A break in the Earth’s crust where slabs of rock slip past each other

_______________

_______________

• Forms the upper half of the fault
• Block of rock that forms the lower half of a fault

Label A Hanging wall

Label B Footwall

Strike Slip Fault

What type of force causes this fault?___________

• Draw the arrows to show the directions they move.
Reverse (Thrust) Fault

What type of force causes this fault?___________

• Draw the arrows to show the directions they move.
Normal Fault

What type of force causes this fault?___________

• Draw the arrows to show the directions they move.
___________________
• A Mountain that forms where a normal fault up lifts a block of rock.
___________________
• Pushing together of part of the earth's crust from the ends, causing it to fold and ripple in the middle.
___________ and ___________
• Anticline – a fold in rock that bends upward
• Syncline – a fold in rock that bends downward in the middle to form a bow;
___________________
• Large area of flat land elevated high above sea level. Some form when vertical faults push up a large flat block of rock
Earthquakes
• ___________ – point beneath Earth’s surface where the rock is under stress breaks, triggering an earthquake
• ___________ – the point on the surface directly above the focus
• ___________ – vibrations that travel through Earth carrying the energy released during the earthquake

___________ - (P waves) arrive first; earthquake waves that compress and expand the ground like an accordion.

• ___________ - (S waves) come after the p waves; earthquake waves that vibrate from side to side and up and down. S waves cannot move through liquids.
• ___________ – when P and S waves reach the surface; they move more slowly but produce the most severe ground movements

Faults and Earthquakes

• Earthquake – the shaking and trembling that results from the movement of rock beneath Earth’s surface
• Stress – a force that acts on rock to change its shape or volume
• Strain - a change in the shape of rock caused by stress
• Compression – squeezing stress
• Tension – stress that pulls something apart
• Shear – parallel forces acting in opposite direction
• Fault - A break in the Earth’s crust where slabs of rock slip past each other

Shearing, tension and compression work over millions of years to change the shape and volume of rock

• Any change in the volume of Earth’s crust is called deformation. It causes the crust to bend, stretch, break, tilt, fold and slide.
Three Types of Faults

Strike-Slip

Thrust (Reverse)

Normal

Hanging Wall

Footwall

• Forms the upper half of the fault
• Block of rock that forms the lower half of a fault
Strike-Slip Fault
• Shearing creates strike slip faults. Rocks on either side of the fault slip past each other sideways with little up or down motion
Normal Faults
• Tension forces cause these faults. The fault is at an angle so that one block lies above the fault while the other lies below the fault.
Reverse (Thrust) Faults
• Compression forces. Has the same structure as a normal fault, but the blocks move in the opposite direction.
Mountain Building
• Over millions of years, fault movement can change a flat plain into a towering mountain range
• Form by Faulting
• Folding
• Anticlines and Synclines
• Plateaus
Fault-Block Mountains
• A Mountain that forms where a normal fault up lifts a block of rock.
Folding Mountains
• Pushing together of part of the earth's crust from the ends, causing it to fold and ripple in the middle.
Anticline and Syncline
• Anticline – a fold in rock that bends upward
• Syncline – a fold in rock that bends downward in the middle to form a bow;
Plateaus
• Large area of flat land elevated high above sea level. Some form when vertical faults push up a large flat block of rock
• What are the 3 main types of stress in rock?
• Describe the movements that occur along each of the three types of faults.
• How does Earth’s surface change as a result of movement along faults?
• If plate motion compresses part of the crust, what landforms will form there in millions of years?

How does energy of an earthquake travel through Earth?

• What are the different kinds of seismic waves?
• What are the scales used to measure the strength of an earthquake?
5sentences, main idea topic sentence
• Do you think that Japan's new warning system will keep people safer during earthquakes? Why or why not? What are some benefits and drawbacks of the new system?
Earthquakes
• Focus – point beneath Earth’s surface where the rock is under stress breaks, triggering an earthquake
• Epicenter – the point on the surface directly above the focus
• Seismic waves – vibrations that travel through Earth carrying the energy released during the earthquake

Seismic waves carry the energy of an earthquake away from the focus, through Earth’s Interior and across the surface.

• Energy is greatest at the epicenter
• But the most violent shaking can occur km away from the epicenter

Primary waves - (P waves) arrive first; earthquake waves that compress and expand the ground like an accordion.

• Secondary waves - (S waves) come after the p waves; earthquake waves that vibrate from side to side and up and down. S waves cannot move through liquids.
• Surface waves – when P and S waves reach the surface; they move more slowly but produce the most severe ground movements

Seismic Waves

• Through the Earth

When finished with the Achieve article and polls

• Copy the definitions of the following words into your notes
• Seismograph
• Magnitude
• Mercalli Scale
• Richter Scale
• Moment Magnitude Scale
• Complete the thought question on a separate piece of paper to turn in at the end of class
• Do you think that Japan's new warning system will keep people safer during earthquakes? Why or why not? What are some benefits and drawbacks of the new system?

Seismograph – records the ground movements caused by seismic waves as they move through the Earth

Measuring Earthquakes
• Magnitude – measurement of earthquake strength based on seismic waves and movements along the faults
• Mercalli Scale – rates earthquakes to their intensity and how it affects people, buildings and land surface
• Richter Scale - rating the size of seismic waves as measured by a seismograph. Accurate measurement for small nearby earthquakes
Moment Magnitude Scale
• Moment magnitude scale can be used to rate earthquakes of all sizes near or far. Estimate the total energy released by earthquakes

Earthquake tracking

On a separate piece of paper. Due at the end of classRAP your answers!!
• How does energy of an earthquake travel through Earth?
• What are the different kinds of seismic waves?
• What are the scales used to measure the strength of an earthquake?
• Describe how the energy released at an earthquake’s focus, deep inside Earth can cause damage on the surface many kilometers away from the epicenter.
Fold the paper

Step 1 Fold a sheet of paper

into a taco.

Step 2 Open the taco and fold it the opposite way making another taco and X-fold pattern on the sheet of paper.

Step 3 Use the outside tabs for labels and inside tabs for writing information.

Labeling

Definition & Picture

Volcano

Types of Eruptions

Quiet –

Violent -

Hot Spots

Definition & Picture

Definition & Picture

Shield Volcano

Composite Volcano

Extinct

Active

Dormant

Cinder Cone Volcano

Definition & Picture

Ring of Fire
• Area of earthquake and volcanic activity surrounding the Pacific Ocean
Volcanoes
• Weak spot in the crust where molten material called magma rises to the surface where it is renamed lava.
• The amount of silica in magma determines how easy the magma flows and if eruptions are quiet or violent
Types of Eruptions
• Quiet Eruptions - Magma with low amounts of silica and low viscosity erupts to form shield volcanoes.
• Violent Eruptions - Magma with high amounts of silica and high viscosity erupts explosively to form composite cones.
Shield Volcano
• Repeated lava flows during quiet eruptions build up a broad gently sloping volcanic mountain. Ex: Mauna Loa, Hawaii
Hawiian islands are formed this way
• Slow quiet lava flows build up the land (constructive) until the land is thicker than the water and forms an island
Hot Spots
• An area where magma melts through the crust like a blow torch; they lie in the middle of plate. Ex: Hawaiian Islands
Composite
• Layers of lava alternate with layers of ash, cinders and bombs in a composite; both quiet and explosive eruptions. Ex: Mt. Hood, Oregon
Composite volcanoes
• Examples of composite volcanoes include Italy's Vesuvius, Japan's Mount Fuji, and Washington State's Mount Rainier and Mount St. Helens

Mt. Rainier, Washington state

Mt. Fuji, Japan

Mt. Vesuvious 1943, infrared photo at night

Mt. St Helens, Washington state

Cinder cones
• When cinders erupt explosively from volcanic vents, they pile up around the vent forming a cone shaped hill. Ex: Sunset Crater, Arizona

Active – currently erupting or showing signs of unrest (ex: earthquake activity or gas emission)

• Dormant – not currently active, but could become restless or erupt
• Extinct – unlikely to erupt again
Mapping Earthquakes and Volcanoes

*You will be interpreting data on the locations of earthquakes and volcanoes to find patterns.

• Materials
• Map, list of locations, 2 colored pencils, piece of paper notebook paper
• Procedure

Mark the location of 12 earthquakes using one colored pencil and 12 volcanoes using another colored pencil

• Analyze and Conclude Questions (answered on the notebook paper)
• Observe the pattern of earthquakes and volcanoes over the surface of the Earth. Are they scattered at random or are they concentrated in certain areas? Describe your observations.
• Explain your observations – why do earthquakes and volcanoes occur in these areas?
• Use a reference map on page 204 of your textbook to label the names of 5 plateson your map.
• Observe the pattern of earthquakes and volcanoes in relation to crustal plates. Are they scattered all over the plates or is there a pattern? Describe your observations.
• Draw arrows on your map showing the direction of the plate movement (page 204).
• Is there a relationship between the direction of the movement and the pattern of earthquakes? Volcanoes? Describe and explain.