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Warm up
What is an earthquake?
What causes them?
Where do they occur?
earthquake
• Earth shakes
• A sudden release of energy due to a break
in the earth’s crust
Geometry
• Focus – break in the crust
• Fault – plane with movement
• Epicenter – point on the surface directly
above the focus
Crustal stress
• Compression – pushing together
• Tension – pulling apart
• Shear – pushing in different horizontal
directions
Folding & faulting
• Deformation change in the shape or
structure of the Earth’s crustal material
• include folding, faulting, breaking, bending,
sliding and tilting
• Results from extreme stress (motion of
plates)
• Elevated pressure and temperure effects
the behavior of stressed rocks
Ductile
• DUCTILE change shape without breaking
Folding – results from compression in ductile rocks
monocline
Syncline
Anticline
Evidence -rolling surfaces, basins, long hills,
ridges, valleys visible
Faulting
• BRITTLE - Crust fracture instead of folding
Types of Faults
Side view
• Shear – San Andreas,
Transform
• Tension – Divergent,
Sierra Nevadas
• Compression –
Convergent-,Himalayas
Body waves
• Body waves (P & S) go through the Earth Surface wave travel over the surface
• Primary – travel fastest, compression
waves, go through liquid and solid,
particles vibrate back & forth in the
direction the wave is traveling
• Secondary – travel slower, stopped by
liquid, transverse waves, particles vibrate
perpendicular to the direction of travel
Body waves
Surface waves
• Surface – craziest and slowest, do the
most damage, travel along the surface of
the earth
What we can learn
• Since P & S waves have different
characteristics they have been used to
determine the boundaries between the
layers of the earth
• Since P & S waves travel at different
speeds, scientists compare the arrival
times at 3 seismographs to determine the
location of the epicenter
Damage
• The most intense damage is at the
epicenter and where liquefaction occurs
• Liquefaction is most likely to occur in
natural or artificial landfill – Back Bay,
Boston, Marina District, San Francisco
Test format
• Chapters 9, 10 (II for more information on
the types of faults)
• Multiple choice
• Regular, 12 questions
• 8 volcanoes: 3 diagrams, 5 examples or
characteristics
• 10 short answer, (3 are identifying fault
type
• 4 open response, 11 to choose from