EARTHQUAKES

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EARTHQUAKES MODELIN THE SHAKIN Plate
tectonics part 3
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Your Conclusions??
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(No Transcript)
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Quake Wave Travel
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Fault in shales, Australia
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Junction fault, Appalachian Mountains
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Fault in France
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San Andreas Fault, California
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Fault types 1) normal
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2) Reverse/thrust
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3) Strike-slip
(left lateral)
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(right lateral)
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Types of seismic waves
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1) P wave
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2) S wave
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3) Surface wave (e.g., Love)
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isoseismals
Isoseismals for 1906 San Francisco, 1811-12 New
Madrid Quakes
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Seismic Risk Level in 50 years Blue small Red
large
Seismic Risk Level in 100 years Blue
negligible Green low Red high
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Quake measurement
seismograph seismometer
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• Richter scale
• based upon the largest waves generated by a
  quake
• Scale is logarithmic, i.e., based upon powers of
  10

(WAVE AMPLITUDE)
Richter 4 SHAKE
Richter 3 SHAKE
Richter 2 SHAKE


10X
100X
(ENERGY RELEASED)
Richter 4 SHAKE
Richter 3 SHAKE

31X
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Comparison between the Richter and Moment
Magnitude Scales
Moment magnitude scale considers the size of the
fault rupture, the amount of movement along the
fault, and the rocks stiffness or resistance
(estimated from the sizes of several types of
quake waves) measures the total energy released
by an earthquake generally considered the
preferred method of comparison for seismologists
Earthquake Richter Scale Moment Magnitude
New Madrid, MO, 1812 8.7 8.1
San Francisco, CA 1906 8.3 7.7
Prince William, AK 1964 8.4 9.2
Northridge, CA,1994 6.4 6.7
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Modified Mercalli Scale measures rating of
effects upon the earth surface, humans, objects,
and human-made structures ( as recorded by
observers) Roman numerals I-XII
.I. Not felt except by a very few under
especially favorable circumstances. II. Felt
only by a few persons at rest, especially on
upper floors of buildings. Delicately suspended
objects may swing. III. Felt quite noticeably
indoors, especially on upper floors of buildings,
but many people do not recognize it as an
earthquake. Standing motor cars may rock
slightly. Vibration like passing truck. Duration
estimated. IV. During the day felt indoors by
many, outdoors by few. At night some awakened.
Dishes, windows, and doors disturbed walls make
creaking sound. Sensation like heavy truck
striking building. Standing motorcars rock
noticeably. V. Felt by nearly everyone many
awakened. Some dishes, windows, etc., broken a
few instances of cracked plaster unstable
objects overturned. Disturbance of trees, poles,
and other tall objects sometimes noticed.
Pendulum clocks may stop. VI. Felt by all many
frightened and run outdoors. Some heavy furniture
moved a few instances of fallen plaster or
damaged chimneys. Damage slight.
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VII. Everybody runs outdoors. Damage negligible
in buildings of good design and construction
slight to moderate in well built ordinary
structures considerable in poorly built or badly
designed structures. Some chimneys broken.
Noticed by persons driving motor cars. VIII.
Damage slight in specially designed structures
considerable in ordinary substantial buildings,
with partial collapse great in poorly built
structures. Panel walls thrown out of frame
structures. Fall of chimneys, factory stacks,
columns, monuments, walls. Heavy furniture
overturned. Sand and mud ejected in small
amounts. Changes in well water. Persons driving
motor cars disturbed. IX. Damage considerable in
specially designed structures well-designed
frame structures thrown out of plumb great in
substantial buildings, with partial collapse.
Buildings shifted off foundations. Ground cracked
conspicuously. Underground pipes broken. X. Some
well-built wooden structures destroyed most
masonry and frame structures destroyed with
foundations ground badly cracked. Rails bent.
Landslides considerable from river banks and
steep slopes. Shifted sand and mud. Water
splashed over banks. XI. Few, if any (masonry),
structures remain standing. Bridges destroyed.
Broad fissures in ground. Underground pipelines
completely out of service. Earth slumps and land
slips in soft ground. Rails bent greatly. XII.
Damage total. Waves seen on ground surfaces.
Lines of sight and level distorted. Objects
thrown upward into the air.
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• Earthquake
• Hazards
• Structure failures
• Land, soil failures (e.g., land- and mudslides
• Soil liquefaction
• Fault scarps (vertical offsets)
• tsuamis