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Earthquakes

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Title: Earthquakes


1
Lecture 19 Earthquakes
2
Lecture Outline
I Definitions II Properties A) Focus and
Epicenter B) Seismic Waves i. Body
Waves ii. Surface Waves C) Strength i. I
ntensity ii. Magnitude III Effects IV Plate
Tectonics and Earthquakes A) Plate
Boundaries i. Divergent ii. Convergent
iii. Transform B) Subduction Angle V Conclusions
Lecture 19 i
3
Definitions
earthquake - the vibration felt when energy is
released
abruptly by the sudden displacement of rock
along faults within the Earth's crust
fault - fracture or fracture zone
along which there has
been displacement of the sides relative to
one another
fault line - the intersection of a fault with
the surface of the
Earth, or the trace of a fault on a surface of
reference
4
Tectonic Deformation Elastic Rebound
5
Tectonic Deformation Elastic Rebound
6
Properties
  • Focus
  • Epicenter
  • Seismic Waves
  • Stength

7
Seismic Waves
  • Body Waves
  • P (primary) Waves
  • S (secondary) Waves
  • Surface Waves
  • Love Waves
  • Rayleigh Waves

8
Seismic WavesBody Waves
P (Primary)Waves
S (Secondary)Waves
9
Seismic WavesBody Waves - Refraction
10
Seismic WavesBody Waves - Pathways
11
Seismic WavesSurface Waves
Rayleigh Waves
Love Waves
12
Detecting Seismic Waves
13
Detecting Seismic Waves
14
Detecting Seismic Waves
15
Detecting Seismic Waves
16
Detecting Seismic Waves Finding Epicenter
17
Detecting Seismic Waves
18
Detecting Seismic Waves First Motion Analysis
19
Detecting Seismic Waves First Motion Analysis -
Strike Slip Faults
20
Seismic Strength
  • Mercalli Intensity Scale
  • Richter Scale (Magnitude)
  • Moment Magnitude

21
Seismic Strength Intensity
  • Measure of severity of ground shaking
  • Decreases with distance from focus
  • Shallow focus (lt30km) gt deep focus (gt100km)
  • Greater on unconsolidated sediment than on bedrock

22
Seismic Strength Modified Mercalli Intensity Scale
1811 New Madrid Earthquake 1906 San Francisco
Earthquake
23
Seismic Strength Richter Magnitude Scale
24
Seismic Strength Richter Magnitude Scale
25
Seismic Strength Moment Magnitude
26
Effects
  • Ground Motion
  • Fire
  • Landslides
  • Liquefaction
  • Permanent Displacement of Land Surface
  • Tsunami

27
Earthquake Damage
Kobe, 1995
Loa Prieta, 1989
Nigata, 1964
Taiwan, 1999
Gujarat, 2001
San Fernando, 1971
28
Earthquake Damage Ground Motion and Rock Type
29
Earthquake Damage Ground Motion and Rock Type
Mexico City, 1985
30
Landslides
Guatemala, 1974
Alaska, 1964
31
Liquefaction
Collapse of beach road
Liquefaction 1989 -Loma Prieta quake
Sand blow at Oakland International Airport
32
Tsunamis
  • caused by
  • earthquakes
  • undersea landslides
  • icebergs falling from glaciers
  • undersea volcanic eruptions
  • asteroid impacts

33
Tsunamis
34
Tsunamis
35
Tsunamis
36
Detecting Tsunamis
Deep Ocean Assessment and Reporting of Tsunamis
(DART)
37
Tsunami Danger
Atlantic Coast of North America
38
Plate Tectonics
39
Tectonic Setting of Earthquakes
40
Tectonic Setting of Earthquakes
41
Benioff Zone
42
Earthquake Prediction
43
Earthquake Prediction
44
Earthquake Prediction
45
Earthquake Prediction
46
Earthquake Prediction Seismic Gaps
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