The document discusses earthquakes, including the 1960 Valdivia earthquake in Chile that was magnitude 9.5 and caused 6000 casualties and $800 million in damage. It describes how earthquakes are caused by the sudden release of energy along fault lines in the earth. Different types of seismic waves are discussed, as well as the Richter scale and Mercalli intensity scale used to measure earthquake magnitudes and effects. Damage from earthquakes can include physical impacts like landslides as well as structural collapse and loss of life.

2.  The 1960 Valdivia earthquake or Great Chilean
Earthquake
 May 22nd
, 1960
 Intensity – 9.5
 Casualties : 6000
 Damage : 800 million US$

21.  The shaking or trembling caused by the sudden
release of energy
 Usually associated with faulting or breaking of rocks
 Continuing adjustment of stress results in
aftershocks
 Most earthquakes are small and harmless, but rare
much larger ones can cause enormous damage and
loss of lives.
 California has dozens of earthquakes every day, so
we need to learn to live safely with them.

22. The Focus and Epicenter of an Earthquake
• The point within the earth
where faulting begins is
the focus, or hypocenter
• The point on the surface of
the earth directly above
the focus is the epicenter

23. Convergent Boundary

24. Divergent Boundary

25. Transform Boundary

26. Seismographs record
earthquake events
Earthquakes occur at
various depths in the earth.
At convergent plate
boundaries, focal depth
increases along a dipping
seismic zone called a
Benioff zone.

27.  Body waves
 P or primary waves
▪ fastest waves
▪ travel through solids,
liquids, or gases
▪ compressional wave,
material movement is
in the same direction
as wave movement
 S or secondary waves
▪ slower than P waves
▪ travel through solids
only
▪ shear waves - move
material perpendicular
to wave movement

28.  Surface Waves
 Travel just below or along the ground’s surface
 Slower than body waves; rolling and side-to-side
movement
 Especially damaging to buildings

29. Seismic wave behavior
 P waves arrive first, then S waves, then L and R
 Average speeds for all these waves is known
 After an earthquake, the difference in arrival times at a
seismograph station can be used to calculate the distance
from the seismograph to the epicenter.

30.  Richter Magnitude
 Richter scale measures
the total amount of
energy released by an
earthquake;
independent of intensity
 Amplitude of the largest
wave produced by an
event is corrected for
distance and assigned a
value on an open-ended
logarithmic scale
 For very large
earthquakes, a modified
Richter scale is used
that takes into account
the size of the failure
surface as well as the
amplitude of the seismic
waves

31.  Ground Shaking
 amplitude, duration, and damage increases in poorly
consolidated rocks

32.  The Richter magnitude scale was developed to
assign a single number to quantify the energy
released during an earthquake.
 The scale is a base 10 logarithmic scale.
 The magnitude is defined as the logarithm of the
ratio of the amplitude of waves measured by a
seismograph to an arbitrary small amplitude.

34.  An earthquake that measures 5.0 on the Richter scale has a
shaking amplitude 10 times larger than one that measures
4.0, and corresponds to a 31.6 times larger release of energy.
 Since the mid 20th century, the use of the Richter magnitude
scale has largely been supplanted by the
moment magnitude scale in many countries.
 The Richter and MMS scales measure the energy released by
an earthquake; another scale, the Mercalli intensity scale,
classifies earthquakes by their effects, from detectable by
instruments but not noticeable to catastrophic.

37.  Based on location
1. Interplate
2. Intraplate
 Based on epicentral distance
1. Local earthquake < 1o
2.
Regional Earthquake 1 - 10o
3. Teleseismic Earthquake > 10o
 Based on Focal depth
1. Shallow depth 0 - 71 km
2. Intermediate depth 71 – 300 km
3. Deep earthquake > 300 km

38.  Based on magnitude
1. Micro earthquake < 3
2. Intermediate earthquake 3 - 4
3. Moderate earthquake 5 - 5.9
4. Strong Earthquake 6 - 6.9
5. Major Earthquake 7 - 7.9
6. Great Earthquake > 8

46.  Physical Damage
* Landslides
* Tsunamis
* Fires
* Mudslides
* Liquefaction
 Structural Damage
* Buildings Collapse
* Roadways Collapse
 Emotional Damage
* Deaths

49.  Physical Damage
* Landslides
* Tsunamis
* Fires
* Mudslides
* Liquefaction
 Structural Damage
* Buildings Collapse
* Roadways Collapse
 Emotional Damage
* Deaths

52.  Physical Damage
* Landslides
* Tsunamis
* Fires
* Mudslides
* Liquefaction
 Structural Damage
* Buildings Collapse
* Roadways Collapse
 Emotional Damage
* Deaths

55.  Physical Damage
* Landslides
* Tsunamis
* Fires
* Mudslides
* Liquefaction
 Structural Damage
* Buildings Collapse
* Roadways Collapse
 Emotional Damage
* Deaths

59.  Physical Damage
* Landslides
* Tsunamis
* Fires
* Mudslides
* Liquefaction
 Structural Damage
* Buildings Collapse
* Roadways Collapse
 Emotional Damage
* Deaths

111.  What is richter scale?
 What is resonance?
 Explain following Failures:
 Soft Storey
 Plan/mass irregularities
 Floating column
 Short column
 Stair case damage
 Column failures
 Non-structural failures