Earthquakes and Society

1
Earthquakes and Society

• Chapter 8
• Section 3 Notes

2
Earthquake Hazard

• Earthquake Hazard tells how likely a place is to
  ever have an earthquake.
• The level of earthquake hazard is determined by
  how many earthquakes have already been in that
  same area.

3
Predicting an Earthquake

• There are two ways seismologists have found to
  determine whether an earthquake will occur in a
  specific spot. They are
• STRENGTH AND FREQUENCY
• THE GAP HYPOTHESIS

4
Strength and Frequency

• Seismologists have discovered that the strength
  of an earthquake is related to how often they
  occur in the same spot.
• A strong earthquake (magnitude6.5) will occur
  about
• 800 times each year!!
• A very minor earthquake (magnitude2.7) will
  occur about 365,000 times each year!!

5
The Gap Hypothesis

• The Gap Hypothesis states that sections of active
  faults that have had relatively few earthquakes
  are likely to be the sites of strong earthquakes
  in the future.
• Places along a fault that have not had many
  earthquakes are called seismic gaps.

6
Science Humor

• What do you get when a cow is caught in an
  earthquake?

A MILKSHAKE
7
How To Make an Earthquake-Resistant Building

• a Mass Damper-a weight placed in the roof of a
  building that will shift during an earthquake to
  counteract the movement.
• steel cross-braces-placed between floors to
  counteract the pressure that pushes and pulls
  during an earthquake
• flexible pipes-prevents water and gas lines from
  breaking during an earthquake

8
How to Make a Earthquake-Resistant Building

• 4. An active tendon system-works like a mass
  damper in the basement of the building. It
  shifts the weight of the building to counteract
  movement during earthquakes.
• 5. Base Insulators-act as shock absorbers,
  absorbing seismic waves so they dont travel
  through the building.

9

• Click Here for
• Earthquake Clip

10
Are YOU Prepared?

• PLAN AHEAD-
• Move heavier things to bottom shelves, so they
  wont fall off during an earthquake.
• Have your family come up with a meeting spot
  for everyone to go after an earthquake.
• Store non-perishable food, water bottles, fire
  extinguisher, flashlight with batteries, and a
  first-aid kit in a safe place.

11
Are YOU Prepared? (cont)

• During the Earthquake-
• If you are indoors, get under a table or desk in
  the center of a room
• If you are outside, lie face down away from
  buildings, power lines, and trees. Cover your
  head with your hands.
• If you are in a car, stop driving and remain
  outside.

12
Are YOU Prepared? (cont)

• The Aftermath-
• Calm down, get your bearings, remove yourself
  from immediate danger (like downed power lines,
  broken glass, or fire hazards).
• There could be an aftershock-be prepared.