1. 8.3 Earthquakes

2. Earthquake Hazard Earthquake hazard - is a measurement of how likely an area is to have damaging earthquakes in the future. ◦ Determined by past and present seismic activity.

3. Earthquake Hazard

4. Earthquake Forecasting Seismologists are not able to predict when earthquakes are going to occur. ◦ seismologists have discovered patterns in earthquakes which allow them to predict when they may occur.

5. Strength and Frequency The strength of an earthquake is related to how often they occur.  Stronger = Less Frequent  More Frequent = Weaker

6. Strength and Frequency

7. The Gap Hypothesis Gap hypothesis – a hypothesis that states that sections of active faults that have had relatively few earthquakes are likely to be the sites of strong earthquakes in the future. Seismic Gap – areas along a fault where relatively few earthquakes have occurred.

8. Earthquakes and Buildings Retrofitting – the process of making older structures more earthquake resistant. A common way to retrofit an older home: ◦ Securely fasten it to its foundation. ◦ Steel can be used to strengthen structures made of brick.

9. Earthquake – Resistant Buildings

10. Preparing for an Earthquake Before the Shaking Starts ◦ Safeguard your home against earthquakes.  Put heavier objects on lower shelves.  Have your home strengthened. ◦ Find safe places within each room of your home and outside. ◦ Plan a safe meeting space after the earthquake. ◦ Store water, food, fire extinguisher, flashlight, radio, medicines, and a first aid kit in a place you can access after the quake.

11. When the Shaking Starts Indoors ◦ Crouch or lie face down under a table or desk in the center of a room. Outdoors ◦ Lie face down away from buildings, power lines, and trees and cover your head with your hands. Car ◦ Stop the car and remain inside the car.

12. After the Shaking Stops Remove your self from immediate danger. ◦ Calm down and get your bearings as quickly as possible. Only return home when you are told that it is safe to do so by someone in authority. ◦ aftershocks may cause more damage to structures.

13. End of Chapter 8