Earthquake Hazards and Safety CHAPTER 2 SECTION 3

Earthquake Hazards and Safety CHAPTER 2 SECTION 3 PAGES 72 -77

How Damage is Caused Severe shaking from seismic waves S waves cause the most damage Earthquakes can also cause landslides or avalanches

Local Soil Conditions When waves move from rock to soil they transmit their energy The denser the soil the more violent the shaking Soil will shake harder than rock Houses built over sandy soil will shake and rattle more than houses built over solid rock

Liquefaction Occurs when shaking suddenly turns loose, soft soil into liquid mud Usually occurs where soil is full of moisture As ground gives way, buildings sink and pull apart Can cause landslides

Aftershocks Occurs after a larger earthquake in the same area Can strike hours, days, or months later Can be serious or just little vibrations

Tsunamis Plates cause ocean floor to rise slightly and push ocean water out of the way Spreads out across the ocean from the epicenter Waves are very far apart and not much higher than normal waves in the middle of ocean Waves get closer together and much higher as they get closer to land Some can even get as high as a 6 story building

Making Buildings Safer Newer buildings have to be made stronger and more flexible Has to be able to withstand the violent shaking Has to be able to twist and bend without breaking

Choice of Location Steep slopes lead to more landslides Filled land can shake violently Don’t build near an earthquake fault As waves move through the surface they loose energy the further they get from epicenter Further away you live from a fault the less damage you would normally see

Construction Method Brick and wooden buildings will collapse easier unless they have reinforced walls Plywood sheets can be used for wooden frames Homes built on soft grounds are anchored to solid rock Bridges are built on supports that go down through soft soil to solid ground Base-isolated building Designed to reduce the amount of energy that reaches the building

Protecting Yourself During an Earthquake Best way is to drop, cover, and fold Inside Under a sturdy table, near an inside wall with nothing hanging on it, or doorframe Outside Open space away from cars, buildings, and power lines A park If you live in a region where earthquakes are likely to occur you should keep an emergency kit on hand Should include canned food, water, first aid supplies Store where it is easy to reach