JLKP+2.3

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 * Earthquake Hazard and Safety** (back to to homepage)


 * Vocabulary**


 * liquefaction**-only occurs when the shaking of an earthquake suddenly makes loose soft soil into liquid mud
 * aftershock**- a smaller earthquake that occurs after a larger earthquake
 * tsunami**- a huge wave caused by underwater earthquakes
 * base-isolated building**- a structure that is mounted on bearings designed to take up the energy of an earthquake


 * Outline**


 * **How Earthquakes Cause Damage**
 * S waves cause severe damage to the epicenter
 * S waves put enough force to tear buildings apart
 * *Local Soil Conditions*
 * when seismic waves move from hard soil to soft soil, they transmit their energy
 * the loose soil shakes more than the surrounding rocks
 * the thicker the soil, the more violent the shaking will be
 * *Liquefaction*
 * the process that changes loose soil into liquid mud
 * can trigger land slides
 * *Aftershocks*
 * occurs after bigger earthquake
 * may strike minutes, hours, days, and even months later
 * *Tsunami*
 * underwater earthquakes
 * spreads out to the ocean from Earth's epicenter
 * the distance between wave of tsunami is 100~200 kilometers
 * **Making Buildings Safer**
 * must be flexible and strong
 * older building s must be modified to withstand stronger quakes
 * *Choice of Location*
 * steep slope pose to the danger of landslides
 * filled land shakes violently
 * should avoid building structures near fault lines
 * the farther from the fault the building is, the less it will shake during a quake
 * *Construction Methods*
 * brick and wood framed buildings may collapsed if not reinforced
 * sometimes plywood sheets are used for reinforcement
 * new houses built on soft ground should be anchored to solid rock beneath soil
 * use base-isolation bearings to absorb energy of earthquake
 * **Protecting Yourself During an Earthquake**
 * **best way is to** drop, cover, hold**
 * crouch beneath sturdy table so it doesn't slide away and hit someone
 * desk or table will provide protection for the head
 * if no desk, crouch against inner wall
 * if outdoors, avoid vehicles, trees, power lines,trees and buildings especially ones with brick chimneys or brick walls

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