Section 3: Earthquakes and Society Chapter 12 – Earthquakes Section 3: Earthquakes and Society

Section 3 Objectives Discuss the relationship between tsunamis and earthquakes Describe two possible effects of a major earthquake on a building List three safety techniques to prevent injury caused by earthquake activity Identify four methods scientists use to forecast earthquake risks

TSUNAMIS!!! Giant ocean waves that form after Volcanic eruptions Submarine earthquakes Underwater landslides

Destruction to Buildings and Property Amount of earthquake damage to buildings depends on several factors Structure of buildings – Weak walls that are not constructed to withstand swaying motion of ground Very tall buildings may sway and topple over, damaging the buildings around them Building foundations Loose soil and rock is more likely to be damaged than solid ground Liquefaction

Earthquake Safety Before After During Supplies of food, water, batteries, flashlights, and radio Have emergency earthquake drill plans in place ( how to turn off gas, water, and electricity) During Stay calm and move to a safe position inside along the inner walls. Stay away from objects that may fall or topple over. After Be cautious, check for fire and other hazards. Wear shoes near broken glass. Avoid downed powerlines and any other wires. People who live near active faults should follow these rules to prevent death, injury, and property damage

Earthquake Warnings & Forecasts Unpredictable Scientists can use past earthquakes to predict where more earthquakes might occur, but cannot predict when the might occur Seismic gap – area of a known fault that hasn’t had an earthquake in awhile, but has the potential for a large, violent earthquake Foreshocks can precede a larger earthquake by a few seconds or weeks. Not always an efficient warning system

Changing Rocks & Seismic Gaps Measurements of slight tilting of the ground, areas of strain and cracks, and gas seepage are used to monitor areas for potential seismic activity Scientists hope to use this information to one day better predict major earthquakes in order to save lives and reduce property damage