Earthquake Hazards and Safety Inside Earth Chapter 2.3 Pages 72-77
How Earthquakes Damage • Severe shaking produced by seismic waves can damage or destroy buildings and bridges • Topple utility poles • Fracture gas and water mains • S-Waves side to side and up/down motion can tear a building apart.
Local Soil Conditions Loose soil shakes more violently than surrounding rock A house built on solid rock will shake less than a house build on sandy soil.
Liquefaction Click to see animation • Occurs when the violent shaking suddenly turns loose, soft soil into liquid mud • Likely where soil is full of moisture • Buildings sink and pull apart • Can trigger landslides.
Christchurch Earthquake • Occurred in New Zealand in February, 2011 • Magnitude 6.3 Aftershocks of a 7.1 quake from September of 2010 • Strike-slip fault
Aftershocks Smaller earthquakes that follow large earthquakes Up to 1,000 per day can strike May strike hours, days or months later.
Tsunamis Click for animation Huge ocean waves caused by underwater earthquakes or landslides.
Tsunamis • Displaces water and forms a large ocean wave • Waves travel at speeds up to 750km/h or 500mph • Wave height is low until it reaches land • Six story building (30ft) • Threatens coast lines.
Making Buildings Safer To reduce damage new buildings must be made stronger and more flexible. Older buildings must be modified to withstand stronger quakes.
Choice of Location Steep slopes pose the danger of landslides Filled land (loose soil) can shake violently Avoid building near faults.
Construction Methods • Anchor buildings and road supports into solid rock below • Base-isolated buildings • Rests on shock absorbing rubber pads or springs • Allows the building to move back and forth gently.
Protecting Yourself Most danger is due to falling objects Stop, Cover and Hold Stay along an inner wall and cover your head and neck.
Protecting Yourself Avoid windows, mirrors and furniture that may fall over Make an earthquake kit- with first aid supplies, canned food and water.
Protecting Yourself • If outside… • Move to an open area away from falling objects • Power lines • Trees • Buildings • Sit down to avoid being thrown down.
New Madrid • Science & Society Discussion on page 82 • Population: 17,589(Public data info Google) • Education: 16 schools in county (Wiki) • Estimated Local Tax Income: $75,000,000 (Factfinder.Census.gov) Liquefaction in New Madrid
New Madrid Known Costs: • $10,000 per home (Pop. Of 17,589) • Estimated $58,630,000 to insure all citizens • $5,000,000 per medium sized school (16) • Estimated $80,000,000 What other costs might be of concern? Costs courtesy of Earthquake Safety Retrofitting and the reports by the National Post (April, 2011)