AIM: How do we determine earthquake risk, the different kinds of earthquake damage, how to prepare for an earthquake and how to design safer buildings?

OBJ: Given notes SWBAT explain how we determine earthquake risk, the different kinds of earthquake damage, how to prepare for an earthquake and how to design safer buildings with 70% accuracy

DN: Text, read p. 68-73.

ACT: Introduction to earthquake risk, kinds of earthquake damage, earthquake safety (preparation), designing safer buildings.

HW: Complete Skills and Graphing I Packet; Study for Tectonics Exam, Feb 25

Geologists can determine earthquake risk by locating active faults and where past earthquakes have occurred.

In the US, earthquake risk is highest along the Pacific coast in California, Washington and Alaska. In California, the active San Andreas Fault often produces earthquakes. In Washington and Alaska, earthquakes are occurring along active subduction zones.

The eastern US has a low risk of earthquakes because this region is far away from plate boundaries.

How Earthquakes Cause DamageThe cause of earthquake damage is due to shaking, liquefaction, aftershocks and tsunamis.

Shaking: produced by S-waves and surface waves can trigger landslides, avalanches; damage or destroy buildings, bridges; topple utility/electrical poles and fracture gas/water mains. Loose soil shakes more violently than solid rock so that a house built on sandy soil will shake more than a house built on solid rock.

Liquefaction: produced by violent shaking which turns loose, soft soil into a liquid mud causing buildings to sink and pull apart.

Aftershocks: an earthquake that occurs hours, days, (even months) after a larger earthquake in the same area.

Tsunamis: a large tidal wave produced by water displacement from a submarine earthquake on the ocean floor.

Shaking & Aftershocks

Oh s _ _ t!!!Talk about a bad day!

Honey,I can see into Ms. Robinson’s bathroom. She is taking a shower

right now.

Tsunami

Tsunami

Yo! Tony,You were telling me you love to surf. Take a look outside your window.

Steps to Earthquake SafetyThe main danger is from falling objects, broken gas/water mains (fire, flooding), electrical poles (electrocution). DROP, COVER, HOLD

1) Crouch under a sturdy table or desk

2) Cover your head with your arms and Hold on; crouch against an inner wall. Keep away from hanging objects, windows, furniture; stay indoors

3) If outdoors, move to an open field away from trees, buildings, power lines/poles, vehicles.

4) Prepare first aid kit, water, canned food, radio

Designing Safer BuildingsTo reduce earthquake damage, new buildings must be made stronger and more flexible. Example: fasten bookshelves, bolt house to foundation, metal

connectors on house frame, plywood panels inside walls, metal brackets around chimney.

New homes built on soft ground should be anchored to solid rock below the soil. Bridges and highway overpasses can be built on supports that reach solid bedrock below.

cross- braces

Base Isolators

Base Isolators

Base-isolated building rests on huge shock-absorbing rubber pads or springs to absorb the violent shaking.

Older buildings can be modified to withstand strong quakes. Shear walls, tension ties, base isolators, cross braces, dampers and flexible pipes are used to construct seismic-safe buildings.

Flexible joints on gas and water mains (pipes) and automatic shut-off valves can cut off gas and water flow to prevent fires and electrocution.

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Flexible Joints