Earthquake Destruction and Dangers

Major causes of earthquake damage Landslides and liquefaction Aftershocks Tsunamis

Landslides Movement of material down a slope, especially… – on steep slopes – when saturated land is shaken violently

Liquefaction Loosely packed soil turns into mud. Most likely to occur in soil saturated with water. Liquefaction animation

Aftershocks Smaller earthquakes that occur after a larger earthquake in the same area They can occur hours, days, or months later Buildings already weakened by the original earthquake can topple during aftershocks

Tsunami A wave set off by an underwater earthquake Earthquake jolts the ocean floor; pushes water out of the way Displaced water forms large waves (tsunamis) – In the open ocean, height of wave is not significant – As the wave gets closer to land, water gets more shallow, pushes up into a tall wall ≈100 ft YouTube: CBS News Asian Tsunami YouTube: Tsunami Animation

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How do we prepare? Base-isolated buildings – Buildings rest on shock absorbing springs that allow the building to move without violently shaking

Protecting Structures

How do we prepare? Base-isolated buildings – Buildings rest on shock absorbing springs that allow the building to move without violently shaking Warning systems – Monitoring faults and waves

Instruments for monitoring faults Creep meter – measures HORIZONTAL movement along a fault line through movement of a wire across the fault Tiltmeter – measures VERTICAL movement, works like a carpenter’s level Satellites – Measure VERTICAL changes in the distance between the satellite and ground Faults & Earthquakes

Fault monitoring instruments Creep meterTiltmeter

Instruments for monitoring tsunamis Tsunami detection buoys – 39 stations collect seafloor height, temperature, pressure Warning centers – If a tsunami is generated, they issue advisories, watches and warnings

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