Earthquake Damage and Earth’s Interior

Factors contributing to damage

DurationIntensityBuilding Design – reinforced/flexible

buildings bestMaterials built on – hard, dense material

the bestLiquefaction - when loose sediments are

saturated with water, during an earthquake, shaking creates a liquid like material not able to support structure – structure sinks

Tsunamis – sea waves

caused by an earthquake that displaces the ocean floor vertically

water is pushed upwards and toward the land

speeds of 500-950 km/hrlow waves in open water – as wave nears

shore water builds upwardsTsunami warning system – world wide -

alerts about danger

Other Dangers

Fires - from broken gas pipes and falling power lines

Landslides – rock and soil slide downhill from shaking

Predicting Earthquakes

No predicting devicesOnly measurements – stress along faults,

water level in wells, gas emissions from fractures

Seismic gap – time between earthquakes

The Earth’s Interior

Knowledge of Earth’s interior comes from Earthquake waves

By measuring the speed of a wave - able to determine the composition of the Earth

P waves travel through liquids and solids

S waves travel only through solids

As P waves travel they bend as they enter new material - bending shows change of material

S waves not traveling through the outer core also shows change in material

Conclusion – Earth is made up of different states of material

Layers of the Earth

Crust: Thin rocky layer oceanic crust +/- 7 km thick continental crust 8km -75 km thick

Mantle: Solid, rocky shell – depth of 2890 km

80% of Earth’s volume

Core: Iron and nickel center Outer Core – 2260 km thick

- liquid - Earth’s magnetic field produced

here Inner Core – sphere with radius of 1220 km

- solid because of the pressure