HOW DO EARTHQUAKES AFFECT SOCIETY?

STRUCTURAL FAILURE Buildings made from “hard” materials do not stand up well to earthquakes. Concrete, stone etc. are not good if they are not reinforced with steel

Wood is good!! It is more flexible. Tall buildings with steel structures work well because the metal is flexible. Some buildings are built on large rubber structures.

LAND AND SOIL FAILURE If the land slopes, earthquakes can cause giant landslides. These can cover houses and people. If the soil is saturated with water, the soil can act like quicksand which can cause landslides even is flater areas.

Wave size increases in soft materials like sand and other soils. The wave size decreases in rock Earthquakes can cause “fault scarps”. These are places where one side of the fault rises and the other sinks. ( Compression /Tension).

TSUNAMIS Tsunami’s are caused by fault scarps in the ocean The rise and fall along the fault lifts the water, causing a wave. 1

The wave may be small in the deep ocean As it approaches the shore, the water is less deep. This means that the wave rises up.

2

The map on page 514 in your book shows where earthquakes are likely to happen.

Earthquakes are predicted on past records. If an area has had an earthquake every 20 years in the past, statistically more likely to happen after another 20 years. San Francisco is due for a big earthquake, but no one knows exactly when it will happen

Strain build up is another factor in predicting earthquakes.

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