earthquakes

What is an earthquake?

It occurs when there are sudden and rapid vibrations occurring within the earths crust caused by a sudden release of energy due to earth's movements

The source of the earthquake within the earth's crust is

Focus/ focal point/ hypocenter

The point directly above the hypocenter is the

Epicenter

Name the 3 depths of an earthquake

Shallow intermediate and deep

Shallow

Focal is about 60km deep

Intermediate

60 -300 km deep

Deep

Anything 700km and over

Seismometer

Instrument used to measure the intensity of an earthquake which is then recorded on a seismograph

The magnitude of an earthquake can be recorded using which two scales

Richter scale (1-10) or the mercalli scale (1-12)

Effects of Earthquakes

Loss of life and property, tsunamis, landslides, liquefaction and fires

Liquefaction

During shaking areas comprising of loose unsolidated material tend to settle.it land level falls below water tables it behaves as a liquid.in coastal areas the land slumps into the sea eg. Port Royal 1692.

Loss of life and property

Poorer countries which lack building code are more vulnerable cg. Haitian earthquake 2010 up to 300,000 people died.many buildings collapse trapping und killing people which adds to the death toll.

Tsunamis

These are earthquake generated waves caused by displacement along the sea floor eg. 2004 Indonesian tsunamis.

Landslides

This can block roads making them impassible. Villages and towns can be buried under ruble and tons of debris. can block rivers and valley areas to form quake lakes

Fires

This can occur when gas lines burst, sparks from broken electrical wires can ignite escaping gases. Eg. The great Fire of San Francisco 1906 with intensity 7.8 which left 3000 people dead.

What can be done as a protective measure during an earthquake?

Drop, cover and fold/ triangle of life and regular earthquake drills in offices, schools etc.