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Write a 4 line response to this … …. Earthquakes don ’ t kill people, buildings do!!!. AGREE OR DISGAREE?. Learning Objectives: To understand the features of an earthquake. To appreciate the differences in earthquake impacts around the world.
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Write a 4 line response to this …… Earthquakes don’t kill people, buildings do!!! AGREE OR DISGAREE? Learning Objectives: To understand the features of an earthquake. To appreciate the differences in earthquake impacts around the world. To understand how people can prepare for earthquakes.
In an average year, Approximately 12 million earthquakes occur around the world Only about 100 of these Have a significant impact
What is an earthquakes • An earthquake is a sudden release of energy, caused by the earths plates rubbing together. • Where plates move against each other, pressure builds up between them. Eventually the pressure between these plates exceeds the friction holding them still and the earth’s plates jerk suddenly. • This sudden release of energy sends out huge pulses known as ‘seismic waves’ which cause the ground to shake.
Epicentre Seismic waves Fault /boundary Crust Focus
Effects of earthquakes The effects of earthquakes can be divided into 2 categories: • Primary effects – immediate consequences of the quake • Secondary effects – long term consequences of the quake which come about days, weeks and even months after the actual quake
Primary effects Secondary effects Diseases can spread very quickly in the unsanitary conditions often left behind by massive earthquakes. Water becomes contaminated very quickly, and in Less Economically Developed Countries (LEDC's) especially; access for the medical services can be badly hampered by the damage caused by the quake. Buildings collapse. Roads and bridges being destroyed and railway lines being buckled. Fires: usually from ruptured gas lines. This was the main cause of death and damage after the San Francisco earthquake in 1906. Tidal waves: A tidal waves caused by an earthquake is called a tsunami. They can travel very quickly across entire oceans, before engulfing land 1000's of miles away. Landslides can often be triggered by earthquakes, causing huge amounts of material to be moved very quickly. This is actually what occurred just before the volcanic eruption on Mt. St. Helens. They are most likely to occur where the land is steep, saturated or weak.
Liquifaction • https://clipbank.atomwide.com/espresso/clipbank/servlet/asset?assetID=13453 • Watch the clip and add to your table. Ensure you explain what it is.
Big town Small Village
Good response team Basic response team
Economic development (is the country an LEDC or MEDC) Depth of earthquake (a shallow focus will cause more damage) Magnitude Factors affecting damage caused by earthquakes Strength of buildings Response Time of day Preparation Population
How are earthquakes measured? • The power of an earthquake is known as its magnitude and is measured on a scale called the Richter Scale. (STICK IN COPY OF THE RICHTER SCALE) • The magnitude of an Earthquake is measured using sensitive instruments called seismometers which measure the amount the ground shakes.
The Three P’s Policy Predict There may be many pre-shocks before an earthquake that can be measured on a seismograph. Animals often act strangely for examples dogs will howl before an earthquake. All buildings must comply with strict earthquake planning regulations. Existing buildings, roads and bridges should be strengthened. Protect Prepare disaster plans. Organise and prepare hospitals and evacuation centres. Organise emergency supplies. Prepare
Page 128-129 • What can people do in earthquake prone areas? • Can scientists predict earthquakes?