DRRR Unit II Exploring Earthsdtrttttth Hazards.pptx

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1. Earthquake Hazards What Is An Earthquake? It is the perceptible shaking of the surface of the Earth, resulting from sudden release of energy in the Earth’s crust that creates seismic waves. The EARTH The outmost layer of the Earth is broken into pieces. These pieces called “ PLATES” are moving away or toward each other.

2. * How Do Plates Move? Plates at our planet's surface moves because of the intense heat in the Earth’ s core that causes molten rock in the mantle layer to move. It moves in a pattern called a convection cell that forms when warm materials rises, cools, and eventually sink down. As the cooled material sinks down , it is warmed and rises again.

3. > New parts of a plate rise because they are warm and the plate is thin. As hot magma rises to the surface at spreading ridges and forms new crust, the new crust pushes the rest of a plate out of its way. This is called ridge push .

4. TYPES OF NATURAL EARTHQUAKES 1. TECTONIC  Earthquake produces by sudden movement along faults and plate boundaries. 2. VOLCANIC  Earthquakes produces by movement of magma beneath volcanoes.

5. WAYS OF DESCRIBING THE STRENGTH OF AN EARTHQUAKE: INTENSITY  perceived strength of an earthquake based on relative effect to people and structures; generally higher near the epicenter. 2. Magnitude  based on instrumentally derived information and correlated strength with the amount of total energy released at the earthquake’s point of origin.

6. HOW DO SEISMIC SHAKE THE GROUND? There are three main types of Seismic Waves: a.) P waves (Primary or Compression Waves )- these are the fastest and the first to arrive after an earthquake or other seismic event. They are longitudinal waves that propagate through the earth, compressing and expanding the material in the direction of their movement. b.)