Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
What is an Earthquake? An earthquake also known as a quake, tremor or temblor is an unpredictable event in which masses of rock shift below Earth's surface, releasing enormous amounts of energy and sending out shock waves that sometimes cause the ground to shake dramatically. http://www.scienceclarified.com/Di-El/Earthquake.html What causes Earthquakes? Earthquakes are caused when tension is released from the rocks in the Earth's crust and upper mantle. This tension is due to friction between what scientists believe are large 'plates' floating on magma on the Earth's surface. Sometimes earthquakes happen when the rocks in the earth's crust bend and break. This causes shock waves to travel on the earth's surface, resulting in widespread destruction. http://library.thinkquest.org/10136/earthquk/earttq.htm#what Where do earthquakes occur? Earthquakes usually occur in places where two plates meet, called faults. They are mostly generated deep within the earth's crust, when the pressure between two plates is too great for them to be held in place. The underground rocks then snap, sending shock waves out in all directions. These are called seismic waves. The point at which an earthquake originates on the surface is called the epicenter. http://library.thinkquest.org/10136/earthquk/earttq.htm#what Types of Earthquakes There are many different types of earthquakes these are tectonic, volcanic, collapse and explosion. The type of earthquake depends on the region where it occurs and the geological make-up of that region. http://scign.jpl.nasa.gov/learn/eq2.htm Tectonic Earthquake: earthquake that occurs when the earth's crust breaks due to geological forces on rocks and adjoining plates that cause physical and chemical changes. Volcanic Earthquakes: earthquakes that result from tectonic forces which occur in conjunction with volcanic activity. http://scign.jpl.nasa.gov/learn/eq2.htm Collapse Earthquakes: small earthquakes in underground caverns and mines that are caused by seismic waves produced from the explosion of rock on the surface. Explosion Earthquakes: earthquakes which are the result of the detonation of nuclear and chemical devices. http://scign.jpl.nasa.gov/learn/eq2.htm How are earthquakes measured? Earthquakes can be measured in several ways. The first is to describe the earthquake's intensity and the second type of measurement is the magnitude of the earthquake. Two scales are commonly used to measure earthquakes: the Mercalli Scale and the Richter scale. http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/LearnMoreAboutEarthquakes/tabid/256/Default.aspx The Richter Scale The Richter Scale measures the magnitude or amount of energy released by the earthquake. Magnitude does not depend on population and effects to ground structures, but rather on wave amplitude and distance. This is a measure of size for earthquakes based on recordings of ground motions by instruments. http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/LearnMoreAboutEarthquakes/tabid/256/Default.aspx The Mercalli Scale The Mercalli Scale measures the intensity of the earthquake that is, the impact of a quake on people and their property. This speaks to the observed effects of an earthquake over a limited geographical area. Intensity scales assign whole numbers usually from 1 to 12 to describe these observed levels of shaking. An intensity of 1 means the earthquake was not felt, while 12 means absolute and total destruction. http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/LearnMoreAboutEarthquakes/tabid/256/Default.aspx Earthquake preparedness tips Earthquakes can happen at anytime and anywhere. There is a chance, when an earthquake hits, that you may have a few seconds between the realization that this is an earthquake and the time when the shaking stops. If you know what to expect and what to do, you can make the right decisions that may mean the difference between injury, life or death. http://www.odpem.org.jm/DisastersDoHappen/TypesofHazardsDisasters/Earthquakes/ProtectYourselfFromanEarthquake/tabid/258/Default.aspx#What_to_do_During_an _Earthquake Duck, Cover and Hold Duck: get under a sturdy piece of furniture, making yourself into a little ball (do not duck under beds or other objects that could collapse). Cover: keep your head and eyes protected from falling or flying objects. Cover your head with one hand. Hold: with your other hand, hold onto the piece of furniture. If it moves, move with it. Stay under shelter until you are sure the shaking has stopped. When in a HIGH-RISE BUILDING, move against an interior wall if you are not near a desk or table. Protect your head and neck with your arms. Do not use the elevators. When OUTDOORS, move to a clear area away from trees, signs, buildings, or downed electrical wires and poles. When on a SIDEWALK NEAR BUILDINGS, duck into a doorway to protect yourself from falling bricks, glass, plaster and other debris. When DRIVING, pull over to the side of the road and stop. Avoid overpasses and power lines. Stay inside your vehicle until the shaking stops. When in a CROWDED OR PUBLIC PLACE, move away from display shelves containing objects that could fall. Do not rush for the exit. When in a STADIUM OR THEATER, stay in your seat, get below the level of the back of the seat and cover your head and neck with your arms. Aftermath of Haiti earthquake Jan 14, 2010 Aftermath of Haiti earthquake Jan 14, 2010 Chile quake February 27, 2010 quake February 27, 2010 When an earthquake strike: Be Bold, Drop, Cover, Hold.