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What boundary? A destructive plate boundary A constructive plate boundary A conservative plate boundary A linear feature between 5 tectonic plates that move away from each other A Plate boundary where the plates move alongside each other causing earthquakes A plate boundary where the plates move towards each other causing earthquakes and/or volcanoes EARTHQUAKES What is an Earthquake? • An earthquake is the result of a sudden release of energy in the Earths crust that creates seismic waves. Epicentre – The location on the surface directly above the focus of an earthquake Focus – the location within the earth where underground rocks move and sends out earthquake waves Seismic Waves – shock waves created at the focus and sent out in all directions through the earth Fault a crack in the earth where movement occurs EPICENTRE SEISMIC WAVES FOCUS FAULT How do we measure Earthquakes? The Richter Scale measures the energy released by an earthquake at its focus. The energy is measured using a Seismograph Earthquakes are measured using machines called Seismometers. The depth of the wave is its amplitude. The more the ground shakes, the greater the amplitude of the wave. So the bigger the vibration, the longer the spike on the graph, and the more damage it will cause. The amount of energy released in an earthquake is called its magnitude This is measured on the Richter Scale An increase of 1 on this scale means a 30 fold increase in their energy The Mercalli Scale • The Mercalli Scale describes the damage caused by the earthquake • I Barely felt • II Felt by a few sensitive people, some suspended objects may swing • III Slightly felt indoors as though a large truck were passing • IV Felt indoors by many people, most suspended objects swing, windows and dishes rattle, standing cars rock • V Felt by almost everyone, sleeping people are awakened, dishes and windows break • VI Felt by everyone, some are frightened and run outside, some chimneys break, some furniture moves, objects fall from shelves, slight damage, plaster on walls might crack • II Considerable damage in poorly built structures, felt by people driving, most are frightened and run outside, loose bricks fall from buildings • VIII Slight damage to well built structures, poorly built structures are heavily damaged, walls, chimneys, monuments fall • IX Underground pipes break, foundations of buildings are damaged and building shift off foundations, considerable damage to well built structures • X Few structures survive, most foundations destroyed, water moved out of banks of rivers and lakes, avalanches and rockslides, railroads are bent • XI Few structures remain standing, total panic, large cracks in the ground • XII Total destruction, objects thrown into the air, the land appears to be liquid and is visibly rolling like waves The Haiti Earthquake On 12 January 2010, a magnitude 7 earthquake hit Haiti at 16:53 local time. The earthquake’s epicentre was 25 km west of Port-auPrince, the capital. Most people, businesses and services were located in the capital. Haiti lies right on the boundary of the Caribbean and North American plates. There was slippage along a conservative plate boundary that runs through Haiti. • • • • • • • • Social impacts of the earthquake (effects on people) 3 million people affected. Over 220,000 deaths. 300,000 injured. 1.3 million made homeless. Several hospitals collapsed. http://www.youtube.com/watch?v=CtBXTvtFaCU http://youtu.be/OTa65aIifto • • • • • Economic impacts of the earthquake (effects on money and jobs) 30,000 commercial buildings collapsed. Businesses destroyed. Damage to the main clothing industry. Airport and port damaged. • Many of the effects were immediate or primary, eg injuries from falling buildings. Some secondary effects didn’t happen until many months later, eg cholera outbreaks. The effects of this earthquake were particularly bad because of the following reasons: • • • • There were very few earthquake-resistant buildings. Buildings and other structures were poorly built. The epicentre was near to the capital. There were few resources to rescue or treat injured people.