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All about Earthquakes By 3 Students Table of Contents Chapter 1…………………………………………….Page 1 Chapter 2…………………………………………….Page 2 Chapter 3…………………………………………….Page 3 Chapter 1 There are three types of plate movements, the transform movement, the convergent movement, and the divergent movement. Transform movements occur when plates slide or grind past along transform faults. The San Andreas Fault is a good example of a transform fault. Friction doesn’t allow plates to simply glide past each other. When these transform movements slide past each other they can create massive earthquakes. Convergent movements occur when 2 plates slide towards each other forming either a subduction zone or an orogenic belt. Convergent boundaries are also known as destructive boundaries. A subduction zone is when a dense oceanic plate thrusts under the less dense continental plate. This can create a mountain chain or a chain of volcanoes. Divergent movements occur when two plates slide apart from each other. These are also known as constructive boundaries. This creates a space that is filled in with crustal materials such as magma and rocks. These are powered by hot spots and can make rift valleys. The average amount of distance a plate will move is 0.66 to 8.50 centimeters per year. Some plates like the Antarctic plate have a different speed of 2.05 centimeters per year. Plate’s size can also vary greatly, from a few hundred to thousands of kilometers across. The Pacific and Antarctic plates are among the largest. Plate thickness also varies from less than 15 km for oceanic plates to around 200 km or more for ancient continental plates. For example one part of the ocean can be down to 10 kilometers and some parts of land can be up to 70 kilometers. The 3 major layers of the Earth are the crust, mantle and inner/outer core. The crust is the Earths outer most layer. It can be up to 20 miles thick on continents and down to 5 miles thick in the ocean. Most earthquakes occur in the Earth’s crust. The Earth’s crust is thin and also brittle. The mantle is just below the Earth’s crust and extends all the way down to the core. The mantle is about 6 miles below the oceanic plates and 19 miles below the continental plates. The mantle is about 1800 miles thick and it takes up 80% of the Earth. The mantle is composed of very hot dense rock. The outer core has melted metals like nickel and iron. It is 1400 miles thick and it is so hot that the metals have melted. The inner core begins about 4000 miles below the crust and it is 800 miles thick. The metals in the inner core are not liquid but a solid because of all the pressure and heat. The ring of fire is a zone where earthquakes and volcanoes frequently happen. The ring of fire encircles a basin of the Pacific Ocean. It is shaped like a horseshoe and is 40,000 km long. Many series of oceanic trenches, island arcs and volcanic mountain ranges are within the ring. 90% of the world’s earthquakes and 81% of the larger ones occur within the ring. The ring of fire is where movement and collision of crustal plates occur. This is what causes the earthquakes to occur. An example of one of these movements is that the eastern region Nazca plate and Cocos plate subduct under the South American Plate. The Nazca plate is colliding with the South American Plate. Chapter Two There are probably three major places in California where there are tons of earthquakes. The San Andreas Fault along the west coast of California is probably the most places where earthquakes happen. The San Andreas Fault is the most studied fault in the world as well. The Geysers to the northeast is another place where a lot of earthquakes happen. The South East has a large area of faults such as the San Jacinto Fault, the Coyote Creek Fault, and the southern parts of the San Andreas Fault. A fault is place were the earths crust is open and splitting apart due to tectonic plate activity. The earthquakes happen because of the earths plates. The continents and oceans are floating on the top of the mantle. Sometimes the plates collide and rub against each other. This is where most earthquakes happen. California is right on the Ring of Fire, which is the Pacific plate colliding with other plates. The ring of fire is where most earthquakes in the world happen. In California’s case the North American plate is rubbing against the Pacific plate. When the plates collide the earth shakes and the earthquakes happen. California is on the San Andreas Fault. The Pacific plate is heading up and the North American plate is moving down. They meet at the San Andreas Fault. When they rub against each other they cause earthquakes. This means that California must be prepared. In 1906 a huge earthquake occurred along the San Andreas Fault. California was devastated since then more earthquakes happened. Now California is making more ways to avoid devastation. Chapter Three The first main earthquake danger is the effect of the ground shaking. Buildings can be damaged by the shaking itself or by the ground beneath them settling to a different level than it was before the earthquake (subsidence). Buildings can even sink into the ground if soil liquefaction occurs. Liquefaction is the mixing of sand or soil and underground water, or groundwater. The second main earthquake hazard is ground displacement or ground movement along a fault. If a structure is built across a fault, or a dislodging of the earths crust, the ground displacement during an earthquake could damage or rip apart the structure. The third and fourth dangers of earthquakes are flooding and fire. The flooding can occur when the earthquake breaks dams or levees along rivers. Fires can be started by broken gas lines and power lines, or tipped over wood or coal stoves. Most of the hazards to people are caused by man-made things. The real dangers to people are being crushed in a collapsing building, drowning in a flood caused by a broken dam or levee, getting buried under a landslide, or being burned in a fire. The first thing you should do before an earthquake happens is to have your shelves connected tightly to walls, and place heavy objects on lower shelves as well as storing breakable items in low, closed cabinets. You should also hang things like pictures and mirrors away from beds and anywhere people sit. Brace hanging light fixtures and repair known defective electrical wiring and gas connections. Strap your water heater to studs in the wall and bolt it to the floor. You can also repair any large existing cracks in walls or foundations. Store poisons such as pesticides and liquids used for cleaning, as well as flammable liquids, on bottoms shelves of latched cabinets. Then you should find a safe place in each room (under sturdy furniture, against inside walls, away from glass). Find safe places outdoors (away from buildings, trees, electrical lines, and bridges). It is really important to teach your family members how to turn off gas, electricity, and water. It would be a good idea to teach children how to dial 911 in an emergency. Have disaster supplies on hand (flashlight and extra batteries, battery operated radio, first aid kit with manual, emergency food and drinking water, non electric can opener, money, and sturdy shoes). Make an emergency communications plan in case family members are separated and need to be found. If you happen to get caught in an earthquake then it is very important to stay away from glass windows or statues. You should not be under any flimsy shelves either; they could easily fall on you and knock you unconscious. It is said that if you do not have a sturdy desk or anything like that, you should definitely try to find something sturdy enough to hold on to. You should never leave the house or structure you are currently in during heavy shaking. If you are in a town shopping it is the best idea to stay in that building unless there is an electrical or gas leak. Move to a clear area if you can safely walk. Avoid power lines, buildings and trees. If you’re driving, pull to the side of the road and stop. Avoid stopping under overhead hazards. If you are on the beach, move to higher ground. An earthquake can cause a tsunami. There are a couple of different types of things you should have during the emergency. In your drugs/medication pack you should have the following: Hydrogen peroxide to wash and disinfect wounds, antibiotic ointment, individually wrapped alcohol swabs, aspirin and non-aspirin tablets, Prescriptions and any long-term medications (keep these current),diarrhea medicine, and eye drops. Other things you should have are some dressings. Some suggestions for this subject are bandage strips, ace bandages, rolled gauve, adehsive tape roll, and cotton swabs. There are other things you should use to keep safe. If you want a list of these things you should use this website; http://www.bt.cdc.gov/disasters/earthquakes/supplies.asp Works Cited Chapter 1 Tectonic Plate, [www].http://www.crystalinks.com/tectonicplates.html. 6/5/08 Pacific Ring of Fire, [www]. http://www.crystalinks.com/rof.html. 6/5/08 Chapter 2 USGS, [www]. http://quake.usgs.gov/recenteqs/latest.htm. 6/5/08 Earthquake Map, [www]. http://www.crustal.ucsb.edu/scec/webquakes/. 6/5/08 Earthquakes for kids, [www]. http://earthquake.usgs.gov/4kids/ . 6/5/08 Chapter 3 1st question Earthquake Hazards, [www]. http://www.geo.mtu.edu/UPSeis/hazards.html. 6/5/08 2nd question Earthquakes, [www]. http://tremor.nmt.edu/faq/prepare.html. 6/5/08 3rd question How to Prepare, [www]. http://www.72hours.org/earthquake.html . 6/5/08 4th question Disasters, [www]. http://www.bt.cdc.gov/disasters/earthquakes/supplies.asp. 6/5/08