Earthquakes 1. Earthquake: the shaking and trembling that result from the movement of rock beneath Earth’s surface. 2. Seismic waves carry the energy of the earthquake away from the focus, through Earth’s interior and across the surface. There are 3 categories of seismic waves; p-waves, s-waves, and surface waves. The 1st to arrive are the primary waves, or p-waves. P-waves are earthquake waves that compress and expand the ground like an accordion. S-waves or secondary waves are earthquake waves that vibrate from side to side as well as up and down. Surface waves move more slowly than p-waves and s-waves, but they can produce severe ground movements. Some surface waves make the ground roll like ocean waves. 3. Focus; the point beneath the Earth’s surface where rock that is under stress breaks, triggering an earthquake Epicenter: the point directly above the focus on the surface Fault: is a break in the crust where slabs of crust slip past each other. 4. Hazards of earthquakes; shaking of the earth, power lines fall, gas line burst, fires, and building falling. 5. To determine where an earthquake occurred you need to find the difference in the arrival of p-waves and s-waves from 3 different stations. Use the chart to determine the distance around the station center. Draw a circle around the station center. Where the 3 circles meet is where the earthquake occurred. Volcanoes 1. Shield Volcano; thin layers of lava pours out of a vent and hardens on top of a previous layer. The lava flows gradually build a wide, gently sloping mountain. Form from a hot spot. Quiet eruptions. Cinder Cone: when cinders erupt explosively from a volcanic vent, they pile up around the vent, forming a cone shaped hill. Composite: lava flow alternates with layers of ash, cinders, and bombs, which has both quiet and explosive eruptions. Tall cone shaped mountain. 2. Shield- quiet Cinder cone-explosive Composite- quiet and explosive 3. Most volcanoes occur along diverging plate boundaries, such as mid- ocean ridge or in subduction zones around the edge of oceans. Some volcanoes can form at hot spots. 4. High in silica: very thick, light colored, lower in temperature, cause explosive eruption Low in silica: thin, dark colored, hotter in temperature, cause quiet eruptions 5. Hot spring form when a body of water is heated up from magma. It makes it way to the surface through a crack in the rock. 6. Hazards of volcanoes lava, pyroclastic flow, fire, gases Weathering and Erosion 1. Mechanical/Physical weathering: the breakdown of rock into smaller pieces of the same material without any change in its composition Chemical weathering: the breakdown or decomposition of rock that takes place when minerals change through chemical processes. The agents of chemical weathering are water, oxygen, carbon dioxide, and acid rain. 2. The most important factors that determine the rate at which weathering occurs are the type of rock and climate. a. Climate- wet climates allow weathering to occur faster. Chemical in hotter temperatures and mechanical/physical in colder temperatures. b. Rock type the softer the rock such as Sedimentary the easier the breakdown the harder the rock such as metamorphic the hard it is to breakdown. 3. Release of pressure- as erosion removes material from the surface of a mass of rock; pressure on the rock below is reduced. This release of pressure causes the outside of the rock to crack and flake off like the layer of on onion. Ice wedging- when water freezes in cracks of rock, it expands and makes the crack bigger. Plant growth- root of trees and other plants enter cracks in rocks. As the root grows, the force the crack apart. Carbon dioxide- can mix with water and produce a weak acid which and destroy rocks. Water- will erode rock. Abrasion- sand and other rock particles that carried by wind, water, or ice can wear away exposed rock surfaces like sandpaper on wood. Animal action- animals that burrow in the ground loosen and break apart rocks in the soil. 4. Weathering: The process by which natural forces break down rocks. Erosion: The process in which sediment is picked up and moved from one place to another. Deposition: the process in which transported sediment is laid down. 5. Soil is a mixture of four material; weathered rock particles, organic matter, water, and air. Soil that forms in an area will depend on a number of factors which include: the kind of rock, the area’s climate, or overall weather pattern over time, the landforms in the area, such as mountains and valleys, the plant coverage, the animals and other organisms in the area, and time. 6. All mass movement/mass wasting is due to gravity. a. Slump- a mass of rock and soil that suddenly slips down a slope in one large mass. b. Creep- the very slow downhill movement of rock and soil. Can’t see happened, it occurs over a period of time. c. Rockslide/rock fall- individual blocks of rock drop suddenly and fall freely down a cliff or steep mountain. Large mass of rock slides down the hill or mountain as a unit. d. Mudflow/mudslide- a mixture of rock, soil, and plant. 7. Moving water is the major agent of erosion that shaped Earth’s land surface. A river creates valleys, waterfalls, floodplains, deltas, alluvial fans, meanders, and oxbow lakes. 8. The 2 processes by which glaciers erode the land are plucking and abrasion. Plucking picks up rocks by freezing to the bottom of the glacier. Abrasion is when small rock fragments are carries in the glacier and wear away rock. 9. Wave erosion is caused by ocean water shaping and wearing away the shore line. a. Longshore drifts is the zigzag movement of sand along the beach. b. Longshore currents is the movement of water along a shore as waves strike the shore at an angle. c. Barrier island narrow island that develops parallel to a coast, due to the deposition of sand. Waves can also cut caves into the land and create sea pillars. 10. Wind erosion shapes the land by the wind blowing particle of sand. This can create dunes, which is a mound of sand built up by wind. It can also cause abrasion which wears away rock. Weather 1. Atmosphere- the layer of gases that surrounds the planet. a. Oxygen=21% b. Nitrogen =78% c. Other gases such as water vapor, carbon dioxide, helium, methane=1% Earth’s atmosphere is made up of nitrogen, oxygen, carbon dioxide, water vapor, and many other gases, as well as particles of liquids and solids 2. Air has pressure because it has mass. Dense, cool, air exerts more pressure than less dense warm air. The result of weight of a column of air pushing down on an area. More pressure at the bottom of a mountain than on the top. 3. A barometer is used to measure air pressure. 4. There are 4 main layers of the atmosphere that are classified according to changes in temperature. a. Troposphere- where weather occurs, layer that we live in. b. Stratosphere- where you would find the ozone c. Mesosphere- where meteoroids burn up d. Thermosphere 5. The ozone layer absorbs ultraviolet radiation. 3 atoms of oxygen. It absorbs energy from the sun; the energy is converted into heat, warming the air. 6. Heat is transferred by radiation conduction, and convection. a. Radiation- direct transfer of energy by electromagnetic waves b. Conduction- direct transfer of heat from one substance to another substance that it is touching. c. Convection- transfer of heat by the movement of a fluid (gas or liquid) 7. Winds are caused by a difference in air pressure. The difference in air pressure is caused by unequal heating of earth’s surface. 8. Cold air masses tend to be more dense than a warm air mass, due to the molecules being closer together. Since the cold air mass is more dense it tends to sink and go under a warm air mass. 9. Local winds are caused by unequal hating of Earth’s surface within a small area. Sea Breezes- a wind that blows from a lake or ocean onto land, this occurs in daytime due to earth’s surface heating up more quickly. Land Breezes- the flow of air from land to a body of water. This occurs at night because the land tends to release it heat more quickly than the water. Global winds- winds that blow steadily from specific directions over long distance. This is created by unequal heating of Earth’s surface. They are trade winds, prevailing westerlies, and polar easterlies. 10. Coriolis Effect- the way the earth’s rotation makes the wind curve. In the Northern hemisphere the winds gradually turn toward the right and in the southern hemisphere the gradually curve to the left. 11. Cumulus- looks like rounded piles of cotton. Means heap or mass, usually indicate fair weather, they may grow in height. Stratus- forms in flat layers usually covers the entire sky, may produce drizzle, rain, or snow, they are low level clouds. Cirrus- wispy, feathery clouds, form at high levels where temperatures are very low. Mostly made up of ice crystals. 12. Maritime Tropical- warm, humid air masses form over oceans near the tropics. In the summer it brings hot, humid weather. In the winter it can bring heavy rain or snow. Maritime Polar- cool, humid air masses that form over the icy cold North Pacific and North Atlantic oceans. Continental Tropical- hot, dry air masses that form only in the summer over dry masses of the southwest and northern Mexico. Continental Polar- large polar air masses form over central and northern Canada and Alaska. They bring cool and cold air. The air masses can form near the Arctic Circle and can bring bitterly cold weather with very low humidity. 13. Thunderstorms form within large cumulonimbus clouds. They form on hot humid afternoons in spring and summer. 14. Parts of a hurricane eye, which is the calm winds and the eye wall which is where the high winds and storms come from. 15. Tornado Watch” - tornadoes possible in your area. “Tornado Warning” - tornado has been seen in the sky or on a weather radar. The safest place during a tornado is a basement of a well-built building. Move to the middle of the ground floor. Stay away from windows and doors. Lie flat on the ground under sturdy furniture. Move to a building or lie flat in a ditch 16. A meteorologist is someone who studies weather. 17. The reason why we have season is due to the fact that the earth is tilted. During the summer the earth’s northern hemisphere is tilted toward the sun. 18. Climate refers to the average year after year conditions of temperature, precipitation, winds, and clouds in an area. 19. Two main factors of determining the climate of a region is temperature and precipitation.
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