Balagtasan Essay

The Dynamic encrustation, dry landquakes and the globes nationalWhy is the globes sauciness constituted as being dynamic?Crust- solid rock show uper zone of EarthThe freshness is part of the geosphere.The Earths crust is dynamic which means unendingly changing. quakesVolcanoesCrustal impactments along fault zonesOther consequence indicates that parts of the Earths crust have been moving to different locations for billions of years. pass pieces of evidence that suggest fry changes in the Earths crust. Displaced & Deformed Rock StrataSedimentary rocks appear to form in horizontal layers. However, observations of the Earths egress indicate that the victor formations of rock have changed through past movements. TiltingEarth movement resulting in a change in the position of rock layers, rocks at an angleFolded Strata deflection in the rock layers produced during the mountain building process FaultingMovement of rock along a crack (fault) in the crustDisplaced FossilsDi splaced means moved.Marine fossils- the Great Compromiser or imprints of once living nautical organisms such as coral, fish, etc. nominate in aqueous rock Marine fossils found in layers of sedimentary rock in mountains, often thousands of feet above sea level. These marine fossils found at high elevation suggest past uplift of rock strata. change posture or settling of rock strataRock layers that have been moved.Horizontal Displacement (Faulting)Earth shifts side appearances along a diversify fault in the crustVertical Displacement (Faulting)Portion of Earths grow is either uplifted or subsides along a fault or crack. Benchmark eternal cement or brass marker in ground indicating a measured elevation.IsostasyCondition of balance or equilibrium in Earths crust.Since the upper mantle acts wish well a in truth dense fluid, the crustal casings float on top of it. Any change in one part of the crust is offset by a corresponding change in anformer(a) part of the crust. Example of I sostasyIf a piece of crust loses some of its material receivable to erosion, it becomes lighter and floats higher in the mantle. When the eroded material gets deposited, the crust is weighted down ca use that argona to sink lower into the mantle. some other isostatic example.The deposition of 2 miles thick ice on NY during a glacial ice maturate caused the ara to subside slightly. This forced other areas to rise higher in rejoinder to the settling under the ice. Later after the ice receded or melted, the region responded with gradual uplift causing minor unstable activity or quakes. fracture examples of crustal activity and explain where the zones of crustal activity are located. Areas of Crustal ActivityCrustal activities such as earthquakes and volcanoes occur for the most part in specific zones or regions of the Earth. These regions are usually along the borders of classics and oceans. These zones mark boundaries or edges of ample pieces of the Earths crust called cr ustal boundaries. ESRT p.5What is an earthquake? Explain the difference amongst an epicenter and a focus of an earthquake.Describe properties of the 3 types of earthquake drifts and tell the difference between a seismograph and a seismogram. I. EarthquakesSudden trembling or shiver of ground usually caused by movement along a break or a fault releasing built up stress When an earthquake occurs, seismic waves are created and move out in all directions from the focus or point of origin. The earthquakes focus or point of origin is usually deep below the Earths surface. The point on the Earths surface directly above the focus is called the epicenter. Describe properties of the 3 types of earthquake waves and tell the difference between a seismograph and aseismogram. II. Earthquake WavesSeismograph Instrument that detects and records seismic waves. Earthquakes generate several kinds of seismic waves that can be detected by a seismograph. 3 types of seismic waves are p, s, & l waves.L wavesLong wavesDo not pass through the Earth.Ripple along the surface of the EarthCreate the damage associated with earthquakesP wavesPrimary wavesAlso called compressional because they cause the material through which they pass to vibrate back and forth (compress) in the same direction as the wave is change of location. Called immemorial because they move quickly through the Earth with a greater velocity than secondary waves and therefore are the first waves to reach a distant location. S wavesSecondary wavesAlso called shear waves because they cause the material through which they pass to vibrate at right angles (up & down) to the direction in which the wave is expeditioning III. Velocities of WavesWhen traveling in the same material, primary waves travel at a greater velocity than secondary waves. So a seismograph will read the primary waves forward the secondary waves arrive. A single seismogram showing the arrival eons of p & s waves whitethorn be used to determine the dis tance to the earthquake and its time of origin. The greater the difference in arrival propagation of the primary and secondary waves, the greater the distance to the earthquake epicenter. Finding the Distance to an Earthquakes epicentreTo suffer out how far an epicenter was out from a location, a seismograph reading or seismogram is necessary that shows the arrival of both p and s waves. find the Exact Location of an Earthquakes Epicenter Epicenter location is found by the comparison of differences in travel time of p &s seismic waves. Knowing the separation time between arrival of both p & s waves gives the distance to the point on the Earths surface directly above the earthquake called the epicenter. Since simply the distance to epicenter and not direction is known, a circle is drawn with the radius equal to the distance. The epicenter is on the circle.To find the actual location of the epicenter you must find the distance from 3 different seismograph post. Why not 2? Draw 3 circles somewhat the 3 seismograph stations and where they intersect is the earthquakes epicenter. The earthquake occurred at a point somewhere below the epicenter and that internal point is called the focus. Scientists deficient to improve accuracy of finding the true epicenter will find the distance from more than 3 seismograph stations. canvass and contrast the 2 scales for determining the medium of an earthquake. a) The Modified Mercalli ScaleBased upon the damage inflicted by an earthquake.This intensity scale ranges from I to XII with I being felt by few stack to XII resulting in total devastation. Modified Mercalli Scale ContinuedAlthough this scale is still used, it is not very precise. Why? Damage inflicted by earthquakes depends on numerous factors besides the strength of the earthquake such as location, type of land, building design & structure, etc. b) The Richter ScaleA order scale used to describe the amount of naught released by an earthquake. Richter scale o rder of magnitudes range from 0 to 9.Each number step up the scale indicates a release of 32 times more energy than the previous step. Earthquakes that are less than 2.5 are not usually felt by people. Approximately 20 major earthquakes in the magnitude 7.0-7.9 occur every year and each 5-10 years an earthquake of 8.0 or more will devastate a portion of Earth. Give examples of dangers to humans from volcanic and earthquake activity. Dangers to Humans from Earthquakes and VolcanoesTell at least 4 of these hazards.Fires (Ruptured gas or power lines)Collapsing buildings/Falling DebrisBroken bridges and lanesTsunamis (Seismic ocean Waves)Lava menstruums melt and burnVolcanic ash & poisonous gases make it difficult to breathe Large submarine (under water) earthquakes or those that occur along a coastline whitethorn result in tsunamis or seismic sea waves. Describe differences between p and s wave transmission through the Earth and how it creates a hind end zone. VII. Transmission of E arthquake WavesThe velocity of an earthquake wave varies according to density of the material through which it is traveling. The greater the density of the material, the greater the velocity. As seismic waves travel through materials of different densities, the velocity of the seismic waves will change. This change in velocity of the wave causes the wave to be bent or refracted. Since the density of the Earth gradually increases with depth, seismic waves tend to increase in their velocity and continually refract (bend) as they travel down into the Earth. Difference in P and S Wave TransmissionCompressional or p waves are transmitted through all phases of matter solid, liquid or gas. However, shear or s waves are only transmitted through solids. This difference provides valuable information for scientists about the composition and interior structure of the Earth. S waves that penetrate the Earth to the depth of the outermost core disappear. Since these waves are not transmitted by t he outer core, the material of the outer core is assumed to be liquid. Earthquakes generate p & s waves that move out from the earthquake through the Earth in all directions. Seismographs that are located within 102 degrees from the epicenter record both p & s waves. Those seismograph stations that are farther away than 102o do not record any s waves because they are not transmitted through the core. A band that runs or so 102o to 143o away from the epicenter records neither p nor s waves. Describe a model of the Earths crust and interior. Describe characteristics of both the crust and interior. Crust & Interior PropertiesThere are 4 major Earth zones, three solid ones and one liquid. The 3 solid zones are the crust, mantle and inner core.The only liquid zone is the outer core.See ESRT p.10Crustal ThicknessThe crust of the Earth compared to other zones is relatively thin, only a few kilometers in average depth. The average thickness of the Continental crust is greater than the aver age thickness of the oceanic crust. Crustal CompositionThe continental crust is composed mainly of felsic perfervid rock like granite that is low in density. The oceanic crust is composed mainly of mafic eruptive rock like basalt that is high in density. Interior StructureCrust sits on top of mantle.Mantle accounts for the greatest part of the volume of the Earth. The crust-mantle boundary is called the Mohorovicic Discontinuity or the Moho. Below the mantle is the liquid outer core and the solid inner core. Interior CompositionEvidence from the behavior of seismic waves and metallic meteorites suggests that the inner portion of the Earth is a high density combination of the metallic elements iron (Fe) and nickel (Ni). Characteristics of Earths InteriorThe density, temperature and bosom of the Earths interior increases with depth. (ESRT p.10). The density ranges from 2.7g/cm3 for the continental crust and 3.0g/cm3 for the oceanic crust to 12.7 g/cm3-13.0g/cm3 for the inner core. Compare theories of continental drift and plate tectonics. Give evidence that support the idea that continents have moved. I. Plate Tectonics TheoryTheory that Earths lithosphere is do of a number of solid plates that move in relation to each other. ESRT p.5Continental DriftTheory that continents are now, as well as in the past, shifting positions. Wegener noted that the present continents appear to fit together as fragments of an originally larger landmass, much the same way the pieces of a scroll saw puzzle fit together. This is especially true if the edges of the continental shelves are used as the boundaries. However, over the years new evidence has been collected that indicates that approximately cc million years ago, the major continents were connected and since that time the continents have been moving generally apart. The following diagrams show the Inferred Positions of the Continents over the last 458 million years. Label the geologic Period for each diagram. Diagrams fo und in ESRT on page 9. Evidence to Support Idea that Continents Have MovedMany rock layers and fossils can be correlated across ocean basins. Rock types along with mineral composition and the fossils found in those rocks match up. A good example of this are rocks and fossils found on the east coast of South America match those found along the west coastline of Africa. Diamonds found in eastern Brazil are very similar to those found in western Africa. More Evidence for Continental MovementSome mountain chains appear to be continuous from continent to continent. Example Appalachians and CaledonianMore Evidence for Continental MovementRock and fossil evidence indicates ancient climates much different from those of today. Examples glacial deposits in tropical regions or coal deposits in Arctic More Evidence for Continental MovementRocks of the ocean basins are much younger than continental rocks. The most conclusive evidence comes from the ocean basins.Explain evidence for sea floor spr eading from both igneous ocean rocks and the reversal of magnetic polarity. Evidence to Suggest Sea radix SpreadingThere is much evidence to indicate that the ocean floors are spreading out from the mid-ocean ridges. The both major pieces of evidence are related to the age of igneous ocean materials and the reversal of magnetic polarity. a) Igneous sea RocksThe ocean crust is made up mainly of basalt that is formed when magma (molten rock) rises, cools, solidifies and crystallizes into igneous rocks of the mid-ocean ridges. Evidence shows that igneous rocks along the center of the mid-ocean ridge is younger (more recently formed) than the igneous rock found farther from the mid-ocean ridge. The age of igneous rock has been accurately determined using radioactive dating techniques. This suggests that as new ocean crust is generated at mid-ocean ridges, the ocean floor widens. Reversal of Magnetic PolarityThe strips of basaltic rock that inhabit parallel to the mid-ocean ridge sho w matched patterns of magnetic reversals. Check out this animation Over thousands of years, the magnetic poles of Earth reverse their polarities. The magnetic north pole changes to the magnetic south pole and vice versa. When the basaltic magma flows up in the middle of the ridge and begins to cool, crystals of magnetic minerals align themselves with the Earths magnetic field. This alignment of minerals in the rock leaves a recording of magnetic polarity for the Earth at the time of rock formation. When the Earths magnetic field is reversed, the new igneous rocks formed during the reversed polarity period have their minerals aligned in an opposite direction from the previously formed rocks. These changes in magnetic orientation are found in rock on both sides of the mid-ocean ridge, indicating that the development of the ocean floor is form the center of the mid-ocean ridges outward. Describe the 3 types of plate motion. Identify plate boundaries. Lithospheric Plates and Plate Bound ariesThree kinds of plate motion are associated with plate boundaries convergent, divergent and transform. a) Convergent Plate BoundariesConvergent Plate Boundaries- plates collide with each other Ocean Plate Meets Continental PlateIf an oceanic plate collides with a continental plate, the denser ocean plate made of basalt dives down (subducts) into the mantle forming a subduction zone with an ocean trench formed at the surface. At the subduction zone, old crust is consumed by the mantle to create more molten material. The overriding continental plate made of granite forms mountains. An example isthe Andes of South America. Ocean Plate Meets Ocean PlateIf two oceanic plates converge, the older, denser plate will subduct also forming a trench on the surface along with a chain of islands called an island arc. An example of this convergent subduction zone is the Northern and Western boundaries of the Pacific Ocean. Continental Plate Meets Continental PlateIf a continental plate collide s with another continental plate, the edge of both plates are crumpled up forming folded mountains. An example of this type of convergent boundary is the Himalayas of India. b) diverging Plate BoundariesDivergent Plate Boundaries- plates move apartA divergent boundary allows heat and magma to flow up from below forming parallel ridges made of new crustal material. An example of a divergent plate boundary like this is any mid-ocean ridge. c) Transform Plate BoundaryTransform Plate Boundary- plates grind slowly past each other At this type of boundary, crust is neither formed nor consumed. An example is San Andreas Fault in California.Shallow focus earthquakes are very common at transform boundaries. Plate Tectonic Map (ESRT p.5)Although plate motion is only a few centimeters a year, the interactions of the boundaries result in earthquakes, volcanoes and mountain building on a grand scale showing that the Earth is a dynamic system. Explain how mantle convection cells are opinion to b e the method for moving crustal plates. Mantle Convection CellsAlthough forces cost within the Earth that are powerful ample to move the lithospheric plates, the scientific community is not in total agreement on the specific apparatus (method) involved. Convection cell- menses of heated material that is moving due to density differences Evidence suggests that convection cells exist within a part of the mantle called the asthenosphere because of the occurrence of heat flow highs in areas ofmountain building and heat flow lows in areas of shallow subsiding basins. These convection cells may be part of the driving force which causes continents to move. What are impetuous spots? How are they formed?Hot SpotsHot Spots- places on Earths surface with unusually high heat flow most hot spots occur along active plate margins but some are found within the plates. Hot spots are thought to be caused by magma rising up from the mantle producing sites of active volcanism. Wow That was Dynamic Prepare for Chapter TestGood Luck* EartHquakes* Sub-topics* How strong is an earthquake?Do you live near an active fault?Earthquake and tsunamiWhat is inside the earth?* What is an Earthquake?* An earthquake is a shaking of the ground caused by the sudden gap and movement of large sections (tectonic plates) of the earths rocky outermost crust. The edges of the tectonic plates are marked by faults (or fractures). Most earthquakes occur along the fault lines when the plates playground slide past each other or collide against each other. * The shifting masses send out shock waves that may be powerful enough to alter the surface of the Earth, thrusting up cliffs and opening great cracks in the ground and cause great damage collapse of buildings and other man-made structures, mortified power and gas lines (and the consequent fire), landslides, snow avalanches, tsunamis (giant sea waves) and volcanic eruptions. * How strong is an Earthquake* Earthquakes are measured in two different ways1.) Magnitude2.)Intensity* Earthquake magnitude* Earthquake magnitude is a measure of the energy released by an earthquake, or its size. Because earthquakes vary a lot in size, earthquake magnitude scales are logarithmic. For a one-step increase in magnitude the amount of energy released increases about 32 times. So a magnitude 7 earthquake is 32 times bigger than a magnitude 6 earthquake, and a magnitude 8 earthquake is 1000 bigger. * Earthquake intensity* Earthquake intensity describes how much ground shaking occurred, or how strong an earthquake was, at a particular location. Earthquake waves wishy-washyen as they travel away from the earthquake source, so an earthquake generally feels less strong the further away from the source you are. * Earthquake intensity* The intensity of an earthquake is determined by observing the effects of the earthquake in different places. Houses, buildings, and other structures are inspected. People are interviewed about what they saw (the cabi net fell over), how they felt (I was frightened), or what they did (I ran out of the house). * The Modified Mercalli (MM) intensity scale* MM 1Not felt.* MM 2Felt by peeple at rest on upper floors of buildings. * MM 3Felt indoors, like a delicate truck passing hanging objects swing slightly. * MM 4Felt indoors by many, like a heavy truck passing hanging objects swing, windows rattle. * MM 5Felt outdoors, sleepers awakened, handsome objects and pictures move. * MM 6Felt by all, crockery breaks, furniture moves, weak plaster cracks. * The Modified Mercalli (MM) intensity scale* MM 7Difficult to stand, noticed by car drivers, furniture breaks, weak chimneys break at roof line, plaster, loose bricks and tiles fall. * MM 8Driving is difficult, ordinary masonry is damaged, chimneys and towers fall, some liquefaction. * MM 9General panic, poor masonry destroyed, ordinary masonry and foundations damaged, liquefaction and landslides. * MM 10Most masonry structures destroyed. Some well-buil t wooden structuresand bridges destroyed. Dams and embankments damaged, large landslides. * MM 11Few buildings left standing.* MM 12Damage nearly total.* FAULTS* What is a fault?* A fault is a break in the rocks that make up the Earths crust, along which rocks on either side have moved past each other. * The direction of movement along the fault plane determines the fault type. * 3 Major Faults* Normal* Reverse* Strike-slip* Do You Live Near an Active Fault?* An active fault is one that has moved in the past and is judge to move again. Put in another way, an active fault has generated earthquakes before and is capable of causing more in the future. * Scientists use different ways to find out if a fault is active. One is by checking the countrys historical records. Historians always write about destructive events such as earthquakes. * Another is by studying the vibrations, past and present, that come from faults. Still another way is by observing the surroundings. For example, a fa ult may cross a road and because of that, the road is displaced. * Do You Live Near an Active Fault?* Or a fault may cut across a stream and the stream channel is then shifted. Or a fault may slice through mountains and form cliffs. This is not to say that anyone can spot an active fault. Scientists pauperisation a lot of training to do that. * But along some faults, the effects may be dramatic. Suppose a house was built on a fault. As the ground shifts little by little, parts of the house will be affected. The floor will crack, doors will not close, and the roof may start to leak. * Obviously, it is important to know the location of active faults. As far as possible, no important structures should be built near or on them. Tsunami* What is a tsunami?* A tsunami is a series of waves usually caused by an undersea earthquake that displaces the ocean floor. But a tsunami is not really a wave that moves up and down its actually the ocean moving sideways as a massivesurge or a wall of w ater. Its also knownas a tidal wave. The Japanese word tsunami means harbor wave.A tsunami can generate waves for 12 to 24 hours. And the first wave is not always Japan, 2011 The capital of Massachusetts Globe the biggest A tsunami travels across the open ocean at over 500mph, the speed of a jet airplane. As it reaches shallower water and approaches shore, it slows down but grows in height. A tsunami can happen at anytime of day or year. How do earthquakes generate tsunamis?* Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the lie water. Tectonic earthquakes are a particular kind of earthquake that are associated with the earths crustal deformation when these earthquakes occur beneath the sea, the water above the distorted area is displaced from its equilibrium position. Waves are formed as the displaced water mass, which acts under the influence of gravity, attempts to regain its equilibrium. When large areas of the sea floor elevate or subs ide, a tsunami can be created. * What is a Tsunami Earthquake* A tsunami earthquake is an earthquake that triggers a tsunami of a magnitude that is very much larger than the magnitude of the earthquake as measured by shorter-period seismic waves. Such events are a result of relatively slow rupture velocities. They are particularly dangerous as a large tsunami may arrive at a neighbouring coast with little or no warning. a tsunami earthquake is that the release of seismic energy occurs at long periods (low frequencies) relative to typical tsunamigenic earthquakes. Earthquakes of this type do not generally show the peaks of seismic wave activity associated with ordinary events. A tsunami earthquake can be defined as an undersea earthquake. * What is inside the Earth?* Earths Layers* CrustThe crust is the first layer of the earth. It is split up intotwo parts the continentalcrust, and the oceanic crust.* MantleThe mantle is the second layer of the earth. It is split up into two differe nt parts, the lithosphere (which is the top part) and the asthenosphere (which is the bottom part). * Earths Layers* Outer coreThe outer core is a liquid made up of iron and nickel. The depth of the outer core is 2, 890. This is one of thethree layers that is putting pressure on the inner core. * Inner coreThe Inner crust is the second thinnest layer. The inner core is hotter than the surface of the sun. The inner core is made out of iron and nickel. It is 5159 to 6378 km thick. * Earths Layers* The Earth is formed of three concentric layers the core, the mantle and the crust these are separated by transition zones called discontinuities. * Mohorovicic discontinuity* Gutenberg discontinuity* How the seismic waves travel* The shaking starts from the focus and spreads out. You can get an idea of how this happens by throwing a pebble into a pond. See the ripples that move out in circles? The vibrations from the focus are something like that. * The vibrations are more properly called se ismic waves. As seismic waves travel through the body of the Earth, they behave in different ways, depending on what they encounter along way