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Volcano Presentation

Transcript: Earth Science Project By Rafael Martinez-Salas Describing the Layers of the Earth The inner core is a solid section of the Earth and is unattached to the mantle, being suspended by the molten outer core. This solidified state is the result of a very intense pressure-freezing process that occurs in most liquids when temperature decreases or pressure increases. The outer core of Earth is a scorching hot, electrically conductive liquid in which convection takes place. This inner layer in mutual combination with the rotational motion of the Earth creates a dynamo effect where a force field of electrical currents is generated. This field is also known as Earth's magnetic field, which is responsible for the functioning of mechanical and biological compasses. This field also causes a subtle jerking motion in the Earth's daily rotation. In terms of the physical aspects of the outer core, the layer is dense, but not as dense as pure molten iron, evidencing the presence of multiple impurities having a lighter chemical makeup. According to scientists, about 10% of this layer is composed of sulfur and/or oxygen due to the fact that these two elements are abundant in the cosmos and dissolve readily in molten iron. The outer core is in the range of 200 to 300 kilometers (125 to 188 miles) thick and represents about 4% of the mantle-crust mass. This layer is sometimes identified as part of the lower mantle due to its geographical nature. However, studies on seismic discontinuities suggest that this "D" layer might differ chemically from the lower mantle lying above it. Looking at the lower mantle, its chemical composition includes silicon, magnesium, and oxygen. Most likely, it probably also contains some iron, calcium, and aluminum. This layer is comprised of 72.9% of the mantle-crust mass, making the Earth abundant in the chemical elements of silicon, magnesium and oxygen, the layer's primary components. The next layer, the Transition region comprises 7.5% of Earth's mass with a depth of 250-406 miles (400-650 kilometers). This layer is also known as the mesosphere and is 11.1% of the mantle-crust. It is made of mainly basaltic magmas with amounts of calcium, aluminum and garnet (an aluminum-bearing silicate mineral). The layer becomes dense when the garnet mineral cools but is buoyant and light when subject to heat due to the low melting points. The outer most layer, the crust, is categorized into two parts, the Oceanic crust and the continental crust. The Oceanic crust is the smallest part of Earth, only 0.099% of its mass and reaching a small depth of 0-6 miles (0-10 kilometers). In the beginning of time, it was possible that this area did not exist for through frequent volcanic activity does only the crust form. Evidence of this is marked by the oceanic ridge system, which is a 25,000 mile (40,000-kilometer) array of many volcanoes which creates layer after layer of new crust at the rate of 17 km3 per year. The ocean floor is covered in basalt originating from volcanic activity and as a matter of fact, Iceland and Hawaii are two island systems that emerged from the accumulated basalt. Continental crust: The second smallest area of the Earth is the Continental crust, making up only 0.374% of the Earth's mass and extending a short depth of 0 - 31 miles (0-50 kilometers). Looking at the percent by composition, the continental crust makes up only 0.554% of the mantle-crust mass. The layer is composed primarily of crystalline rocks made of low-density buoyant minerals dominated mostly by quartz (SiO2 aka Silica) and fieldspars (metal-poor silicates). This is the outer part of the Earth composed essentially of crystalline rocks. The continental crust and the oceanic crust are also referred to as the lithosphere because of the cool and rocky conditions that exist in its chemical composition. Pieces of Evidence that Support the Continental Drift Theory Magma rises and spreads the sea floor. At the boundary between the plates, the ocean floor sinks, but at the same time is pushing against the continents. At the plates move, most of the geological structures and events we are familiar with occur, including earthquakes and volcanoes. Plate tectonics a major theory explaining the dynamics of our planet Earth and our understanding would not have been the same without it. In the 1960's a gentleman by the name of Harry Hess proposed that not only were the continents moving, but the sea floor was also moving. Motion of the sea floor in a conveyor belt fashion explains the phenomena of the youngest rocks being found only at the mid-ocean ridges, and the rocks get progressively older as you move away from the ridge. If the sea floor is spreading, then clearly the continents could diverge from one another. The rock of the sea floor also exhibited magnetic properties. Not only did the magnetism of these rocks change over time, they completely reversed which supported the motion of the magnetic poles. Hess's explanation of the motion of

Volcano Presentation

Transcript: Volcano Presentation El Chichon Patzy Carmona Location: It is in northwestern Chiapas, Mexico. 17.360°N / 93.228°W It is a lava dome A steep-sided mass of viscous and commonly blocky lava extruded from a vent; typically has a rounded top and roughly circular outline History: The first erruption happened around 550, then in 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700 years BC El Chichon’s most famous eruption was in 1982. It lasted from March 28 to April 4, 1982. It generated pyroclastic surges and flows that dammed adjacent drainages including the Magdalena River. This created a 4 km long and 40 km wide lake that drained catastrophically and inundated the town of Ostuacan with a mixture of hot water and pyroclastic sediment. The eruption on April 3rd that let out pyroclastic surges and flows killed more than 2000 inhabitants. The eruption was unique due to the release of unusually large amounts of sulfur into the atmosphere. Three weeks after the eruption, the volcanic aerosol had circled the Earth and severely affected aircraft particularly in the northern hemisphere. Pyroclastic flows and surges destroyed nine villages south of the volcano. Cultural Significance: The eruptive history of El Chichón also offers clues in the investigation of the Maya civilization. Several researchers have considered the volcano as an important factor in the answer to some intriguing questions such as the extensive use of volcanic ash in Late Classic Maya ceramics or, of greater importance, the causes of the collapse of the Classic Maya civilization. Structure and Composition: Summit elevation is 3,773 ft The former summit of the volcano was constructed within a 1.6 x 2 km summit crater created about 220,000 years ago. The eruptions in 1982 created a new 1-km-wide, 300-m-deep crater that now contains an acidic crater lake. The magma erupted by El Chichon have a trachyandesitic composition with a similar mineral association of plagioclase, amphibole, augite, magnetite, sphene, pyrrothite, biotite, and apatite. Status: Even though it is famously known for the large eruption in 1982, it is not very large and not very active. The origin of El Chichón volcano has been related to the subduction of the Cocos plate beneath the North American plate at the Middle American Trench. This ongoing subduction process is occurring at an average convergence rate of 66 mm/yr in a northeast direction. The projected slab is dipping at an angle of 40° and has an approximate thickness of 39 km. This geometry sets El Chichón, which is at 400 km from the trench to about 300 km above the subducted slab under Chiapas. Properties: El Chichon is known for its felsic magma. The powerful 1982 explosive consisted of high-sulfur, anhydrite-bearing magma, and was accompanied by pyroclastic flows and surges that devastated an area extending about 8 km around the volcano. Works sited: Cain, F.C. (2009, June 5). El chichon volcano. Retrieved from Stanbrough, L.S. (2007, February 18). El chichon eruption - april 1982, mexico. Retrieved from Espíndola, J. M. E. (2000). Volcanic history of el chichón volcano (chiapas, mexico) during the holocene, and its impact on human activity. Retrieved from Type: Formation:

Volcano Presentation

Transcript: Calderas, Rifts, and The Ring Fire. Pictures There are 3 main types of volcanoes. A Cinder cone volcano, A Shield volcano and a Composite volcano. To go more in depth about these volcanoes let's start with the Cinder cone. Cinder cone volcanoes are usually explosive which shoot pyroclastic material which is a cloud of debris which is usually made out of ash, rocks and lapilli which is a small rock that shoots out of a volcano. Pyroclastic material is also what builds up this volcano. The next type of volcano is a Shield volcano. This is built up buy lava but the lava runs so far it's more lengthy than tall and usually has an enormous crater at the peak you also might get some pahoehoe which is smooth flowing lava. The third one is a Composite volcano and its called that because it's made up of volcanic ash and lava. Volcanoes are formed when less-dense mantle plumes which are found on hotspots. Hotspots are a place directly above a rising magma column, as mentioned previously, a mantle plume. That's how the magma gets to the volcano but the volcano is shaped by a Convergent boundary which is when two sections of the lithosphere plates are colliding. Those create enough pressure to build up a mountain which always has the potential to become a volcano. By: Jeremy Brodersen Ways we study volcanoes Let's start with calderas. Calderas are whena volcano has run out of magma in the magma chamber and it starts to sink into the ground. A famous caldera would be Mount Mazama which now has Wizard Island on it. Now to rifts. Rifts are deep cracks that form when tectonic plates separate. Rifts are especially common near shield volcanoes. Hawaii has lots of faults because it has lots of shield volcanoes. Now onto the ring of fire. The ring of fire is located in the Pacific ocean and the thing about that is that most of the volcanoes are on the borders with tectonic plates. How volcanoes are formed 4 ways we study volcanoes include measuring activity of the volcano such as earthquakes near/inside the volcano that are becoming more frequent. Another way we study volcanoes is by studying deformation. Example is Mt. Saint Helens' bulge. A third way we study volcanoes is by looking at what volcanoes are are spewing out such as increased levels of gas. The final way we study volcanoes is by studying gravity and magnetics. We could also tell this with the Mt Saint Helens because it's bulge you could tell was eventually going to collapse. Volcanic Presentation Types of Volcanoes and what comes out of them

Yellowstone Volcano Background

Transcript: Future basaltic eruptions could cover several square kilometers with lava up to tens of meters thick. Ash entering atmosphere and blowing down wind for many kilometres. Damage to structures by ash loading. secondary consequences include wildland fires, debris flows, and floods triggered by the displacement of surface drainages by lava. Approximatly 10x larger than mt st Helens. Is yellowstone as big a threat as reported? The site is very much still active: - 1000 to 3000 earthquakes a year. - Active ground deformation. - Over 10,000 thermal features. Impacts of future eruption: Recurrence: 3 Largest - Deposits of rhyolitic ash so hot that they welded into sheets of dense rock covering large areas, extending beyond the national park. - Also produced a rain of ash that spread over much of western and central North America and beyond. - No volcanic eruption for last 70,000. Abundant evidence that hot magma continues to exist beneath Yellowstone, but it is uncertain how much of it remains liquid, how well the liquid is interconnected, and thus how much remains eruptible. Unlikely but possible Evidence Yellowstone National Park Yellowstone Volcano Background Conclusion Past Eruptions: Articles: Against: The probability of another major caldera-forming Yellowstone eruption, in the absence of strong premonitory indications of major magmatic intrusion and degassing beneath a large area of the caldera, can be considered to be below the threshold of useful calculation. For: - Average recurrence time of an explosion large enough to produce a 100-m-diameter crater is probably about 200 years, but such an event could expel rocks and other hot debris more than 2 km from the explosion site - At least 26 hydrothermal explosions have been documented in the 126-year historic record of the national park - The average period between basaltic eruptions in the Yellowstone region since formation of the Yellowstone caldera has been about 16,000 years - Supervolcano - The Yellowstone Plateau was built by one of Earth's largest young volcanic systems - Has ejected lava and ash for more than 2 million years. - Formed of Basaltic and rhyolitic magma. Old Faithful Geyser

volcano presentation

Transcript: An eruption our project is about volcanoes. we well be discussing about the types of volcanoes and the ways they are made. we well also briefly talk about the effects they can have on us. what is a volcano A volcano is a mountain that opens downward to the molten layer of the earth. Pressure builds up and eruptions occur. Lava shoots through the hole . How do volcanoes form • Volcanoes are usually formed by the movement of the tectonic plates in earth. • The plates are rocks that float on molten • Mantle is the liquid layer of the earth. • The tectonic plates are always in very slow motion. Sometimes these plates can move towards each other. Most times they well move apart from each other. • When they move to each other one plate goes under while the other rises above it. • As the plate sinks it goes to the molten. It becomes so hot and the mantle comes to the surface through the cracks the plate left. • When it comes to the surface it makes lava. • The lava turns into volcano as it dries over time What are the types of volcanoes? There are three types of volcanoes. They have different features and shapes. The three types of volcanoes are the shield volcanoes, cinder cones volcanoes and composite volcanoes. shield volcano They are large volcanoes that are made of fluid lava flows. It is surrounded by slop hills in a circular shaped pattern that looks like a shield. Different stages of volcano volcanoes are categorized into three different stages. active volcano: it is a volcano that has recently erupted and could possibly erupt anytime. dormant volcano: a volcano that has not erupted in a long time, but their is a possibility that it could erupt again. extinct volcano: a volcano that hasn't erupted for thousands of years and their isn't a chance it will. what is a cinder cone volcano? The volcano forms when ash cinders and bombs pile up around the vent to form a circular or oval cone. composite volcanoes composite volcanoes are made of volcanic rocks. it is usually made of lava and ash debris.

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