Transcript of Earth Science Performance Task
Earth Science Performance Task Lima, Peru By Brooke Fida Lima, Peru is situated on the Nazca Plate and South American Plate Boundary. This convergent boundary forms the Andes Mountains. The Andes Mountains are one of the longest mountain ranges on Earth. It is over 7,000 km (4,400 miles). These mountains go through Argentina, Bolivia, Chile, Columbia, Ecuader, Peru, and Venezuala. It's peaks are over 6,000 meters (19,685 feet). Anconcagua is the highest peak in the Andes at 6,962 meters (22,841 feet). Many of the peaks happen to be active volcanoes. The Andes form a massive barrier between the eastern Pacific Ocean and the rest of the continent of South America. The forces of the tectonic plates are responsible for this mountain range. This is an example of the plate boundary. At a rate of about 60mm per year, the South American plate is moving towards the Pacific Ocean over the Nazca Plate. This puts a strain on Earth's crust. These pressures are periodically released through earthquakes. This forms a convergent boundary. At a convergent boundary, mountains or a subduction zone can form. A mountain is a large, natural, elevation of the Earth's surface rising abruptly from the surrounding level. At this plate boundary, there happens to be a subduction zone. The Nazca Plate is going under the South American Plate. Plate Tectonics Plate tectonics is the theory that the Earth’s outer layer is made up of plates, which moved throughout Earth’s history. The lithosphere is broken into separate sections of crust, some as large as whole continents. These sections form plates. The plates are in a slow, constant motion. All of these plates used to be together in one super-continent called Pangaea. It is predicted that in the future they will come back together and form Pangaea Ultima. Now, you're probably wondering; why do these plates move? They move because of something called convection currents. Convection currents is when heat from the mantle rises since it's hot, cools, then drops because it's more dense. It then gets hot again because it's closer to the mantle, so it rises and the whole process starts all over again. This process forms convection currents that have a circular motion. Convection currents can move in different directions, so it creates different types of movement, which leads to different types of plate boundaries. A plate boundary is where two or more plates meet. Layers of the Earth Basic Layers of the Earth Sub Layers and Layers of the Earth The crust is the outer most layer of the Earth. The lithosphere is made up of the crust and upper part of the mantle. The mantle is the middle layer of the Earth. The asthenosphere is a thick, liquid- like layer. The lithosphere floats and moves on this layer. The mesosphere is the strong, lower part of the mantle. It extends down to the outer core. The core is the inner layer of the Earth, The outer core is a truly liquid layer that is thought to flow and give the Earth's magnetic field. The inner core is the solid, dense center of the Earth made from iron and nickel. What causes volcanoes? Volcanoes are found at plate boundaries where they are either diverging or converging. A divergent boundary is a place where two plates move away from each other. A convergent boundary is a place where two plates move toward each other. Since volcanoes are a fissure in the Earth's crust through which molten lava and gases erupt, they aren't found at transform boundaries. A transform boundary is a plate boundary where two plates move past each other in opposite directions. At a convergent boundary, a subduction zone might form. A subduction zone is the process by which ocean floor sinks into a deep ocean trench and back into the mantle. When the denser oceanic crust sinks down into the mantle, there is a huge amount of pressure. This pressure forces it's way up and forms a chain of volcanoes or islands. An island is a piece of land surrounded by water. At a divergent boundary, a mid- ocean ridge could form. A mid-ocean ridge is a place where sea-floor spreading takes place. Sea- floor spreading is when new oceanic lithosphere forms as magma rises toward the surface and solidifies. As this happens, magma comes up and forms volcanoes. Since the tectonic plates are still colliding to this very day, it causes earthquakes and volcanic eruptions in the region. Unfortunately, Lima, Peru is located near the water so there is a high risk of tsunamis. For example, in 1746 the earthquake took 5,000 people. Many people died when a tsunami swept the coast. A tsunami is a long, high sea wave caused by an earthquake or other disturbance. What causes earthquakes? Earthquakes can be found at a transform, divergent, or convergent boundary. The most powerful earthquakes are at transform or convergent boundaries. An earthquake is a sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the Earth's crust or volcanic action. Since at convergent and transform boundaries the plates are touching/colliding, they can cause an earthquake because of rough movements or friction. Friction is the resistance that one surface or object encounters when moving over another. This often occurs at transform boundaries. At a divergent boundary, an earthquake can be caused because of a rift valley. A rift valley is a large elongated depression with steep walls formed by the downward displacement of a block of the Earth's surface between nearly parallel faults or fault systems. After a rift valley is formed, the movements can trigger an earthquake. Earthquakes can form faults and occur near them. A fault is a break or crack in the Earth’s crust where rocks have slipped past each other. Why do volcanoes and earthquakes occur at the boundary types of each of the selected cities? Lima, Peru Reykjavik, Iceland San Francisco, California At Lima, Peru, there is a convergent boundary. Volcanoes form here because when two plates push together, they can either form a mountain or a subduction zone. A mountain can turn into a volcano if it releases gases and if magma pushes out of it and erupts. When a subduction zone forms, the pressure causes a chain of volcanoes or islands to form. Earthquakes can form at Lima, Peru because when the plates push together, they shake the ground and cause movements which trigger earthquakes. At Reykjavik, Iceland, it's a divergent boundary. At a divergent boundary, gaps will form when sea floor spreads. This makes the crust weak so magma can easily come up and erupt, making a volcano. In fact, the entire island (long ago) was formed by lava cooling and turning into a rock. At San Francisco, California, it's a transform boundary. A transform boundary can form earthquakes because the plates are making a lot of rough movement. The plates slide past each other, forming many major earthquakes. Reykjavik, Iceland Reykjavik, Iceland is situated on the North American and Eurasian Plate Boundary. This boundary is divergent. There were two large earthquakes in the South Island seismic zone on June 17 and 21 in the year 2000. Luckily, there were no major earthquakes in Reykjavik, but there were at least four in the South part of Iceland (which is pretty close the Reykjavik). Reykjavik is sitting smack dab at a mid- ocean ridge, where volcanoes are formed. Iceland is one of the most eruptive places on Earth with over 200 volcanoes. Plates at Iceland Reykjavik's plates move slowly apart at a rate of 1 inch per year. Fissures will periodically form in the crust over time. These gaps allow molten rock from under ground to surface as lava. This explains why Reykjavik is known for its major volcanoes. Iceland happens to be one of the few places in the world where a divergent boundary occurs above sea level. Over 1,000 years ago, long after continents had formed, lava from volcanic eruptions along the mid- ocean ridge cooled as basalt. Basalt is a dark, fine-grained volcanic rock that sometimes displays a columnar structure. This created all of Iceland's present day land surface. Volcanic Eruptions Documented history of Iceland's volcanic eruptions began in 874 A.D., when the Vikings first settled on the land. Since that time, the island has had about 125 volcanic eruptions. Iceland is small, so that is more than any other comparably sized region in the world! Faults There are three different types of faults:Full transcript
A strike-slip fault is a type of fault where rocks on either side move past each other sideways caused by a shear force (sliding).
A normal fault is an inclined fault in which the hanging wall appears to have slipped downward relative to the foot wall.
A reverse fault is a geological fault in which the upper side appears to have been pushed upward by compression. History of Volcanoes Iceland is the largest site of lava flow in recorded global history. In 1783, an eruption at a mountain called Laki tore a chain of giant craters in the Earth. It released 219 cubic miles of lava, which took up 218 square miles of land. Toxic particles in the air were reported as far away as Syria. It killed 1/4 of the islands residents. In Iceland, there is an average of one eruption every five years. The majority of these blasts have occurred far from human settlements. Some of these eruptions have led to famine, destroyed homes, and generally wrecked other things on human settlements. San Francisco, California San Francisco, California lies between the Pacific Plate and North American Plate. These two plates are sliding past each other, which makes a transform boundary. In about 10 million years, Los Angelos and San Francisco will be side by side. The Pacific Plate (which is on the West) is moving Northwestward relative to the North American Plate (which is on the East). This causes earthquakes along the fault. San Andreas Fault The fault that San Francisco is on is called the San Andreas Fault. This fault is a major earthquake spot. The San Andreas Fault System is more than 800 miles long and extends to depths of at least 10 miles within the Earth. The fault is a complex zone of crushed and broken rock from a few hundred feet to a mile wide. There are many smaller faults that branch and join the fault zone. This forms a continuous narrow break in Earth's crust that extends from Northern California Southward to Cajon Pass near San Bernardino. The blocks on opposite sides of the fault move horizontally. For example, if a person stood on one side of the fault and looked across from it, the block on the opposite side would appear to the right. Geologists refer to this as right-lateral strike-slip. Why Earthquakes? California has so many earthquakes due to strain building up for over 100 years or more. The strain is eventually released which produces great earthquakes. There are 1,000's of small earthquakes in California each year. Two of the largest earthquakes were in 1857 and 1906. Both of these earthquakes were about the same magnitude. Magnitude is the "size" of an earthquake, expressing the amount of energy released in the form of elastic waves as measured by a seismograph, on a scale such as Richter's. In 1857, there was as much as 29 feet of movement. In 1906, the earthquake took about 700 lives and caused millions of dollars worth of damage. This earthquake was even felt in central Nevada and Oregon! It is estimated that an earthquake with a 5-6 magnitude will occur before the end of the century. What city would I choose to live in/which city is the safest? I would choose to live in Reykjavik, Iceland. I would want to because I think it is much safer than San Francisco, California or Lima, Peru, which mostly have earthquakes. Iceland has a lot of volcanoes, but I personally don't think that volcanoes are that dangerous. To me, earthquakes can cause so much more damage and can kill way more people. Volcanoes Earthquakes Earthquakes are very dangerous and unpredicted. You could never know when one will occur. Also, once one starts, you can't leave the area because it's too dangerous. You never know how long one will go on or how dangerous it will be.The only thing that scientists can predict is around the area they take place (plate boundaries/faults). All three of the cities are near plate boundaries, but earthquakes are mostly near San Francisco and Lima, since they're a transform and convergent boundary. Not a lot of earthquakes are near Reykjavik because it's on a divergent boundary. Volcanoes are dangerous, but not as dangerous as earthquakes. Scientists can tell when a volcano will erupt by studying it and the area. As long as you are a safe distance, humans shouldn't be effected by volcanoes. Most civilizations are far from the nearest volcano, like Iceland. The only time that people are even close to a volcano is when they are tourists (which is safe because there are experienced scientists nearby), or when they're a scientist that is studying it. Also, if a volcano is going to erupt, the area would be evacuated days before the eruption takes place and everyone would be safe and far away to get hurt. As you can see, earthquakes are really dangerous but volcanoes aren't that bad. Reykjavik, Iceland has mostly volcanoes but Lima, Peru and San Francisco, California have really bad earthquakes. That is why I would rather live in Reykjavik, Iceland. Works Cited
Earthquakes in Lima and Peru. Lima Easy, 2013. Web. 5 Apr. 2013. <http://www.limaeasy.com/earthquakes-in-peru/earthquakes-info>.
The Andes Mountains. Windows to the Universe, 2012. Web. 29 Apr. 2013. <http://www.windows2universe.org/geography/andes.html>.
Iceland Earthquake Information. USGS, 2012. Web. 29 Apr. 2013. <http://earthquake.usgs.gov/earthquakes/world/index.php?regionID=58>.
Plate Tectonics. ETE Team, 2005. Web. 29 Apr. 2013. <http://www.cotf.edu/ete/modules/msese/earthsysflr/plates1.html>.
Volcanoes, Volcanoes, Volcanoes. Mike Matz, 2001. Web. 29 Apr. 2013. <http://www.exploratorium.edu/theworld/iceland/volcanoes.html>. A foot wall is the part of the fault where you can walk up. A hanging wall is the part of the fault where you can't walk up, only hang from it.