Exam 2 Study Guide

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EAPS 106, Geosciences in the Cinema Exam 2 Study Guide Know the following: Unit 4 - Tsunamis 1. Why it is not sufficient to be a good swimmer to survive a tsunami. People are often crushed by debris when they are caught in tsunamis because of how powerful they are. 2. The process associated with subduction zone earthquakes that causes a tsunami to be generated. Elastic rebound of the overriding plate causes uplift of the seafloor, which causes a mountain of water to form that then falls away in both directions to generate tsunamis in both directions 3. The direction an island above a subducting plate moves between earthquakes. Between earthquakes, an island above a subducting plate sinks. During an earthquake, the island rises 4. The magnitude a subduction zone earthquake has to be to generate a large tsunami. In order to generate a large tsunami, an earthquake must be at least M9 5. That tsunami waves traveling through the deep ocean are influenced by seafloor topography. Tsunami waves are influenced by seafloor topography as they travel, which can influence how the wave spreads. This is because a subduction zone tsunami is initiated on the seafloor 6. That slip on an underwater strike-slip faults cannot cause a significant tsunami. Strike-slip faults will not cause a change in the height of the seafloor; thus they do not displace water and will not generate a tsunami 7. How tsunami waves differ from large wind-blown waves. Tsunami waves and wind-blown waves can have similar heights, but tsunami waves carry a much larger volume of water and have a longer wavelength (wind-blown waves are only on the surface, while tsunami waves go all the way to the seafloor) 8. What happens to a tsunami wave speed and height as it approaches the shore. As tsunami waves approach the shore, they slow down, causing the wavelength to decrease and the wave height to increase to 10s of feet (in deep water the waves rarely have heights over 1m) 9. What happens to the distance between tsunami wave crests as they approach the shore. As tsunami waves approach the shore, the wavelength of the waves decreases. 10. What “tsunami” translates to in Japanese. Tsunami is Japanese for harbor wave because fishermen out at sea would not be able to tell a tsunami was coming and then come home to a destroyed town 11. What happens to a boat in the middle of the ocean when a tsunami wave passes underneath. Boats in the middle of the ocean would rise less than 1m of a period of 10s of seconds if a tsunami wave passed underneath 12. When a wave moving toward shore typically breaks. A tsunami wave moving towards shore typically breaks when the height of the wave is roughly equal to the depth of the water 13. Why inlets (natural harbors) are particularly dangerous places when a tsunami hits. Inlets are dangerous because the incoming water becomes trapped and piles up, causing wave heights to increase even more 14. That an earthquake on the San Andreas Fault cannot cause a tsunami. The San Andreas Fault cannot create a tsunami because it is a strike-slip fault 15. That tsunami waves can be extremely deadly even many miles inland from the shore. This is true, tsunami waves can carry great amounts of debris, which is very dangerous 1
16. The approximate number of people killed by tsunamis in the past 1000 years. Several hundred thousand 17. That the 2011 Japan tsunami was not unprecedented in Japan’s history. Japan should have anticipated the 2011 tsunami because they have has 3 10+ meter tsunamis in the past 400 years 18. What a Japanese tsunami stone is. A stone that is placed where the tsunami waters reached, warning people not to build below them 19. How we know that the northwest coast of the U.S. has experienced large tsunamis. Buried sand deposits along the coast of the Pacific Northwest 20. The time it takes from earthquake to a tsunami reaching the nearest coastline. After a significant earthquake, the tsunami will hit roughly 20-40 minutes later 21. Why sea level drops dramatically before a tsunami arrives. The tide appears to go out when the trough of the tsunami wave arrives before the create, meaning that the tsunami is collect enough sea water to travel through 22. Why it is dangerous to return to the beach after a tsunami wave first arrives. It is dangerous to return to the shore after the first tsunami arrives before than be anywhere from 3-10 waves that occur over many hours 23. What a tsunami seawall is. A concrete wall on the beach that protects the land from tsunami water going too far inland 24. The length of time it takes a tsunami wave to cross the Pacific Ocean. It takes about 1 day for a tsunami wave to cross the Pacific Ocean 25. Why there was a high death toll in the Indonesian tsunami of 2004 around the Indian Ocean. There wasn’t enough education about tsunamis, there was no early warning detection system for tsunamis or any way to warn the public 26. How the DART tsunami early warning system works. A pressure sensor on the seafloor measures the water pressure which is then sent to a buoy and then used to determine if there is risk of a tsunami. Can send out tsunami warnings as quickly as 15 minutes after an earthquake with size and path estimates 27. The process that can cause the largest tsunamis. Asteroid impacts have the potential to create the largest tsunamis, but they are rare. 28. The process that caused the largest tsunami run-up recorded in the past 100 years. A landslide in Litya Bay in Alaska in 1958 caused the largest tsunami run up in the past 100 years 29. The time it takes for a tsunami to travel from the Åkerneset cliffs to Geiranger. A tsunami from the Akernest cliffs would take only 10 minutes to reach Geiranger 30. What generally causes tsunamis generated at the Hawaiian Islands. Underwater landslides currently pose the largest threat for tsunamis to be generated in Hawaii 31. The mostly likely cause of a tsunami to hit the U.S. east coast. The east coast of the US is vulnerable to tsunamis that are generated by underwater landslides initiated from the Canary Islands 32. The cause of the tsunami that killed 36,000 people in Indonesia in 1883. The volcanic eruption of Krakatoa caused a tsunami that killed 36,000 people in Indonesia 33. The vulnerabilities of Florida if a 10-km-diameter asteroid hit the Gulf of Mexico. If a 10 km diameter asteroid hit the Gulf of Mexico, Florida would be completely overrun by water Unit 5 - Volcanoes 2
34. The difference between magma and lava. Magma is below the Earth’s surface, lava is above the Earth’s surface, but they are both melted 35. That there is no ocean of magma beneath the lithosphere. There is no ocean o magma beneath the lithosphere. Most of the mantle is below its melting point and magma only occurs in specific places 36. The temperature of the mantle compared to its melting temperature. Most of the mantle is cooler than it melting point except for a small percentage of magma 37. The processes which will promote the melting of hot rocks. Increase temperature, decrease pressure (depressurized melting causes the melting temperature of rocks to decrease), hydration-induced melting ( adding water causes long silica chains to be broken, reducing the melting temperature of rocks) 38. The type of volcanism found far from plate boundaries. Hot spots are typically found far away from plate boundaries 39. The process that causes hot rocks to melt at subduction zones. Hydration induced melting causes rocks to melt in subduction zones when water from the subducting plate lowers the melting temperature of the mantle above 40. What the Ring of Fire refers to. Refers to the line of volcanoes that wraps around the Pacific Ocean, where the Pacific plate subducting into the surrounding plates 41. Why there are fewer active volcanoes in the southwestern US. There is no active subduction zone in the Southwestern US, which leads to fewer volcanoes there than in the Northwestern US 42. The process that causes hot rocks to melt at hot spots. The base of the mantle is heated by the outer core, causing a plume of solid, buoyant mantle to rise until it reaches the lithosphere, where it begins to melt due to depressurization, causing volcanism 43. Where the rising plume originates from at hot spots. The plume is made up of solid, buoyant mantle that has been heated by the outer core 44. Where a hot spot plume melts. A hot sport plume melts at the base of the lithosphere 45. Why hot spots lead to a line of volcanoes. The hot spot does not move, but the tectonic plate move over them, leaving a trail of volcanoes, such as Hawaii. Once the volcano moves away from the hot spot, the volcano becomes dormant 46. Where hot spot tracks found. All over the world, hot spot tracks on the same plate tend to move in the same manner, showing plate motion 47. The process that causes hot rocks to melt at mid-ocean ridges. Mantle experiences depressurized melting at mid-ocean ridges 48. What viscosity is a measure of. Viscosity is a measure of how easily a fluid flows 49. The kind of volcanos produced by low viscosity lava. Low viscosity lava leads to the formation of shallow sloped shield volcanoes 50. That the big island of Hawaii is the tallest mountain on Earth. True, Mauna Kea on the big island of Hawaii is the tallest mountain on Earth when measured from the seafloor 51. How a stratovolcano forms. Stratovolcanoes form due to alternating layers of pyroclastic flows and high viscosity effusive lava flows 52. The kind of volcano that forms when tephra is thrown out of a volcanic vent. 3
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Cinder cones are created when highly viscous lava and tephra is thrown out of a volcanic vent 53. What an effusive volcanic eruption is. An effusive lava flow is when magma can flow up to the surface through a vent or crack without building up pressure 54. Why pressure in magma builds up as it rises toward the surface. Magma contains dissolved gas at depth, and this gas forms into bubbles as it rises to the surface. Since gas bubbles take up more volume, pressure builds within the magma 55. What volcanic ash is. Volcanic ash is made of the shards of volcanic bubbles, broken glass 56. The combination of magma viscosity and gas content that leads to effusive eruptions. Effusive eruptions have a low gas content, lo viscosity, and a higher temperature 57. The most powerful type of explosive eruption. The most powerful type of explosion is a Plinian eruption. Can send columns of pulverized rock and ash 10s of miles up into the atmosphere 58. About how many volcano-related deaths have occurred in the past 500 years. More than 250,000 people 59. The hazard near a volcano that leads to the least number of deaths. Lava is the least dangerous volcanic hazard 60. The hazard near a volcano that leads to the greatest number of deaths. Pyroclastic flows are the most dangerous volcanic hazard 61. That volcanic flows can sometimes be stopped by spraying water on them. Sometimes water can stop lava flows. It worked in Iceland in 1973, but failed in Wahaula National Park in 1989 62. That volcanic flows can sometime be redirected. Sometimes volcanic flows can be redirected, successfully worked in Sicily in 2001 63. Characteristics of volcanic ash. Leftover from magma gas bubbles, smaller than grain sands, Hard, abrasive, corrosive, electrical conductive, doesn’t dissolve in water, not fluffy, 15 cm of wet ash can collapse a roof, 5 cm can kill crops, and 1 mm will close an airport 64. Characteristics of pumice. Volcanic rock with so many trapped gas bubbles that it floats, very lightweight 65. What a pyroclastic flow is. The heavier parts of an explosive eruption that run down the flanks of a volcano at up to 200 mph. Powered by expanding hot gases at over 1000 degrees C 66. That pyroclastic flows can sometimes be directed away from inhabited areas. Pyroclastic can sometimes be redirection, in Unzen Japan there are channels that redirect pyroclastic flows from residential areas 67. Why lahars are dangerous. A lahar is an avalanche of ash, soil, rock, and water that can occur days or even months after an eruption, can reach other 10m high 68. The time frame for volcanic gases to make lakes very acidic. Volcanic gases can turn lakes to sulfuric acid, but it would take weeks or months 69. What killed almost 2000 people in Cameroon in 1986. A cloud of carbon dioxide from the Cameroon volcanic Lake Nyos killed almost 2000 people, suffocating them 70. What a harmonic tremor is. A small earthquake in terms of shaking that last a very long time (many minutes). Happens when magma moves underground 71. That some volcanic eruptions can be predicted a few days before they occur. 4
Volcanic eruptions can generally be predicated, some precursors being a buildup of pressure underneath the surface, rapid ground deformation, gas release increases, and an increase in earthquake frequency Unit 6 – Volcano Catastrophes 72. Why the destruction of Pompeii in 79 AD is historically remarkable. 16000 people were killed, a remarkable description of the eruption was written by Pliny the Younger, and Pompeii was covered in 80 ft of ash, preserving the bodies of those who died 73. The kind of volcano that Mount Vesuvius is. Mount Vesuvius is a Stratovolcano formed by a subduction zone along the coast of Italy (magma is generated by hydration induced melting) 74. The volcanic process that created Mount Vesuvius. Hydration induced melting 75. How Pompeii was preserved for 2000 years. Volcanic ash from the eruption solidified and preserved all of the bodies and buildings 76. That it was only the volume of the bodies (and bones) of the Pompeii that were preserved. Decaying bodies left open spaces in the ash that were then filled with plaster in order to create molds of the bodies 77. Who Pliny the Younger was. Pliny the Younger was a lawyer, author, and magistrate of ancient Rome who wrote down the account of the eruption of Mount Vesuvius and the destruction of Pompeii (nephew of Pliny the Elder, who died trying to rescue people from the Mount Vesuvius eruption) 78. Who Pliny the Elder was. Pliny the Elder was a naturalist and commander of the Roman Navy who died trying to rescue victims of the Mt Vesuvius eruption 79. Why Yellowstone is considered a hidden supervolcano. There is no obvious volcano, but there have been 3 major explosive eruptions there in the last 2 million years, with 2 being super eruptions 80. Why geysers erupt while hot spring do not. Hot springs are continuously replenished due to straight plumbing, but geysers erupt periodically due to bends in the plumbing, field by hot water reservoirs heated by magma 81. How we know Yellowstone is a hot spot volcano. We know that Yellowstone is a hot spot volcano because it lies at the end of a trail of extinct volcanoes and the trail of volcanic flows that lead up to it 82. What the Volcano Explosivity Index (VEI) rating is based on. The VEI rating is based on the volume of ash and rock ejected from the volcano 83. How different VEI ratings compare to each other. Each VEI rating increases by a magnitude of 10 84. The percent of the U.S. that was covered by ash from Yellowstone’s supereruptions. A little bit under half of the US was covered by volcanic ash 85. How a caldera forms. Calderas form when a magma chamber collapses in on itself after an eruption 86. How many very large eruptions has Yellowstone experienced in the past 2.1 million years. There have been 3 large explosive eruptions at Yellowstone in the past 2.1 million years, two of which were supereruptions. We know this because there are 3 calderas and several layers of volcanic ash 87. The evidence for very large explosive eruptions at Yellowstone in the past. There are 3 large calderas at Yellowstone that are associated with pyroclastic flows, and there are indications from volcanic ash 5
88. How volcanologists monitor Yellowstone. Volcanologists monitor earthquake activity, ground deformation, and ground temperature at Yellowstone 89. How we know the size of the current magma chamber under Yellowstone. Yellowstone’s magma chamber has been imaged by measuring the change in speed of seismic waves as they travel under the park 90. How we monitor changes in pressure of a magma chamber. In order to monitor the changes in pressure of the magma chamber, we use GPS to measure the uplift of the ground (when volcanic gas is released, there is a drop in pressure and ground elevation) 91. How large explosive volcanic eruption influence climate. These massive explosive eruptions emit large amounts of SO2 which reacts with oxygen and water vapor to create sulfuric acid droplets, the ash and sulfuric acid droplets block sunlight and cause global cooling, greatly reducing the global temperature due to how long they can remain in the atmosphere: the sulfuric acid droplets stay aloft longer than the ash and can be more detrimental to climate. 92. The volcanic eruption that influenced Mary Shelley to come up with Frankenstein. The 1816 Eruption of Mt. Tambora 93. Why the Toba supereruption 74,000 years ago is considered such an important event. The Toba supereruption (VEI 8) in Sumatra 74,000 years ago led to global cooling that almost wiped out humanity: Toba caused a 6 to 10 year cooling of 3 to 5 degrees C which may have triggered the onset of a 1000 year long ice age, this ice age reduced the human population to under 10000 mating pair (maybe as few as 1000). 94. What giant flood basalts are. Giant flood basalts are relatively large volcanic flows that occur over relatively short time periods, it forms when mantle plume heads first reach the surface then melt due to depressurized melting 95. What giant flood basalts originate from. They originate from mantle plume heads reaching the surface and then melting due to depressurization 96. How giant flood basalts caused extinction events. The dinosaurs may have gone extinct 65 million years ago when an steroid impact triggered the Deccan Traps giant flood basalt, large amounts of greenhouse gases led to global warming and acid rain. 6
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