Name Caleigh Kehoe Learning Unit 5 Tsunami Review Ques ons This assignment is designed to assess your understanding of Unit 5 and includes some of the Ques ons for Review at the end of Chapter 5 from your text plus a few addi onal ques ons Each ques on can be answered in one to two sentences Please limit yourself to a maximum of three sentences Access the assignment complete it with ANSWERS IN A DIFFERENT COLOR FONT as a separate le and send it back for evalua on and grading through the assignment tab by or before the due date 1 How many tsunami waves are generated when an abrupt disturbance such as an earthquake ver cally displaces the water column There are lots of waves generated since a tsunami us known as a wave train this means that the waves come one aVer the other The waves keep coming for up to an hour aVer the earthquake 2 Of the three main types of fault movements strike slip faults normal faults and reverse thrust faults which can and which cannot cause tsunami Why A strike slip fault cannot cause a tsunami because the fault movement is only back and forth Due to the fact it is not up and down there is no ver cal displacement of the water like there is with normal and reverse faults 3 How dangerous are tsunami waves in the open ocean And why Tsunami waves in the open ocean are not dangerous due to the depth of the ocean the waves are low The slopes of the waves are gentle and they are far apart from one another so many people might not expect to no ce them 4 Which is the more dangerous loca on for a tsunami a straight stretch of open coast or a bay Why The more dangerous loca on for tsunami is a bay because it will concentrate the energy of the tsunami causing amplifying e ects of the tsunami 5 What is oVen the rst indica on of the arrival of a tsunami at the coast The rst indica on of the arrival of a tsunami at the coast is a rapid drop in sea level 6 For a subduc on zone earthquake o the coast of Oregon or Washington how long would it take for a tsunami wave to rst reach the coast For a subduc on zone earthquake o the coast of Oregon or Washington it would take 15 to 20 minutes for the tsunami wave to reach the coast 7 What are the approximate mes between tsunami wave crests The approximate mes between tsunami wave crests is 10 30 minutes 8 Which wave of a major tsunami is likely to be the highest rst fourth tenth The fourth wave of a major tsunami will most likely be the highest 9 In December 2004 a pair of closely related natural disasters killed tens of thousands of people Case in Point Lack of Warning and Educa on Costs Lives Sumatra Tsunami 2004 a What was the ini al event not the one that killed most of the people The ini al event was an earthquake in a subduc on zone caused by a thrust fault movement b Where speci cally was that ini al event c What secondary event the one that killed most of the people was caused by the The ini al event was in Asia speci cally o the southwest coast of Sumatra in Indonesia ini al event noted above A tsunami was the secondary event which killed a lot of people d Explain concisely and in detail exactly how the ini al event was related to the secondary event The ini al event was related to the secondary event because there was a thrust fault movement in the subduc on zone a large amount of water was pushed up and ver cally displaced this causing the tsunami 10 There have not been any very large earthquakes on the subduc on zone of the coast of Washington and Oregon in hundreds of years Explain why not and what are the implica ons based on records of past events The last earthquake on the subduc on zone of the coast of Washington and Oregon because the plates are locked It has been 300 years since the last earthquake causing an intense fric on and when there is one it will be massive 11 On low lying coastal ats near Anchorage Alaska the founda ons of buildings dropped below sea level during the giant 1964 earthquake Decades later their founda ons are again above sea level Case in Point Subduc on Zone Earthquake Generates a Major Tsunami a What type of tectonic boundary caused the earthquake and what plate mo ons are involved A subduc on zone boundary involving the plates of the Paci c Ocean oor moving under the con nental margin b Explain what tecon c forces led to the ground sinking and later rising The subduc on zone fault was locked but over me the ocean oor descended and pulled with its the con nental margin This caused it to slowly buckle and release the boundary meaning the lock this made the sea oor drop suddenly during the earthquake Since the subduc on zone fault is again locked the edge of Alaska is rising 12 What type of event has repeatedly generated high tsunami waves in Lituya Bay of southeastern Alaska Be speci c Case in Point Immense Local Tsunami from a Landslide Lituya Bay Alaska 1958 Due to huge rock falls and landslides caused by earthquakes in 1958 it was a strike slip at caused the high tsunami waves 13 List some of the ways volcanoes can generate tsunami The underwater or above water explosions and shockwaves of volcanoes can generate a tsunami due to the displacement of water Landslides from the erup on can move into the water quickly causing the displacement that generates a tsunami The volcano can collapse into itself causing a caldera which will also displace a large amount of water 14 How are tsunami waves in the Atlan c Ocean likely to be generated Tsunami waves in the Atlan c Ocean likely to be generated by the collapse of the ank of an oceanic island volcano in the Canary Islands 15 Why are even good swimmers oVen killed by tsunami waves Tsunami waves carry a large amount of debris with them which can hit the good swimmers and kill them
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