Earth Science Answer Key

● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Which of the following best describes why the 2010 earthquake in Chile caused a large tsunami while the 2010 earthquake in Haiti only caused a small and local tsunami? ○ The earthquake in Haiti was the result of motion on a transform boundary, which does not produce any vertical motion of the sea floor, whereas the Chilean earthquake was the result of motion along a convergent plate boundary, which does. Transform boundaries are classified under which type of fault? ○ Strike-slip What role do transform boundaries play? ○ Transform boundaries connect other segments of plate boundaries. Do fracture zones near transform boundaries play a role in plate motion? ○ No, fracture zones play no role in plate motion. What is the relationship between transform boundaries and mid-ocean ridges? ○ Transform boundaries connect segments of mid-ocean ridges. In elastic rebound theory, what must occur to produce an earthquake? ○ Enough stress must build up over time on a fault to overcome friction. When a fault is expressed at the surface, it is called a __________. ○ fault scarp The name of the site where slippage begins and earthquake waves radiate outward is called the __________. ○ Hypocenter If the stress applied to the rock is greater than rock strength, what happens? ○ Blocks of rock will slide relative to one another along a fault, causing an earthquake. The hanging wall moves __________ relative to the footwall in a __________ fault. ○ down; normal dip-slip Which of the following might be seen where strike-slip movement has occurred? ○ offset fences How does triangulation determine the epicenter of an earthquake? ○ On a map, a circle is drawn around each of three recording stations, with the radius being the distance from the station to the epicenter of the earthquake. The epicenter is located where the three circles intersect. ________ is the maximum possible damage designation on the Mercalli scale. ○ XII The 2011 earthquake and tsunami in Japan killed approximately 21,000 people while the 2010 earthquake in Haiti killed approximately 316,000 people because ________. ○ the construction methods in Haiti were not as good as those used in Japan Which of the following best describes how scientists help the public prepare for an earthquake event? ○ Scientists cannot predict when exactly an earthquake will occur, but they can identify tectonically active areas that are likely to produce earthquake activity and let the public know they are in an earthquake-prone area. Look at the accompanying map showing the locations of the 15 largest earthquakes in the world since 1900. Imagine an earthquake occurs at location 2 on the map (southern ● ● ● ● ● ● ● ● ● ● ● ● ● ● Alaska) that could generate a tsunami. Which of the following statements are most accurate? ○ All locations (except 9) could benefit from an alert that an earthquake occurred at location 2, because they are near the ocean and might experience a resultant tsunami. ○ All islands in the middle of the Pacific Ocean should also receive warnings. Look again at the map. An earthquake at which of the following locations could cause a tsunami? ○ All of the locations except 9 could produce tsunamis, because all are subduction zones involving at least one oceanic plate. Earthquakes with a deep focus are most often associated with which of the following tectonic settings? ○ oceanic trenches As stress is applied to rocks and deformation occurs, which of the following terms best characterizes the energy that is stored in the process? ○ elastic energy Which of the following responses provides the best reason for why the asthenosphere is not capable of storing elastic energy? ○ Elastic energy can only be stored in cold, brittle rocks. The ocean ridge systems that make up the major divergent plate boundaries are a source of frequent ________. ○ small earthquakes In North America the highest potential for large tsunamis is in the coastal regions of ________. ○ the Pacific Coast and Hawaii Oceanic crust is ________ than continental crust. ○ Denser The velocity of seismic waves generally ________ with depth in the earth. ○ Increases When Mt. St. Helens erupted in May of 1980, ash blew as far away as ________. ○ Oklahoma Why were so many trees knocked down during the Mt. St. Helens eruption while that was not true of the Kilauea volcano? ○ The force of the blast from Mt. St. Helens caused the trees to be knocked over, while the Kilauea volcano was much less violent. ________ tend to increase the explosive potential of a magma body beneath a volcano. ○ High viscosity and high dissolved gas content Which magma type has the lowest viscosity? ○ Basalt The viscosities of magmas ________ with increasing percentages of silica. ○ Increase ________ magma is the most abundant type of magma erupted on Earth. ○ Basaltic ● ● Kilauea is an example of a ________. ○ shield volcano Where can we find the most active volcanoes in the world? ○ Hawaii