GEOL 353 Exam (long answers)

According to this week's video (NOVA - Inside the Megastorm) what unusual meteorological conditions affected the path of Hurricane Sandy? List at least 3 unusual conditions.

1) Ocean temperatures were warmer, so the severity of the hurricane was able to be carried and maintained much farther north than normal. 2) Since temperatures were warmer, the jet stream did not behave the way it normally does; instead of pushing the hurricane further east away from land, it actually pushed Sandy west and toward densely populated cities including New York. 3) At the same time that Sandy was occurring, another winter storm was occurring as well. These two storms joined forces to make a giant, hybrid storm.

What four steps does the Pacific Tsunami Warning Center take to alert the public of possible tsunamis?

1: When an earthquake occurs, scientists use seismographs to monitor where the seismic waves are traveling. 2: Then, they monitor deep-sea gauges that record the movement of tsunami waves in the open ocean. 3: Once detected, the deep-sea gauges send the recorded information from a surface buoy through satellites to the warning centers. 4: Once they are certain, scientists will broadcast a tsunami warning, causing sirens to sound.

How many deaths are estimated to occur in Portland due to building collapse? List 4 preparations Portland has made to mitigate deaths from building collapse.

650-6,000 deaths are expected to occur due to building collapse. Four preparations Portland has made to mitigate deaths: improving the construction of schools for seismic retrofitting, urban "search and rescue" squads, choosing shelter locations, rebuilding facilities for the Portland Fire Bureau.

How will a Cascadia earthquake impact transportation in Portland? Your answer should describe at least four major impacts on transportation.

A Cascadia earthquake ruins bridges, roads, and tunnels, and our ability to replenish our fuel supply. Hence, the best ways to get around will become via foot, bike, and boat. Transportation problems described above will make it more difficult for people to get around on rescue missions if they are not able to drive a fueled vehicle on collapsed roads, meaning that it could take weeks or even months for emergency responders to get to people.

Part A) Explain the difference between a hurricane, cyclone, and typhoon. Part B) Explain the difference between a tropical depression, a tropical storm, and a hurricane.

A) A hurricane/typhoon/cyclone is when a cluster of thunderstorms form and suck up warm, moist air, and move it high into the earth's atmosphere. The warm air is then converted into energy that powers the hurricane's circular winds. The winds circle around the eye of the hurricane, which is a low-pressure area in the center of the storm system. Both cyclones and typhoons are synonymous to hurricanes, depending on the region of the world in which they occur. In the Atlantic or eastern Pacific oceans, they are called hurricanes. When they form over the Bay of Bengal and the northern Indian Ocean, they are known as cyclones. In the western Pacific, they are referred to as typhoons. B) A tropical depression is formed from disturbances that take energy from warm waters, and are marked by an organized system of thunderstorms with wind speeds of 25-38 mph. A tropical storm is when the center of the depression intensifies and its winds move at more than 39 miles an hour. A hurricane is when the storm's winds hit a constant speed of 74 or more miles an hour.

A) Name two natural hazards we have discussed this term that can trigger landslides. B) Name at least one more natural hazard that we have not discussed, but that can also trigger landslides.

A) Seismic and volcanic activity B) Floods: often occur in conjunction with or cause landslides.

Describe how early warning systems for earthquakes (for example, ShakeAlert) rely on differences in the arrival times of P-waves and S-waves to give people time to prepare for earthquakes. Also include at least three examples of the types of precautions these systems allow for.

Early warning systems need many more than 3 seismic stations in order to work. 3 stations are enough to locate earthquakes, but early warning systems need a much more dense array of seismic stations. This is why most of the west coast does not have a fully functioning early warning system - we don't have enough seismic stations in place. Here are the main reasons that you need to know about how early warning systems use differences in the arrival times of P-waves and S-waves to give people warning: 1. P-waves travel faster than S-waves, so they are registered first by the early warning system. S-waves travel slower and will arrive seconds to minutes later (depending on how far away the epicenter of the earthquake is). 2. P-waves do not cause damage, but S-waves do. 3. The difference in arrival time between P- and S-waves allows people to have several seconds to minutes warning before the damaging S-waves arrive. This is why these systems work - if the more damaging S-waves arrived first, early warning systems would not work because damage would be caused as soon as these waves arrive. The lag time between the waves is the same lag time that gives people warning. Good examples of precautions these systems allow for. Since the warning time is only a few seconds to minutes, these systems allow for automated precautions like shutting down gas lines, trains, machinery, etc. and for people to make very limited preparations, but they don't allow for preparations that take longer - like mass evacuations or gathering emergency supplies. Three examples: -Public and private transportation can halt, and people can safely exit vehicles or place them in a less hazardous area. -Medical procedures can also be put to a halt to prevent dangerous accidents. -Construction can stop so that workers can evacuate the dangerous machinery.

Describe three methods scientists use to monitor volcanoes for signs of activity. For each method, explain how the information is collected (what is measured, or what type of equipment is used), and what the information tells scientists about the volcano.

Earthquakes - Scientists will monitor tremors in the land surrounding a volcano using a seismometer in order to detect unusual activity. The seismometer measures ground vibrations in real time, and this information tells scientists whether the activity occurring is normal, or unusual in any way. Deformation - Scientists use GPS data for volcano monitoring. In order to collect data for volcanic activity, multiple receivers are placed around a volcano as a GPS network, where scientists can get a larger view of which areas of the volcanoes surface are moving and also the speed and direction of the movement. The data collected in these areas constructs a larger picture of volcano deformation, so that scientists can get an idea of what is happening beneath the surface. Gas and water - During non-eruptive times, direct measurements of gas levels can be taken from the ground. To sample these volcanic gases, scientists collect them from fumaroles, and then analyze them in the laboratory. Once many samples have been analyzed, scientists can determine which areas have a high volcanic gas concentration; meaning, they can determine which areas are prone to more volcanic activity. In all of these cases scientists are looking for ways to determine if magma is moving beneath a volcano, which could indicate that an eruption might occur. Small earthquakes, changes in the ground surface (elevation or tilt), and changes in gas emissions can all indicate that magma is moving toward the surface.

When you created your own volcano on the National Geographic - Forces of Nature website, what criteria resulted in explosive eruptions? What criteria resulted in effusiveeruptions? (There were two criteria that you experimented with in this exercise, be sure to describe each of them.) Of the four types of volcanoes listed in this exercise, which ones tend to erupt explosively? Which ones tend to erupt effusively?

High levels of both dissolved gas and silica result in explosive volcanoes. High dissolved gas levels and low silica also resulted in an explosive volcano. To create an effusive eruption, low dissolved gas levels and either high or low silica levels were required. Meaning, the gas content seems to be the factor controlling whether a volcano is explosive or not. Of the four types of volcanoes listed in this exercise, both cinder cone and composite volcanos erupt explosively. Lava dome and shield volcanoes, however, erupt effusively.

Explain what caused the March 2011 earthquake in Japan and the December 2004 earthquake in Sumatra. How were these two events similar? Your answer should include a brief description of what is happening to the tectonic plates in both regions.

Japan: The march 2011 earthquake occurred along a subduction zone, where the Pacific plate slid underneath the Eurasian plate. Since both of the plates are rough and stick together, they built up a lot of energy that was accumulated and finally released through the earthquake. Sumatra: The December 2004 earthquake occurred as a result of the India plate subducting beneath the Burma plate. These two events are similar because they both involved plate subduction as the cause. A tremendous amount of strain builds up at subduction zones as one plate slides beneath the other, then is released in a large earthquake.

Explain in your own words what mitigation means. Give at least one example from this week's lecture or reading material of: 1) Ways we can mitigate as a society against earthquakes, 2) Ways we can mitigate as individuals against earthquakes.

Mitigation definition: The general act of reducing or eliminating the seriousness or painfulness of something or some action. In terms of this class, mitigation means taking steps to reduce the impacts and risks of natural disasters before they occur. 1) As a society, building earthquake-proof buildings and houses is very important. In order to make these buildings resistant, we must we must tie the roof, walls, and foundation into a rigid box that holds together. Another thing we can do is install an early warning system so that individuals are able to prepare themselves. 2) As individuals, we must follow safety protocols. Specifically, if we are indoors, we must stay there and make ourselves safe by standing against a wall near the center of the building, in a doorway, or get underneath sturdy furniture. However, if outdoors it is important that we stand in an open space away from power lines or buildings. These steps must be taken before a disaster occurs.

According to the DOGAMI interactive map showing landslides in Oregon, where do most landslides in the state occur? What two factors do you think have the most influence on where landslides occur in Oregon? Your answer should explain why the majority of landslides occur where they do, and why landslides are less common in other regions of the state.

Most landslides occur in the western part of the state, but they occur in specific areas, not equally throughout the entire western part of the state. Most landslides in Oregon occur in the Coast Range and along the west slopes of the Cascades. The reasons for this are steep slopes and lots of precipitation. The landslides shown on the interactive map are historical landslides - meaning they have occurred much more recently than the last big Cascadia earthquake. Earthquakes in Oregon can definitely trigger landslides, but most of the landslides on the map occurred because of steep slopes and heavy precipitation, not because of earthquakes. Bottom line - the Coast Range and the west slopes of the Cascades are prone to landslides regardless of seismic activity. Earthquakes will make landslides even more common in Oregon, but they are already common. Eastern Oregon has fewer landslides, but so do flat areas in western Oregon - for example the Willamette Valley (very flat, and hardly any landslides!).

What is the difference between natural phenomena (or natural events), natural hazards, and natural disasters? Answer in your own words, using a sentence or two to explain each term and giving an example of each term in your explanation.

Natural phenomena are mere physical events that can be separated into atmospheric, geologic, and hydrologic categories. An example would be a volcano occurring on a deserted island. Natural hazards are when the phenomenon has the potential to inflict damage on humans or human civilization. An example would be a less extreme earthquake. Natural disasters, however, are considered a subset of both hazards, and in turn phenomena. An event is considered a disaster when they have a "major" impact on humans or human civilization. Natural disasters are separated from hazards by the magnitude of damage they cause to a human community. An example would be a mega tsunami hitting the coast of San Francisco.

What is a reinsurance company? Why do these companies have a special interest in keeping track of natural hazards and natural disasters?

Reinsurance companies are large companies that insure "normal" insurance companies. Individuals (you and me) purchase insurance from "normal" insurance companies, and these insurance companies purchase their own insurance from reinsurance companies. Reinsurance companies must track natural hazards/disasters because their ultimate goal is to reduce their exposure to loss. They must be aware of the potential damage these hazards could cause, and how that damage would affect the insurance that covers them. The more data they can collect about where and why disasters occur, the better they can predict their financial outcome.

Describe 4 ways that levees can fail.

Seepage: Water seeps through the levee or levee foundation. Stability: A section of levee sloughs off because of water pushing against the levee. Erosion: It steepens the levee slope so that it's unstable to the point of collapse and inundation. Height deficiency: More flow comes in than what the levee is designed to withstand, so water is able spill over the top of the levee.

What is meant by the term 100-year flood? Your answer should include something about the magnitude and the percent chance of happening in any given year. Can more than one 100-year flood occur in a 100 year time span? Can more than one 100-year flood occur in 1 year?

The term 100-year flood means that a flood of a certain magnitude has a 1-percent chance of happening in any given year. Meaning, although it has a 1-percent likelihood of occurring, a flood with a certain magnitude has the potential to occur 2 years in a row. Meaning, more than one 100-year flood can occur in a 100 year time span, and also more than one can occur in 1 year.

Describe the two most effective methods of landslide mitigation, or how to reduce the effects of landslides. If either of these methods needs further explanation (for example, details about how landslide hazards are reduced) include this in your explanation.

The two most effective methods of landslide mitigation are avoiding construction on steep slopes and stabilizing slopes. Slopes can be stabilized by preventing ground water from rising in the landslide mass. This can be achieved by covering the landslide with an impermeable membrane, minimizing surface irrigation, among other methods.

Why are the west coast, the Rocky Mountain region, and the Appalachian region more susceptible to landslides than other parts of the U.S.?

These areas all have steep slopes.

When you created your own hurricane, what 3 things were needed in order to generate a hurricane?

When I created my own hurricane, I needed warm ocean temperatures, high humidity, and low pressure.

What causes the polar jet stream to become "wavy"? (Be sure to include a description of what is happening to different air currents.)

With rising global temperatures, the movement of the jet stream is being affected as a result. Since the polar regions are warming at a higher rate than the rest of the world, the temperature contrast that drives the movement of the jet stream has decreased. As a result, jet streams appear "wavy" because they are becoming slower and weaker. Since there is less cold air on the north front of a jet stream as the temperatures of polar regions rise, air currents from that side are becoming weaker as a result. Therefore, the greater force of warm currents from the south overpower the weaker, cold currents, causing storms such as hurricanes to be pushed in areas that they don't normally frequent.