Geologic Hazards

Which is the most common cause of landslides?

Slope saturation by water

What is the most dangerous result of a hurricane once it reaches land?

Storm surge

Which is the most widespread and frequent volcanic hazard?

Tephra (or volcanic ash)

How much economic damage is caused by floods each year in the United States?

About 6 billion dollars

The polar jet stream is created by:

Convergence of cold air descending from the Arctic and warm air rising from the tropics.

What type of plate boundaries generate the most tsunamis?

Convergent plate boundaries - sunduction zones

Because of the Coriolis Effect, hurricanes rotate in the Northern Hemisphere and in the Southern Hemisphere.

Counterclockwise, Clockwise

What are the main parts of a hurricane?

Eye Feeder bands Eye wa

What is the most turbulent part of a hurricane?

Eye wall

Which of the following volcanic gases are hazardous to people, animals, agriculture, and property?

Hydrogen halides (HF, HCl, HBr,Hydrogen sulfide (H2S),Carbon dioxide (CO2),Sulfur dioxide (SO2

Sudden melting of glaciers on volcanoes can generate which hazards?

Lahars

What four factors are used to rate the severity of a natural disaster?

Magnitude (size of the event) Deaths caused by the event Economic Damage Lasting Legacy

Most earthquakes occur along the edges of

Oceanic and continental boundaries

Describe 4 ways that levees can fail.

Seepage: When water seeps through the levee foundation. Stability: When a section of the levee breaks off allowing water to break through. Erosion: Erosion causes the levee to slope and can cause the levee to break off into the water. Height: When the height of water surpasses the height of the levee.

What hazards are closely related to earthquakes?

Subsidence, Liquefaction, Ground Displacement, Flooding, Tsunamis and Fires

Which scale measures an earthquake's intensity based on the observed effects on people and structures

The Mercalli Scale

Which of the following best describes how the stability of levees is fixed?

The levee is widened and flattened.

What 3 general regions of the United States are most susceptible to landslides?

The west coast The Rocky Mountain region The Appalachian region

In general, subduction zone earthquakes in the Pacific Northwest are much larger than any recorded earthquake that has occurred in California. T OR F?

True

Winds in the polar jet stream can travel at speeds greater than 100 mph. T OR F

True

all parts of the world

What part of the world experience natural hazards?

A pyroclastic flow can best be described as: Correct Answer

A flow of hot gas and ash

Tsunamis waves are caused by

A sudden displacement of water

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) 1.Volcanic eruptions can cause volcanic debris flows. 2. Earthquakes can trigger the dilation of soil materials, ground failure, and allows rapid infiltration of water which all cause landslides. B) Monsoons or heavy rainfall.

How high were the tsunami waves created by ancient landslides in Hawaii?

About 1,000 feet (about 300 meters).

How many people are killed by floods each year in the United States?

About 140 people

Which of the following best describes how erosion of levees is fixed?

Building a layer of rock to strengthen the levee and it's foundation

If a large asteroid landed in the Pacific Ocean between the Hawaiian Islands and the west coast of North America, what would be the impact of the tsunami waves? How likely is it that this event would occur?

They would wash out coastal cities on the west coasts of Canada, the U.S. and Mexico, and would cover most of the coastal areas of Hawaii. Highly unlikely

What types of weather events are associated with a "wavy" polar jet stream?

Tropical storms along the east coast, for example Hurricane Sandy. Severe snowstorms along the east coast. Droughts in the Midwest. Unusually cold winters in Europe

Which of the following best describes how seepage from levees is fixed?

Digging a trench into the levee and filling it with a watertight wall.

Which tectonic features are associated with volcanic activity?

Divergent Plate boundaries, Convergent plate boundaries and hotspots

What types of events cause tsunamis?

Earthquakes, Landslides, Volcanic Eruptions, and Meteor impacts

Of the hundreds of storm systems generated in tropical regions every year, how many typically develop into hurricanes?

Less than 50% (40 to 50)

How old are the oldest levee systems in California? (And also throughout the rest of the country.)

More than 100 years old

Rising temperatures in the arctic make the jet stream _________ "wavy," increasing the likelihood of ________severe storms.

More;more

Which natural hazard occurs the slowest?

Droughts

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.

Estimates range from 650 to 6,000 Portland has: 1. Retrofitted or rebuilt all 30 of its Portland Fire Bureau facilities to better respond to strong earthquakes. 2. Portland has executed a $482 million bond project to improve schools for earthquakes. 3. The Portland Fire Bureau also has developed an "urban search and rescue" team of community members that are trained to find people in rubble. 4. Portland has retrofitted the Pioneer Courthouse to have base-isolation in the case of an earthquake that would allow functioning post earthquake event.

One way that Oregon and Washington have mitigated against loss of life during large tsunamis is by building vertical evacuation structures in all coastal towns and cities. T OR F

False

The best definition for the term volcano is a tall cone-shaped mountain that erupts lava. T OR F

False

When you created your own volcano on the National Geographic - Forces of NatureLinks to an external site. website, what criteria resulted in explosive eruptions? What criteria resulted in effusive eruptions? Of the four types of volcanoes listed in this exercise, which ones tend to erupt explosively? Which ones tend to erupt effusively?

Gas content is the most important control on how explosive an eruption will b xplosive eruptions occur when dissolved gas content is high, effusive eruptions occur when dissolved gas content is low. But silica content can be either high or low. High silica content results in more explosive eruptions, e.g. composite volcanoes; low silica content results in less explosive

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.

Hurricanes develop over the Atlantic and Eastern Pacific Ocean Cyclones develop over the bay of Bengal and the Northern Indian Ocean Typhoons develop over the Western Pacific Ocean. A tropical depression is when thunderstorms become combined with low-pressure surface winds and high pressure upper-level winds combine and rotate in circular motions caused by the Coriolis. This is the beginning of a hurricane. Tropical depressions drive more warm air into the system which becomes cooled and releases energy into the turbulent weather system which turns it into a tropical storm. When winds reach 39 mph, it is considered a tropical storm. When this system becomes stronger and winds become faster reaching 74 mph, it becomes categorized as a hurricane. These storm systems are categorized depending on their wind speeds. just need to include that storms are not classified as tropical depressions until they have wind speeds of 25 mph (25-38 mph).

Which of the following best describes creep landslides

Imperceptibly slow, steady, downward movement of soil or rock

Where in the U.S. do landslides occur?

In all 50 states.

When is the polar jet stream strongest?

In winter months when the temperature difference between warm and cold air in the Northern Hemisphere is at its highest.

Which of the following can trigger landslides on volcanoes?

Intrusion of magma into the volcano Explosive eruptions of the volcano Large earthquakes directly beneath or nearby the volcano Heavy rainfall that saturates the slopes of the volcano

Why are the regions you chose in Question 4 more susceptible to landslides than other parts of the U.S.?

Landslides are primarily associated with mountainous and elevated regions that often receive a lot of rain/snow which characterizes the mountainous regions of The Appalachians, the Rocky Mountains, and the intermountain west. he simplest reason these regions are more susceptible to landslides is because they have steep slopes. And steep slopes is the MOST important factor for where landslides occur.

According to the 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.

Landslides occur all over the state, but historically, the most landslide concentrations occur near the Oregon coast and along the Cascades. Furthermore, the landslide hazard layer displays the highest hazard to be present along the Cascades and northern coast. After zooming in, I noticed that most of the historic data reveals landslides to occur near highways. The areas along the Cascades that are vulnerable are mountainous, and occur quite a significant amount of snow during the winter that melts entirely during the summer, which can saturate slopes and cause landslides. The areas along the coastline are often in mountainous areas that receive a significant amount of rain, which is a primary precursor to landslides. The high desert, such as Bend, and isolated valleys such as the Willamette and Albany are areas that have very low susceptibility. This is because they are not elevated areas with a lot of slopes.

What is produced by the least explosive types of volcanic eruptions?

Lava flows

Explain in your own words what mitigation means

Mitigation occurs when prevention is not 100% attainable. When something cannot be prevented, actions must be taken to decrease the amount of damage that could occur in the event of a disaster. 1) Implement and develop Shake Alert systems 2) Develop a safety plan for earthquakes and tsunamis, work with community to develop safe infrastructure.

How would you describe the path of the jet stream shown in the Boston Globe article?

More "wavy" than usual, bringing heavy snow storms to New England.

What parts of the U.S. are at the highest risk for earthquakes

Most of Alaska Western states, especially Washington, Oregon, Nevada and California Hawaii, especially the big island The region near the borders of Kentucky, Tennessee, Arkansas and Missouri

How are mudflows different from landslides?

Mudflows are rivers of liquid and flowing mud, they contain less solid material than landslides.

What is the difference between natural phenomena (or natural events), natural hazards, and natural disasters?

Natural phenomena are environmental occurrences that include the climate, geology, the atmosphere and the hydrologic earth systems that occur independently from humans. Examples of natural phenomena include earthquakes, volcanic eruptions, hurricanes, tsunami's etc. These phenomena become natural hazards when the event have the potential to damage human life. For example, the natural phenomena of a tsunami only becomes a natural hazard if there are civilizations that are vulnerable to such an occurrence. Furthermore, a natural hazard becomes a natural disaster when such an event damages human welfare in a severe way.

What is a levee?

Natural river banks that are elevated from the river bed. Manmade river banks that are elevated from the river bed.

Do typical homeowners insurance policies cover geologic hazards like landslides?

No

What parts of the world are impacted by the polar jet stream?

North America, Europe and Asia

describe "slow earthquakes"

Occur over a period of several weeks, cannot be felt even though they release the same amount of energy as a "normal" magnitude earthquake, they occur about every 14-125 months in the PNW, they can act as a warning for a much larger Cascadia earthquake

Which type of seismic waves travel the fastest?

P Waves

Describe how early warning systems for earthquakes (for example, Shake Alert) 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 allow for.

P-waves are low amplitude, they do not cause damage. And since S-waves are higher amplitude, they do cause damage. This is an important reason why these systems work - if the more damaging S-waves arrived first, early warning systems would not work.P-waves are very low amplitude waves of energy that travel very quickly as opposed to the much slower, much higher amplitude energy waves of S-waves. By detecting a P-wave and sending an immediate warning to the public, it may provide a warning system that notifies people in time to find safety. However, this warning only allows a few minutes to prepare, which is not a lot, but it is still something. These warning systems are created to save lives: 1. to warn those in dangerous buildings or working with dangerous equipment to stop immediately and seek safety. 2. to prevent traffic accidents and city operational transit from bringing further harm to people. 3. to warn people who are located in weak infrastructure that is not up to code, especially in a tsunami vulnerable area.

Which of the following are hazards that exist after flood waters recede?

Pesticides and fuel Untreated sewage Dangerous mold blooms Waterborne diseases like typhoid, hepatitis A, and cholera

Which of the following best describes debris flows

Rapid mass movement of loose soil, rock, organic matter, and water that flows as a slurry downslope.

Earthquake shaking is measured using the following scales:

Richter scale, the moment magnitude scale, the mercalli scale

To determine how far away from a seismograph station an earthquake occurred, scientists plot the difference in arrival times between:

S and P waves

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.

Scientists monitor volcanoes through observing Deformation, Ground Vibration and observe the atmosphere and land changes through Remote Sensing. Observing Deformation: Utilizing scientific instruments on the ground such as GPS, taking surveys and using tiltmeter to record any measurable changes occurring in the earth that may provide evidence for a future eruption. Ground Vibration observations: Geologists through the USGS monitor earthquakes and lahars with sensors because both events are linked to possible eruptions. Remote sensing: Utilizing cameras, thermal imaging and satellites allow geologists to observe changes in the earth above and below the surface, which provides extremely crucial tools in peering into the earth. These tools can help scientists follow magma flows and possible inflation of magma chambers, they can map out where these hazards will effect the most, they can use all of this data to prepare for possible eruptions as well as begin to understand a time-frame for when it will happen Be sure to describe how each method tells us about magma movement below the volcano..

When the polar jet stream gets "wavy" and moves slower, what happens to the weather patterns associated with it?

Storms tend to stall out and stay in one place for longer. Storms become more intense

In general, the most destructive earthquake waves are

Surface waves

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

The crucial bridges that connect Portland as well as the major Interstate that acts as an entry and exit to the city for escape and resources would likely collapse. The ability to get in and out of the city would be almost impossible. Many of the Portland roads are build on alluvial deposits, meaning they will probably crack and sink into the ground. All of the city's road-clearing equipment is stored under the Fremont Bridge ramps, which is also likely to collapse. Finally, most of Portlands fuel supply is obtained by a BP pipeline that runs beneath the Columbia and Willamette Rivers, which would likely rupture in the event of an earthquake, leaving catastrophic leakages and leaving Portland without fuel. Any incoming fuel by truck would be stuck at the collapsed freeway entries. This lack of transportation will leave hundreds of thousands of people stranded, without food or water (unless they planned properly), without electricity for months. Those who are greatly injured would not have easy access to any medical facility by car as the city would be an absolutely battle ground of rubble. The broken bridges, roadways, freeways etc, and lack of necessary equipment for cleanup and transport would leave Portland in a state of emergency.

Which of the following best describes how the height of levees is fixed?

The levee is constructed higher, or a flood wall is built.

What part of the atmosphere do winds in the polar jet stream travel?

The lower layers of the atmosphere, where they have a strong influence on weather.

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' refers to flood occurrences having a 100-year recurrence interval based on historical data. For example, the probability of the Soandso River reaching 20 feet is once in 100 years. A flood with this magnitude therefore has a 1% chance of happening in any year. This magnitude and percentage can change according to flow patterns. Yes, more than one 100-year flood can occur in a 100-year time span and more than one 100-year flood can occur in one year.

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

The wavy appearance of the jet stream occurs as denser cold air sinks and deflects warm air regions north. The presence of a strong high pressure system can create a "wavier" jet stream, which makes it easier for weather systems to turn toward the west instead of being deflected by the jet stream to the east. It is the pockets of cold air creeping down from the arctic "sporadically" that run into the warmer tropic air and creates contrasting waves and flows that move through the jet stream toward the east. Yes, colder, more dense air sinks and pushes warm air pockets to the north. This forms steep ridges and troughs (or "waves") in the way the air flows. Less ice in the arctic means warmer temperatures in the north, which makes the jet stream even more wavy. So the jet stream is normally wavy, but it is made even more wavy by climate change

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

These are steps that are taken to alert the public of possible tsunamis, but the first two steps are missing: 1) Locate the earthquake (or other event, e.g landslide, volcanic eruption, etc.) to see if it's capable of generating a tsunami, 2) Determine the travel time of the tsunami by using computer models. After these steps, THEN ocean gauges are checked to see if there is evidence of tsunami waves, and if the waves match predictions from models. If these first 3 steps indicate that a tsunami has been generated, then warnings are issued to the public (but not before the first 3 steps)

What is the effect of wind shears on hurricanes?

They make hurricanes weaker

What direction do winds in the polar jet stream travel?

Toward the east

This week's video showed layers of sand that Brian Atwater found in the pits he dug along the coast of Oregon and Washington. Which of the following best describes how these layers of sand were deposited?

Tsunamis

what unusual meteorological conditions affected the path of Hurricane Sandy? List at least 3 unusual conditions.

Unusually warm Arctic temperatures. Strong high pressure system causing a wavier jet stream allowing the storm to head west toward land instead of east. Climate change/global warming in general. Your answer needs to include at least three of the following (each answer worth 1.5 points): 1. The "Bermuda High" (area of high pressure that forms each summer near Bermuda) was not present. The Bermuda High normally steers hurricanes out to sea rather than toward land. 2. Unusually warm temperatures in the North Atlantic gave the storm more fuel. Good job! (+1.5) 3. Hurricane Sandy merged with another storm from the north (a "nor'easter"), which made the hurricane even more powerful. 4. The polar jet stream was more "wavy" than usual, which pushed Hurricane Sandy west (toward land) rather than east (out to sea).

Which is the most common type of volcanic gas?

Water vapor (H2O)

Once tsunami waves wash inland in populated areas, what do they consist of?

Water, sediments, natural debris, and manmade debris (houses, cars, boats, etc).

Can hurricanes spawn tornadoes?

Yes

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

a company that sells insurance to insurance companies as a form of risk management for insurance companies who have the vulnerability to suffer greatly in the event of a severe natural disaster. 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. There are only a few reinsurance companies in the world. These companies are ultimately on the hook for billions of dollars in losses every time a natural disaster occurs, which means they have a HUGE financial interest in studying natural disasters.. They need the knowledge in order to develop plans and investments.

How many giant landslides have occurred in Hawaii during the past 4 million years? Could they occur again in the future?

at least 15, yes

Are natural hazards rare or common worldwide?

common

In deep water, tsunamis move at _____________. When they reach shallow water in coastal areas, the tsunami _____________ and ____________ in height.

fast speeds, slows down, increases

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.

he two most effective methods of landslide mitigation include education and informing the public, and increasing the stability of steep, vulnerable slopes. Education: Local governments can create land-use policies and regulations that provide citizens with contextual understanding of possible failures, as well as prevent them from putting themselves in a vulnerable situation. Individuals can also inform themselves by obtaining the services of professional geologists and engineers that can evaluate potential hazard sites. Stability: Stability of slopes can be increased by preventing groundwater from rising in a landslide mass by (1) covering the landslide with an impermeable membrane, (2) directing surface water away from the landslide, (3) draining groundwater away from location, and (4) minimizing surface irrigation. Stability can also be increased by building retaining structures at the toe of the landslide or mass is removed from the top. but the MOST effective method is to avoid development in areas that are likely to slide

According to the World Meteorological Organization, every dollar that is invested in disaster preparedness can prevent ________ in economic losses related to disasters.

seven dollars

Which disaster was the most economic costly disaster in human history?

the 2011 Japanese earthquake and tsunami

Based on this week's reading materials, and this week's and last week's videos, how long could the shaking last during a large Cascadia earthquake

Up to five minutes

How many volcanoes are usually erupting worldwide?

about 20

The most common cause of tsunamis is:

earthquakes

Hurricanes can be up to ________ miles in diameter.

1,000

The largest landslide in the world is over ________ thick and more than ________ in area.

1,000 feet, 400 square mile

what 3 things were needed in order to generate a hurricane? Of the 5 hurricanes you generated, which one had the greatest intensity? What category was this hurricane?

1. Low Pressure 2. Warm ocean temperature 3. High humidity #3 hurricane had the highest intensity with winds from 131 mph to 155 mph; it was a category four hurricane. The greatest intensity hurricane should have been a Category 5. It is possible to create 5 different hurricanes and not generate a Category 5, but this is unlikely. And you should ask yourself while doing the exercise if it makes sense that the highest category you generated was a 4, but the scale goes up to 5 and you selected the lowest pressure, warmest ocean temperatures, and highest humidity.

A large subduction zone earthquake in the Pacific Northwest will likely trigger a tsunami with waves ____ feet high and lasting up to ____ hours.

10-15 feet high, 8 hours

Scientists estimate there is a ___ % chance of a M 9+ Cascadia earthquake occurring in the next ____years and a ____% chance of a M 8+ Cascadia earthquake occurring in the next ____years. The frequency of occurrence for these earthquakes is once every 500 years for a M 9+ earthquake, and once every 250 for a M 8+ earthquake. The last Cascadia earthquake occurred____years ago.

10-15, 50, 37, 50, 317

approximately how many earthquakes occur in the U.S. every week

1000 to 2000

Storm surges can be up to ______ high and can extend up to ________ along coastlines.

20 feet, 100 miles

What is the minimum number of seismograph stations a scientist must have data from in order to locate the epicenter of an earthquake

3

What percentage of single-family homes in Portland were built before the first seismic codes, which means they are probably not bolted to their foundations and will be uninhabitable after a large Cascadia earthquake?

70%

Hurricanes can be up to ________ miles in height.

9

Earthquakes can occur along which types of faults

All types

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.

Both earthquakes were the result of a subdection zone at convergent plate boundaries, where one tectonic plate is subducting beneath another creating a fault. During subduction, plates can often get stuck which accumulates a massive amount of energy. When this energy is released due to a fault slip earthquake, the overriding plate experiences abrupt uplift. This is what caused the tsunami's that ravaged both Japan and Sumatra. In Japan, the earthquake occurred near a subduction zone. In Sumatra, the earthquake occurred where the oceanic India plate is subjecting beneath the Sunda plate. both cases, the stress that is released is so large that the resulting earthquake is called a mega-thrust earthquake - these are largest earthquakes that occur anywhere on Earth, and they only occur in subduction zones.