Natural Disasters

List three potential triggers for tropical cyclones. What do all three of these things have in common?

1. intertropical convergence zone 2. easterly waves 3. cold fronts They are all regions of convergence that can produce thunderstorms.

What lessons can the Pacific NW of Canada and the USA learn from the Indonesian earthquake and tsunami of 2004?

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Discuss one weather related consequence of a strong el Nino event in the region of Northern Australia and Indonesia.

A consequence could be drought or wildfires due to subsiding air.

Explain why tropical cyclones never develop near the equator.

Because there is not enough coriolis force to produce a rotating body.

Explain why a nearly stationary tropical cyclone is less likely to be an intense cyclone than one moving at 20 km/h

Because there would be less warm water to generate heat and latent energy. One moving at 20 km/h will be more intense because there will be constant renewal of warm water as a source of energy for the cyclone.

The subduction-related cascade volcanoes of the Pacific NW in the USA and Canada are commonly draped in snow and ice. Why are some communities located far from these volcanoes still at risk from an eruption?

Because these volcanoes have the ability to create lahars and ash fall, which are very mobile and can flow long distances.

Why do people live in areas which are vulnerable to hazardous natural events?

Because they are beautiful areas such as the coast. People like to live near water and therefore many coastal areas are densely populated.

On a global scale, discuss seismic and volcanic hazards in terms of plate tectonics.

Both seismic and volcanic hazards are most frequent along plate boundaries. This is due to stress caused by tectonic plates interacting.

Discuss the relative merits of building a house with brick vs. wood in earthquake prone zones.

Bricks are not reliable, as they don't withstand shock waves of the ground and buildings will easily collapse. Wood is a better material for earthquakes, but they are more prone to fires, which are sometimes associated with earthquakes.

How does a caldera form?

Calderas form due to the magma of the interior of the volcano being drained out, therefore having an empty reservoir to which the roof has nothing to support the weight. The roof will therefore collapse inwards creating a depression.

During what season would you expect most tornadoes in North America to occur? Explain

During the early summer through the summer season. This is due to the increased warm moist air from the gulf clashing with the colder air from the north. During these months, the temperature is warmer and usually more moist and therefore I would expect to see more tornadoes during the summer seasons.

During what month or months would you expect to see the most thunderstorms in the city of Montreal? Explain.

During the summer months because there is much more moisture and heat in the air, which can cause more instability and this is a requirement necessary for the formation of thunderstorms.

List 3 mechanisms that can generate tsunami waves.

Earthquakes, landslides, volcanic activity

What regions of North America are most vulnerable to freezing rain storms? Why?

Valleys are prone to ice storms such as the St. Lawrence River Valley, Newfoundland, Eastern Appalachian valleys, and East of the Cascade Mountains. This is due to cold air damming that is likely to occur in the valleys. In these cold air dams, warm moist air from the gulf of Mexico passes over these domes of cold air and produces the conditions necessary for freezing rain storms.

Do the North Atlantic or the North Pacific Ocean areas have the most intense hurricanes? explain

North Pacific Ocean because the ocean temperatures are warmer in this region.

What is the main volcanic hazard to an aircraft? Give one example of this hazard.

Volcanic ash in the air which can severely damage engines causing aircraft failure. An example of this occurred in Pinatubo, Philippines, in 1991.

What role, if any, did the El Nino event play in the production of the great ice storm of 1998?

The El nino could have possibly played a role in the deep warm layer in the air that produced the freezing rain. It is possible, however el ninos typically don't affect Eastern Canada as much, and there is no direct link between the two events. However, it is possible that warmer temperatures could have helped in the formation of the freezing rain due to the need for a deep warm layer in between 2 cold shallow layers.

Explain the difference between a local tsunami and a distant tsunami.

When there's a distant tsunami, you generally have more time to warn people as the wave is further from impacting civilians. In a local wave, there's a much less chance to warn people, as the wave is propagated much closer to the coastal area.

Given global warming, would we expect to see an upward increase in the number of tornadoes in North America? Explain.

While there is no clear link between increasing tornado activity with global warming, it is likely that there could be more tornadoes due to more warm moist air in the atmosphere. This could lead to more frequent instability, and thus produce more tornadoes.

How do wildfires contribute to debris flows?

Wildfires can cause loss of vegetation and surface erosion which then when it rains, these factors make the soil extremely weak and susceptible to debris flow. The soil without vegetation and after being exposed to wildfires is much weaker therefore debris flows are likely to occur after wildfires.

You are in a rowboat on the open ocean, and a tsunami wave passes you. Would you feel this wave? Explain

You might feel it a bit, but the amplitude of the wave in deep water is usually less than 1 meter, while the amplitude in shallow water can exceed 40 meters. Therefore there's a much lower chance of you actually feeling a tsunami wave in the open ocean.

Explain the difference between hazard and risk

hazard is the potential threat to humans whereas risk is the probability of loss due to a natural disaster event.

What is meant by warm core of a hurricane?

the warmest air being located in the eye of the hurricane.

Discuss three factors that make Bangladesh particularly susceptible to loss of life from a tropical cyclone.

1. close proximity to warm body of water 2. low elevation above sea level 3. very high population density

In subduction zone, earthquakes and landslides are a common occurrence, sometimes generating a tsunami. Explain why these earthquakes and landslides occur frequently in this tectonic environment.

A subduction zone is a converging boundary of 2 tectonic plates, in which the oceanic plate is subducted underneath the continental plate. This shifting of plate boundaries causes stress and friction, which is likely to produce earthquakes. Volcanoes are also associated with subduction zones because as the oceanic plate is pushed underneath the continental plate, it heats up in the Earth's mantle and pushes magma towards the surface.

Explain the difference between a thrust fault and a blind thrust fault.

A thrust fault reaches the surface, a blind thrust fault does not.

Where do the largest earthquakes occur, along divergent, convergent, or transform plate boundaries? Explain your answer.

Along convergent boundaries because the subducting plates cause a lot more friction and pressure.

Where is seismic hazard greatest in Canada and why?

Along the western coast of BC and the Yukon territories since this is on the Cascadia subduction zone and on active strike-slip faults.

Does basaltic lava flow faster or slower than rhyolitic lava? Explain

Basaltic lava flows faster due to its lower silica content and higher temperature than rhyolitic lava.

Explain why Montreal's location makes it an especially preferred location for ice storms.

Because Montreal is located in the St. Lawrence River Valley. The 3 surrounding mountain ranges provide an environment for cold air to essentially become trapped in this valley, creating a dome of cold air. The cold winds coming in from the northeast will get trapped between these 3 mountain ranges which is called cold-air damming and can produce ice storms, like that of the 1998 ice storm.

What atmospheric conditions made the 1998 ice storm so severe as compared to other freezing rain storms?

Because a nearly stationary frontal system stayed trapped for more than 80 hours, which is much longer than typical ice storms. Therefore, the freezing rain kept accumulating creating considerable damage.

The great majority of earthquakes and volcanoes are found at the margins of tectonic plates, while comparatively few occur in the interiors of the plates. Explain this observation.

Because earthquakes and volcanoes both occur on plate boundaries where the boundaries are either sliding or converging in some way. Alternatively, you don't see this type of activity in plate interiors because there are not two plates reacting to each other causing stress.

Why do so many thrust faults occur in the Los Angeles area?

Because it is located near the San Andreas fault line, which is curved, not linear therefore it's causing compression and thrust faulting to occur in the LA area.

Why is Cascadia seismicity low if it's in a subduction zone?

Because it's not able to subduct, it is stuck therefore there is relatively low seismicity and it's characterized by really large but infrequent earthquakes (about only a few hundred years)

The 1883 eruption of Krakatau in Indonesia resulted in the deaths of 36,000 people. Why was the loss of life so high?

Because of pyroclastic flows, volcanic ash, and tsunamis that were produced by this eruption.

Discuss why there are not many hurricanes along the coast of South America?

Because the ocean temperature is not warm enough. There are a particular set of conditions that play into the formation of a hurricane and one of them needs to be warm temperature of ~27 C at least 60 m deep.

Are coastal communities on the Atlantic Ocean more or less vulnerable than those on the Pacific Ocean in terms of tsunamis? Explain.

Coastal communities along the pacific ocean are more vulnerable to tsunamis due to the subduction zone that can produce massive earthquakes, more volcanic activity, and other disasters that can trigger tsunamis.

Would you expect a 4 cm ice storm, or 4 cm snow storm to have a greater impact on the infastructure of the city of Montreal? Why?

Definitely a 4 cm ice storm, because the mass of ice is much heavier than that of snow, which can cause huge damage to power lines, and damage due to falling trees and branches.

What is the impact of a severe el nino event on the weather and climate of Australia and Indonesia? Explain.

During an El Nino, it is likely to see reduced rainfall and warmer temperatures in Australia and Indonesia. Because El Nino events mean that the trade winds could be stagnant or reversed, the typical rainfall that occurs in Australia and Indonesia will be migrating towards the East, therefore the usual rainfall in Austria and Indonesia could be reduced. Because of this, warmer temperature is usually associated with these areas during el nino, because there is less cloud cover due to less warm ocean temperatures and thus less convection.

Discuss the role of both the south Pacific Ocean and the atmosphere in maintaining a strong El Nino.

During an el nino, the easterly trade winds that typically bring warm ocean temperatures to the West are often weakened. This weakening of the winds changes the ocean currents, usually reversing the direction of the warm ocean temperatures. This causes the cessation of cold water upwelling along the coast of South America, and starts downwelling, where cold ocean temperatures are being suppressed by warmer ocean temperatures.

Rift Zones are found on both continents and ocean basins. What type of faulting characterizes these environments? Explain

Normal faults due to the crust being pulled apart

What was the importance of the oceans in helping to create the 1998 Montreal ice storm?

Freezing rain has a shallow cold layer, a deep warm layer warmer than 0C or 32F, and another very shallow cold layer, by the time that liquid water falls into the extremely shallow of cold air at the bottom, there's no time for it to freeze until it hits a surface

How has global warming affected the impacts of weather-related natural disasters? Explain.

Global warming has increased weather-related natural disasters. For example tornadoes have increased as a result of global warming. Hurricanes haven't increased since 1970, but that doesn't mean that there isn't a connection, because even though the amount of hurricanes have remained the same, the intensity of them have drastically increased. Forest fires, heat waves, floods, and droughts are all increased by global warming as well.

Name one affect that global warming has on coastal residents' vulnerability to a future natural disaster.

Global warming, although not directly correlated with an increase in the amount of hurricanes, does affect the intensity of hurricanes. Coastal areas such as Florida are increasingly vulnerable to more and more intense hurricanes. Global warming also increases wildfires and droughts. California residents have recently been devastated by wildfires and as long as global warming is still increasing, there will be more and more vulnerable people in these areas.

Assume that you are asked to be a part of a Tornado Chase team for the month of May. Based only on your knowledge of tornado climatology in the US, what states would you begin your work?

I would begin my work in Oklahoma and the prairie states. This is because tornadoes are most likely to occur here in tornado alley as a result of warm moist air from the Gulf clashing with the Northern cool air from the north. In May I would expect to see tornadoes in this area such as Oklahoma.

Would you expect to see more tornadoes in Vancouver, BC or Edmonton, Alberta? Why?

I would expect to see more tornadoes in Alberta because this is a prairie province and tornado alley includes this location. This is due to the fact that the Rocky Mountains block Vancouver from receiving the warm moist air from the Gulf of Mexico. The warm moist air from the gulf is more likely to clash with the cold air from the north in Alberta.

Assume that you are asked to be a part of tornado chase team for the prairie provinces of Canada. What month would you expect to be most successful. Explain

I would expect to see most tornadoes in this area in the month of June due to the air being warmest during this time of the summer. Warm moist air is a necessity in the formation of severe thunderstorms and tornadoes, therefore a tornado chase would be most successful in the month of July for the Canadian prairie provinces.

You are a reinsurance industry executive and are therefore responsible for estimating future losses associated with natural disasters worldwide. Specify at least two of the most important factors that you use as input to your estimate.

I would look at location. 1, make sure to take into account vulnerable areas such as the coast and in subduction zones that are highly prone to natural disasters. 2, I would take into account the population and building structures to estimate what could withstand ex. hurricane or earthquake.

Assume that your job is to prepare Montreal for future major ice storms. Name 2 of your most important tasks in this preparation during the autumn months. Explain your reasoning.

I would tell people to have a plan in place, keep a safety kit of flashlights and batteries in case of power outages and to have a secondary source of power/heat to keep warm. I would also make sure that the city has set up sufficient shelters with back up heat in order to help people stay alive.

Compare the atmospheric stabilities that are associated with an ice storm, and with a tornado outbreak.

Ice storms have an extremely stable atmosphere, so much so that there can be an inversion of lapse rate. The atmosphere is extremely unstable during a tornado outbreak.

Stratovolcanoes commonly erupt violently for short periods of time. If the magma chamber beneath a stratovolcano is large, the eruption may continue for an extended period of time, causing the magma chamber to drain. Discuss the possible consequences to this.

If the magma chamber drains and the force of the roof cannot stay in tact, it will collapse, causing a caldera to form. This can affect the size and intensity of the eruption.

Which ocean basin is more vulnerable to tsunamis, the Indian ocean or the Pacific ocean? Justify your answer.

In the Pacific ocean because this is a subduction zone, which means that volcanoes, earthquakes, and landslides are typical here. These events can offset and trigger a tsunami based on the displacement of the ocean floor in the subduction zones of the Pacific Ocean.

El Niño is a phenomenon which can have radically different effects on weather based on your location in the world. For example, it is often associated with rainfall increase along the west coast of South America in Peru, and drought in Australia. Using your knowledge of how El Niño works, provide an explanation for why this may be.

It affects weather differently in different areas because of the trade winds and their reversal in directions. During an el nino, the trade winds that typically bring warm ocean temperatures to the west, will likely be reversed, bringing the warm ocean temperatures to the East, along the coast of South America. As a result of this warmer ocean temperature, there is much more convection and condensation bringing in clouds and heavy rainfall in these areas. In contrast, during an El Nino in Australia it is typical to see a drought and reduced rainfall due to the warmer ocean waters being shifted East and therefore colder ocean temperatures in Australia don't produce much condensation and thus rainfall.

Is it possible to have a thunderstorm occur in the city of Montreal during the month of December? Why or why not?

It is highly unlikely given that the temperature is much colder, therefore much drier. A necessary condition for thunderstorms is warm moist air. There are snow storms that can occur in December though, but no thunderstorms.

A well-known political figure recently sent the following tweet regarding the recent cold spell along the east coast of the United States: "Brutal and extended cold blast could shatter ALL RECORDS - whatever happened to global warming?" Formulate a response to this tweet.

My response would be: While it was particularly cold along the Eastern part of the US this fall and winter, the global trend actually shows otherwise. You cannot just look at a specific region to dismiss global warming, and when we look at the temperatures globally, we see that there is a dominance of unusually warm temperatures. Many things such as an el nino or la nina and other factors can affect the weather and temperatures in a specific region, but globally there is a clear indisputable trend and this is globally the 2nd warmest October since we have begun to take records. And 2. you have to look at trends over time not one specific time

Would you rather try escaping from an advancing lava flow or from an advancing pyroclastic flow which is coming towards you? Explain

Lava flow because they are slow and you can generally outrun them but pyroclastic flows move too fast and you would die.

In a divergent boundary volcano, what type of magma would you expect to see?

Magma as basaltic lava flows such as the Erta Ale in Ethiopia

Compare earthquake vulnerability in San Francisco today compared to 100 years ago.

More recent buildings are much better at withstanding the shocks of an earthquake. A century ago, this was not the case, therefore they were highly vulnerable 100 years ago. However, there was less population 100 years ago in San Fransisco and now more people are at risk. We still today can't predict earthquakes well.

Discuss how recent population movements into more urbanized areas have changed society's vulnerability to future natural disasters.

Populations have increased in very vulnerable areas, such as the coast in Florida which is prone to hurricanes, or in California which is prone to wildfires. Many people build houses in vulnerable areas and therefore the increasing population in these areas can have a huge impact on the amount of damage and death that can occur when there is a natural disaster.

Discuss the hazards of pyroclastic flows.

Pyroclastic flows are usually very fast and extremely hot. Buildings can be burnt down and destroyed by the force and temperature. The greatest hazard is close to the volcano in depressions such as river valleys.

Why do shield volcanoes have gentle slopes compared to stratovolcanoes having steep slopes?

Shield volcanoes are composed of low-viscosity basaltic lava flows, creating gentle slopes. In contrast, stratovolcanoes are constructed from higher viscosity andesitic lava flows from pyroclastic rocks which stacks up creating a steeper slope.

Both cinder cones and shield volcanoes erupt mainly basaltic lava, yet their forms and sizes are very different. Discuss these differences.

Shield volcanoes have mainly basaltic lava flows, creating much gentler sloping angles. Cinder cone volcanoes have steeper, straighter sides due to pyroclastic materials.

Are shield volcanoes or stratovolcanoes more prone to sector collapse? Explain

Stratovolcanoes are more prone to collapse due to its steeper form, as a result of high viscosity andesitic lava flows and low-strength pyroclastic materials.

Along what time of plate tectonic boundary do the largest and most destructive earthquakes occur? Explain

Subduction zones along convergent boundaries. This is due to a huge amount of stress created as a the oceanic plate slides underneath the continental plate.

Discuss how you would be able to distinguish a tropical storm from a hurricane using only satellite images.

The difference using satellite images would be that a clear eye is present in that of a hurricane. Whereas it is not in a tropical storm.

What geographical region in Canada is most vulnerable to tornadoes? Explain

The prairie provinces such as Manitoba, Saskatchewan, and Alberta, and Southern Ontario. This is due to warmer air from the gulf clashing with the cold air from the north in these regions, as they're generally much flatter.

Briefly discuss how warm water serves as the energy source for tropical cyclones.

The reason warm water is the energy source is due to latent heat release. Warmer water produces evaporation and thus water vapor. The water vapor condenses and releases energy into the atmosphere.

As a tsunami approaches the shoreline, the wave experiences certain changes. Describe and explain these changes.

The wave characteristics as it approaches the shoreline will depend on many factors, such as if the crest or trough of the wave arrives first. If the trough reaches the coast first then there will be drawdown, which is characterized by the water along the shoreline drawing back before the 1st crest of the wave arrives. The height of the wave is usually highest right before it breaks before it reaches the shoreline.

During a significant El Nino event, would you expect to see more or less hurricane activity in the Atlantic Ocean? Explain.

There would be less hurricane activity, due to there being too much wind shear.

What role does the Atlantic Ocean's Azores High play in the movement of Atlantic hurricanes?

They move from East to west because of the Azores High

There has been a significant increase in tornadoes over the past 100 years. Why?

This is due to climate change. Climate change increases global temperature, causing more warm air, which increases the likelihood of tornado formation.

When tsunamis strike coastlines, some people suggest they behave more like floods than waves. Discuss this reasoning.

This is due to the breaking of the wave that can occur sometimes right before it reaches the shoreline due to the height of the wave being highest. Therefore, it may seem like it's just flooding if the wave has already broken before it reaches the shore.

Define 'supercooled' water. How does this phenomenon relate to an ice storm?

This is liquid water that exists at temperatures below 0 degrees C. Supercooled water not not become ice because ice crystals need something to grow on, and supercooled water is too pure. An ice storm consists of liquid water existing at this temperature as supercooled water, which freezes upon impact.

What is the maximum amount of time you would expect to see during a tornado warning? Explain why

Tornado warnings are issued when the conditions for a localized demonstrate the ideal conditions for tornado formation. This includes moisture, instability, wind shear, and a lift mechanism. Therefore I would expect the maximum time for a tornado warning to be about an hour, since conditions can change very rapidly.

Where do thrust faults occur?

Transform boundaries; earthquakes are shallow and powerful

Earthquakes can trigger other naturally-occurring hazardous phenomena. Discuss two examples.

Tsunamis and landslides. Tsunamis need a trigger and an earthquake of M9 means a tsunami is inevitable. Landslides created by a shift along the fault zone and is especially common in mountainous areas. The shaking of the earthquakes can trigger landslides.

Explain the tsunami hazard posed by oceanic volcanic islands such as Hawaii and the Canaries.

Tsunamis can be triggered by volcanic activity that displaces ocean floor generating tsunami waves. Therefore, islands that are located in subduction zones that have more volcanic activity are in a more vulnerable position in terms of tsunamis. Pyroclastic flows in the water, submarine caldera collapse, or any type of displacement due to volcanic activity can trigger a tsunami.

List 4 causes of tsunami waves with an example for each.

Tsunamis need a trigger. Some examples of this may be, volcanic activity, landslides, meteor impacts, or earthquakes. These events can displace and cause an offset of the ocean floor which can trigger a tsunami.

Assume that you have been asked to provide a forecast of precipitation type for the next day in Montreal. What information do you need in order to determine whether the event will be rain, snow, or freezing rain? Explain your reasoning.

You would need to know lapse rates to determine stability to determine if there is an inverse in lapse rate because in ice storms the air is so stable that this is usually the case. You'd need to know the temperature of the atmosphere to determine if there is a deep warm layer in between two shallow cold layers

Explain what is meant by 100 year flood.

a recurrence interval of 100 years.

Earthquakes and eruptions both occur along mid-ocean ridges. Explain a. the types of faults which generate these earthquakes and b. the composition of lava produced by these eruptions.

a. normal faults are produced by stress as the two oceanic plates move apart b. the lava would be basaltic in composition (50% SiO2)

Why are basaltic lavas runny and rhyolitic sticky?

a. the silica content is lower in basalt than rhyolite. b. basaltic lavas are hotter than rhyolitic lavas

Where do reverse faults occur?

convergent boundaries; earthquakes are deep and also powerful

Where do normal faults occur?

divergent boundaries; earthquakes tend to be weak and shallow

What technology has allowed for the increase in tornado warning times?

doppler radars can give an indication of speed and direction. Satellite imaging can give us a broader sense of the conditions while doppler radars can tell us the speed and direction that a tornado is heading.

Among the various hazards associated with hurricanes, which is the most significant contributor to loss of life?

inland or coastal storm surges

Discuss the hazards of pyroclastic ash falls.

roof collapses on people and harder to breathe.