Natural Disasters Exam #2 STUDY GUIDE QUESTIONS (University of Iowa Spring 2020)

You should be familiar with the "good" and the "bad" of wildfires.

"Goods and Bads" of Wildfires: Good: - Wildfires can allow some plants to release seeds and leave important nutrients in the soil for plants in the next growing season - After a wildfire, the forest is regenerated and can improve the overall health to the ecosystem - Supports successional communities and forest health Bad: - Property destruction and fatalities - Increased debris flows and flood hazard (devegetation, hydrophobic soils) - Release of soot/ash/aerosols - Hydrophobic soils (bad): - When wildfires burns happen they create hydrocarbon and waxy residues (think about petroleum jelly) that leach into soils and make the soil impervious to water (doesn't allow water to be absorbed into the soils) - Increases runoff during rain and potential mass wasting events like shallow debris flows - Encourages the downward movement of moisture and contributes to erosion

What percentage of the Forest Service budget goes towards fighting fires?

- 50% of the USFS budget goes towards fighting fires that have started, this doesn't even account for fire management - More than $3 billion dollars per year

How are rhyolites generated?

- Continental crust with mantle beneath - if you generate basalt and put that at the bottom of the crust - transfer heat and the crust melts - low temperature melts are rhyolites

What conditions do we need in the atmosphere during the early stages of hurricane for for them to develop?

- Differences in pressure zones (warm in the middle cold on the outside) - Convection going on in the RING

Why shouldn't you fly an airplane through an ash cloud (what can ash do to a plane engine? What can it do to other parts of the airplane?

- Engine: ash deposits melt and clog interior, blocking fuel nozzles and restricting airflow, resulting in lost of thrust or failure - Corrosion - The pilot can't see - Ash blocks pilot tube used to measure airspeed

We discussed the addition of gases and their impacts on the explosiveness of eruptions. How do gases drive explosive eruptions, and what does it mean for a rock to be vesicular? How does this also relate to viscosity (given the same gas content, would a fluid lava or a viscous lava produce a more violent eruption)

- Expansion of gases bring the magma closer to the surface - When magmas start rising, they exsolve (release) the gases and form bubbles called vesicles. The presence of the vesicles increases the volume and viscosity of the magma. This all causes the pressure to build up and leads to explosive eruptions - Dissolved gases exsolve when magmas rise to lower pressure - Bubble growth results from gas loss, which dramatically increases volume of magma and raises viscosity (removes water from the magma which causes viscosity to increase and makes magma more pasty increasing the volume) (this magma approaches the surface and can't flow so it just explodes) - Vesicular rocks have bubbles in them - Fluid lava produces a less violent eruption than viscous lava because the gas bubbles can escape from the magma more easily

What kinds of eruptions characterize composite volcanoes? Know the anatomy of composite volcanoes.

- Explosive and effusive eruptions - Steep sides - Andesite or dacite

How do pyroclastic fall (or fallout) deposits differ from pyroclastic flow deposits? Where do surge deposits fit in? How do these different events compare to each other, in terms of behavior and density?

- Fall deposits are sorted - Flows deposits are unsorted - Surge deposits are in between sorted and unsorted - Fallout erupts and rains out material - Flows are full of gases and water and act like a fluid - Surges are explosive and have a much higher gas content than flows

What type of eruption is associated with fire fountains? How about bubble pops and short-term vigorous explosions?

- Fire Fountains = Hawaiian - Bubble Pops = Strombolian - Short-term vigorous explosions = Vulcanian

Why do we see a lot of hurricanes forming in association with ITCZ, and what is the ITCZ?

- Intertropical Convergence Zone - two trade winds are going counter each other when they meet they have 2 temps and directions and that helps form hurricane

Why don't hurricanes form at the equator?

- Observations show that no hurricanes form within 5 degrees latitude of the equator. People argue that the Coriolis force is too weak there to get air to rotate around a low pressure rather than flow from high to low pressure, which it does initially. - Also, Inter Tropical Convergence Zone

How deadly are volcanoes, relative to the other hazards we have discussed this semester? Compare recent and past histories.

- Other natural disasters cause way more deaths than volcanoes - "only" 363 fatalities from 2004-2013 - Since 1600, there have been 260,000 deaths due to volcanic eruptions - 5 particular events that caused the bulk of the fatalities: Unzen, Tambora, Krakatau, Pelée, and Nevado del Ruiz - Earthquakes and tsunamis: 650,321 deaths - Floods/Meteorological/climate: 328,580 deaths - Landslides/mudflows: 9,012 deaths

How does silica content modify viscosity, and why? Which type of magma would be more viscous, basalt or rhyolite, and why?

- The higher the silicon dioxide (SiO2) content of a magma, the more polymerized the melt, increasing molecule size, internal friction, and viscosity - Rhyolite is more viscous than basalt because it has a higher silica content

Know the effects temperature, silica content, and water content have in the viscosity of magmas. How are these magma characteristics reflected in volcanic landforms, and how does this all relate to plate tectonic setting?

- The more water you add the more you break apart molecules and decrease viscosity - The more silica content (SiO2) in magma the more polymerized the melt, increasing the molecule size and "internal friction", and thus, increasing viscosity

How does the addition of water to magma modify its viscosity?

- The more water you add, the more you break apart these molecules and decrease viscosity - Thus, the more water, the less polymerization

What kind of reaction occurs during a fire? You should know both that this is an example of oxidation (and requires oxygen) and also that it is exothermic.

- rapid, high temperature oxidation reaction (combustion) release heat, light and other products - combustion results in fast break down of organic materials - exothermic

Name and understand the 5 (or 6?) methods scientists use to monitor volcanoes.

1. Ground Vibration: - Network of seismic stations to monitor seismicity 2. Ground Deformation: - Look for visual changes in the volcano edifice - Infrared cameras can see large spikes in temperature of the ground 3. Gas: - Monitor for large changes in the rate of volcanic gas emission (i.e. carbon dioxide, sulfur dioxide, carbon monoxide, hydrofluoric acid) - Gas monitoring is achieved by having planes with sensors drive through gas clouds to look at changes in the solar ultraviolet light to identify the gases present 4. Seismicity: - Brittle rock failure - Cracks resonate as magma and or gases move toward the surface - Failure + magma or gas movement - Magma movement or slow-slip earthquakes - Resonance due to extended flow of magma movement through cracks - As magma is moving through the surface, there are small earthquakes generated by the movement - Tremors can last for days or weeks and is caused by magma moving through cracks, very commonly associated with eruptions 5. Geodesy: - inSAR (interferometric synthetic aperture radar): Phase shift for radar wave caused by ground movement - inSAR is a technique that uses satellites to image phase shifts caused by ground movement - Continuous GPS can also be used to look for ground movement 6. Lightning: - World-wide network of monitors that look for lightning since many volcanic eruptions generate lightning

2 locations were discussed that are significantly imperiled by volcanoes? What are these locations and which volcanoes pose hazards for these locations?

1. Naples and Vesuvius: - Naples, Italy, with a population of 4 million people, is in danger of eruptions from the Campi Flegrei caldera system and Vesuvius - The 79 AD eruption of Vesuvius is infamous for the destruction of Pompeii and Herculaneum 2. San Salvador, El Salvador: - The capital of El Salvador, San Salvador, has a population of ~2.4M people and sits between 2 volcanoes - Ilopango and Boqueron - City was built on top of pyroclastic flow deposits

Be familiar with the specific examples of different particular volcanoes that we discussed (e.g. Nyiragongo, Mt. Vesuvius, etc.).

1. Nyiragongo: - people died from fast moving lava flows - The town of Goma in the D.R. Congo is at risk of lava flows from the volcano Nyiragongo Eruptions of Nyiragongo: - The latest eruption occured in 2002 - Fracture opened on the volcano flanks between 2800 and 1700m elevation resulting in the eruption of 20-30 million cubic meters of lava - Traveled up to 60 mph - 15% of Goma destroyed approx 10,000 homes and 400,000 people displaced - The side of the volcano broke apart and there were very fast-moving lava flows that destroyed ~15% of the town - The lava at this volcano is especially non-viscous so it was able to travel very fast - 147 people were killed by CO2, asphyxiation, fires, and building collapse associated with earthquakes

Approximately the various volcano hazards and which ones have had the most impact over the past 500 years?

1. Pyroclastic flows and surges are the most deadly volcanic hazards 2. Tsunamis 3. Lahars 4. Indirect fatalities (like famine) are nearly as deadly as pyroclastic flows 5. Causes of volcano fatalities (280,000) since 1500 AD

What ingredients do we need for a hurricane to form? Because of these ingredients,where and when do hurricanes form?

1. Warm ocean water 2. high wind shear 3. >5 degree latitude. - Occur most during June-Late november(hurricane season) peaks at september

Know the names and nature of the disasters caused by the two major hurricanes we discussed and that hit the USA in 2017

2 Major Hurricanes in 2017: - 1. Hurricane Maria (2017): - September 16th-October 2nd, 2017 - Category 5 at its peak - This hurricane increased strength extremely fast and hit puerto rico as a category 4 - Puerto Rico was completely devastated Highest Winds: 175mph (280 km/hr) Lowest Pressure: 908 mbar (hPa); 26.81 in Hg Fatalities: 2,975 Damage: >$91.61 Billion (USD) - 2. Hurricane Harvey (2017): - Intense rainfall caused widespread flooding and was especially devastating for Houston, Texas - Hit the coastline as a category 4 hurricane but then stalled dumping a lot of rain in the process - Up to 60 inches of rain Highest Winds: 130 mph (category 4) Lowest Pressure: 937 mbar (hPa); 27.67 in Hg Fatalities: 69 direct, 39 indirect Damage: $125 Billion (USD) - 2nd most expensive tropical cyclone after hurricane Katrina 2017 Atlantic Hurricane Season: - In September, there were 5 major hurricanes, 2 were category 5 - $200 Billion in damage (USD) What Made 2017 So Bad? 1. Warm water 2. Low wind shear 3. Storms steered directly into population centers: - Houston, Texas - East Florida - Puerto Rico

What are the three legs of the fire triangle? Of the fire behavior triangle?

3 Legs of the Fire Triangle: 1. Fuel: Combustible substance 2. Heat: Temperature high enough to cause combustion 3. Oxygen: Enough oxygen to sustain combustion 3 Legs of the Fire Behavior Triangle: (Topography, Weather, Fuel) 1. Topography: (Terrain, Hillslope Aspect, and Elevation) - Fires on a flat surface conduct heat to the ground, convect heat to the atmosphere, and radiate heat outwards - When the fire is on a slope the material uphill of the adjacent fire is preheated uphill -----> This is why fires tend to spread uphill. Hillslope Aspect: The direction (North, South, East, or West) a hillslope faces - North facing slopes (in the Northern hemisphere) are more vegetated and wetter - In the U.S. the sun faces more on south-facing slopes which means that north-facing slopes are less likely to burn and are able to maintain moisture and stay vegetated 2. Weather: (Winds, Temperature, and Humidity) - Warm temperatures + low humidity + stronger winds = increased potential of wildfire danger - "Red Flag Warnings" are put out by the weather center when the conditions for wildfires are favorable due to warm temps, low humidity, and strong winds Winds: Wind pushes the fire and changes the direction of heat flow - The surface adjacent to the wildfire in the direction of the wind is preheated 3. Fuels: (Fuel Type, Fuel Moisture, and Fuel Temperature) - Fuels are the things that burn Types of Fuels: 1. Surface and Ground Fuels: - Sticks, grasses, shrubs, mosses in the soil 2. Ladder Fuels: - Trunks of trees, sticks or branches growing out of the trees, vines - These help fires grow vertically 3. Crown Fuels: - Canopies of trees

What criteria are mass wasting events classified upon?

3 Things Classification of Mass Wasting Events are Based On: 1. How materials move 2. Type of material moving 3. Rate of movement

What determines eruption style and type of volcano formed?

3 Things that Determine Eruption Style of a Volcano: - 1. Viscosity - 2. Gas content - 3. Volume of erupted material - Different types of lava have varying physical and chemical properties which leads to different styles of eruption - A lot of the characteristics of a volcano come down to the tectonic setting where the volcano forms

What are examples of flows, and how are they differentiated from each other?

3 Types of flows: 1. Debris Flows: - Involves the presence of rocks with mud in between the particles - Fluid movement of rock fragments supported by a muddy matrix (less than 50% fine grained material) - Tends to flow rapidly, up to 100 km/hr - Mudflows are just very wet debris flows 2. Lahars: - Debris/mud flows originating on volcanoes - Basically volcanic mudflows that form when loose material mixes with water and flow down steep topography - Move very fast - Involve a lot of fluid 3. Avalanches: - Very fast flow where the fluid is air - May include debris, rock, soil, snow, or ice

What are the three different ways by which we can generate melt? Which of these processes occurs at a mid ocean ridge or associated with a mantle plume?

3 ways of generating melt: 1. Decompression Melting: Melting by lowering pressure - Melting at ridges like the mid ocean ridge/mid Atlantic ridge and Iceland - Mantle plumes 2. Flux Melting: Decreasing the melting point of rock by adding fluids - Water from the subducting slab is added to the overriding mantle. This lowers the melting point of the rock and generates magma - Subduction related 3. Heat-Transfer Melting: Adding heat to already hot rocks - When you add very hot magma (like basalt) to the continental crust, the crust starts melting and generates rhyolitic volcanism - Not specific to any type of tectonic setting

Approximately how many on-land volcanoes are presently erupting?

40

What are common strategies for mitigating mass wasting, and how do these strategiescounteract the causes of mass wasting?

5 Ways of Preventing Mass Wasting: 1. Hazard Mapping and Zoning Restrictions: - Make it so people can't build certain types of buildings or at all in high risk areas 2. Revegetation: - Adding vegetation to increase slope strength 3. Regrading: - Stabilize slopes by making slope more gradual 4. Reinforcement: - Adding rocks, bolts, rock nets, etc. to increase slope strength 5. Improve Drainage: - Change hydrology to decrease pore pressure

Why is Mount Rainer so dangerous?

5 major reasons Mount Rainer is so dangerous: 1. It is an extremely populated area: - More than 300,000 people now live in the area covered by these lahars 2. Lots of lahars: - There have been at least 50 lahars in the past 10,000 years, including the largest lahar deposit ever found 3. Covered in glaciers: - Probably the most hazardous volcano in the U.S. because it is very large, steep sided, and covered in glaciers 4. Has lots of volcanic gases: - Can have local to global scale effects ---> Local: suffocation and lung damage ---> Global: climate change - Volcanic gases are unhealthy for the local population to breathe in and can cause changes to the global climate if there are enough gases released 5. Steep sided

Know the terminology describing the anatomy of a landslide

Anatomy of a Landslide: - Crown: Top of the slide - Head Scarp: In front of the crown, vertical wall left at the top of the slide - Slump blocks: Coherent blocks that fall and move in the slide - Fissure: Cracks that form as the material breaks away and resettles - Toe: Leading edge of the slide - Main body: Region that constitutes the majority of the material in the slide

What are the two caldera systems we discussed in Indonesia? Be able to characterize their VEI, volumes, ages etc.

Caldera: - A large basin-like depression that is many times larger than a volcanic vent - In terms of destructive potential of various types of volcanoes, calderas are by far the biggest threat - Least likely to occur - Yellowstone National Park is centered on a massive caldera Supervolcanoes: - Small historic example: Tambora, Indonesia - Large examples: Yellowstone and Toba, Indonesia 2 Caldera systems in Indonesia: 1. Tambora, Indonesia: (small historic example) - Greatest historic eruption: April 5th-11th, 1815 - VEI 6-7 - Est. 50-100 km3 of lava erupted (without bubbles) - Eruption column 44km high (144,000 ft) - Lost 1450m (4700 ft) of elevation - 80-90,000 dead in local area, about 11,000 directly, and more secondary deaths from famine and disease - Locally, upwards of 50cm of ash was deposited - If the same eruption were to happen today millions of people would be severely impacted 2. Toba, Indonesia: (large historic example) - VEI 8 eruption - 74,000 years ago erupted 2,800 km3 of material - Toba's caldera is 100km across compared to the 7km caldera produced by the 1815 Tambora eruption

Be able to recognize the characteristics of cinder cone volcanoes vs. composite/stratovolcanoes vs. shield volcanoes. You should also know the relative sizes of these landforms.

Cinder Cones: A conical-shaped hill created by the build up of cinders (lapilli) and other pyroclastic material around a vent - Particles erupted explosively and come to rest at angle of repose (35 degrees unconsolidated debris stability) - Short-lived and easily eroded - Typically basaltic - Basically large piles of pyroclastic material that have bubble pop eruptions - Constant slope where particles come to rest at an angle of repose of 35 degrees - Don't last very long in the geologic record Composite/Stratovolcanoes: A volcano that forms from alternating layers of lava and pyroclastic debris - Most widely recognized volcano shape - 2nd in size behind shield volcanoes - Erupts lava flows and explosive pyroclastic material - Relatively steep sides Examples: Mt. Shasta, Mt. Fuji, Vesuvius - Capable of explosive and effusive eruptions - Typically high viscosity magmas like andesite or dacite - Volcano is built up by both explosive eruptions and lava flows (eruption style dependent on gas content, temperature, and viscosity) Shield Volcanoes: A broad volcano that has gentle slopes consisting of low viscosity basaltic lava flows - Largest volcano in size - Significantly larger than cinder cone volcanoes with a broad edifice created by many lava flows over time - Basaltic lavas erupt out of vent or fissure zones - Examples: Mauna Loa is the biggest volcano on Earth and is a shield volcano, Hualalai is another Hawaiian shield volcano with several cinder cones along edifice - Eruptions associated with shield volcanoes are quiet and move across the surface from 1-10 meters an hour

Why do hurricanes rotate, and which way do they rotate in the different hemispheres?

Coriolis Effect: - Regulates wind speed and direction - Rotation of the Earth is strongest at the equator and weakens at higher latitudes which causes wind to bend in different directions depending on which hemisphere you are in - Wind in the northern hemisphere is bent to the right (counter-clockwise) while the wind in the southern hemisphere is bent to the left (clockwise)

What are some examples of creep and/or slow-moving mass wasting events?

Creep/Slow Moving Mass Wasting Events Examples: - Slums - Slow moving landslides - Leaning fence posts - Drunken trees

What is creep (in terms of mass wasting), and what is the primary process that causesit?

Creep: Slow, continuous movement of materials downslope by expansion and contraction of clay-rich soils, frequently related to freeze-thaw cycles Freezing: - Soil particles moves up perpendicular to the slope Thawing: (contraction) - Creep is supported by the freezing and unthawing of water in the pore spaces of rocks and soils

How do we define cyclonic storms?

Cyclonic Storms: - Defined by low central atmosphere pressure and inwardly rotating winds

What is a debris avalanche? What are the characteristic of a debris avalanche deposit?

Debris Avalanche: - Debris avalanches are large, extremely rapid flows formed when an unstable slope collapses and the resulting debris is rapidly transported away from the slope Examples: 1. Mount St. Helens: - was the first time geologists were really able to study and understand debris avalanches due to volcanic eruptions 2. Mount Shasta: - One of the largest landslides triggered by volcanic activity is a debris avalanche formed about 300,000 years ago in northern California - Cause was a major eruption - Not recognized as a landslide until after the 1980 eruption of Mount St. Helens, which resulted in similar, but smaller disruption of Earth's surface

What happened when the Deccan Traps were erupted? What major evolutionary event is it associated with? How could eruption of a volcanic province like this impact global climate and global ecosystems?

Deccan Traps: Largest basalt flows on earth caused by a hot spot, possibly contributed to the mass extinction at the end of the cretaceous - India and Seychelles Plateau 65 million years ago - 1,300,000 km3 of basalt - Extraordinary large amounts of basalt eruptions in less than 1 million years - A single lava flow can be traced for 1,000 km (distance from Iowa City to Pittsburgh) Effect on Climate: - Decades long periods with 10x the amount of CO2 and SO2 released each year compared with the Laki eruption - Series of eruptions led to an immense amount of gas released with evidence for ocean acidification and global warming - Likely placed a role in the extinction of the dinosaurs 65 million years ago - Chicxulub meteor impact was the final blow, but the extinctions likely began with deccan traps

What are erosion and weathering, how are they different from each other, and how do they contribute to mass wasting?

Erosion: - Geologic process that removes and transports Earth materials to a new location - All mass wasting events are erosional events, BUT not all erosional events are mass wasting events Erosion Examples: Rivers undercutting banks (stream erosion), waves moving sand and dunes (coastal erosion), glaciers carving fjords (glacial erosion) Weathering: - The geologic process of physically or chemically breaking down or changing earth's materials - Mass wasting events do not require weathering, BUT weathering creates erodible material that eventually moves in a mass wasting event - Doesn't transport materials Weathering examples: Rocks cracking during freeze-thaw, rust formation, cave formation, through dissolution of limestone

What are the different parts of an eruption column (anatomy)?

Eruption Column: 1. Gas thrust region 2. Convective thrust 3. Umbrella region, downwind plume, and fallout

What type of eruption (from the above) is associated with eruption columns and pyroclastic flows?

Eruption columns and pyroclastic flows = Plinian

You should know the relative ranks, in terms of the VEI, of Hawaiian, Strombolian, Vulcanian, Plinian, and Ultra-Plinian eruptions. It might be helpful to think of a mnemonic device here.

Eruption styles ranking: (least to most explosive): Hawaiian (least explosive): VEI 0-1 - Iceland - Fire fountains feeding lava flows Strombolian: VEI 1-2 - Anak Krakatau, Stromboli - Bubble pops - gases accumulate then pop like a bubble - brief spurts of explosive but not very vigorous activity Vulcanian: VEI 2-4 - Papua New Guinea - periods of vigorous explosions Plinian: VEI 4-6 - Eyjafjallajökull in Iceland - Calbuco volcano in Chile - sustained explosive eruptions that produce an eruption column and sometimes pyroclastic flows Ultraplinian (most explosive): VEI 7-8

How are fires classified, and how do they start?

Fire Classification: - Defined by the layer of fuel burning 3 Types of Fuels: 1. Surface and Ground Fuels: - Sticks, grasses, shrubs, mosses in the soil 2. Ladder Fuels: - Trunks of trees, sticks or branches growing out of the trees, vines - These help fires grow vertically 3. Crown Fuels: - Canopies of trees 3 Fire Types: 1. Ground Fires: - Burning in the subsurface (organics in soil, mostly smoldering combustion) - Material that smolders through combustion under the ground - Caused by ground fuels 2. Surface Fires: - Burning on ground surface - Grasses and shrubs are burning at the ground surface - Tend to move laterally - Move rapidly - Caused by surface fuels 3. Crown Fires: - Burning in the crown of trees - These tend to be the most difficult to control because they're the most intense - Caused by crown fuels

What are flows, and how are they differentiated from slides or creep-related mass wasting?

Flows: - Material moves and behaves like a fluid. Speed is variable and particles move relative to each other - Fluid slurries of loose rock, mud, and other materials. - This includes avalanches, debris flows, or mud flows depending on the amount of water vs. solid material being moved - Are controlled by the presence of fluids and cause the material to move very rapidly - Fluid is usually water but it can also be air in the case of avalanches Slides: - Material moves along a well defined plane as a coherent mass - Slides can turn into flows if water is added and there is a loss of sediment cohesion Differentiation of Flows and Slides: - Flows are very fast as compared to creep-related mass wasting events

What sort of hazard does volcanic ash pose to you, especially if you live close to an active explosive volcano?

Hazard: Ash Clouds: - Can erupt blocks and bombs - Ash can act as an irritant to the eyes and lungs (very bad for your respiratory system) - Can damage airplanes, vehicles, and houses - Contaminate water supplies - Kill/damage crops and livestock

What hydrological factors influence hillslope stability, and why?

Hillslope hydrology: - Some water increases cohesion (surface tension holding grains together) - Too much water forces grains apart (loss of frictional contact Sandcastle example: - You need a little bit of water to build your sandcastle, but if you add too much water, the sandcastle falls apart

What is a hillslope? How do hillslope shapes vary according to the materials they are made out of?

Hillslope: - Sloped sides of topography, often terminating in a river or glacial valley - Required for most mass wasting events because they create the gravitational requirements for materials to move downward

How do fires transfer energy? Be able to match terms and definitions here.

How Do Fires Transfer Energy? 1. Conduction: - Heat passes through fuels, driving off moisture and preparing it for burning - Conduction drives off moisture and makes more fuel available by drying it out 2. Convection: - Heated air and gases rise above burning fuels, transferring heat vertically from the ground into the atmosphere (canopies) and generating wind (oxygen source) - Hot air is buoyant and rises - This process also circulates air and generates wind; thus, bringing more oxygen into the system and sustains the wildfire 3. Radiation: - Heat radiated from a flaming front moves the fire laterally and preheats other fuels that are adjacent to the fuel fire Stages of Combustion in Wildfires: Phase 1: Pre-heating/Pre-ignition: - Fuels ahead of fire are pre-heated by convection and radiation, thereby dehydrating them and preparing them to burn - Volatiles are released and evaporate into gas phase - This phase occurs relatively rapidly - Pyrolysis occurs: This is the chemical changes the fuels undergo prior to ignition - Turn into charcoals, 325 degrees celsius - Charcoal material smolders until all of those gases are burnt off as well - Phase 2: Ignition Phase (Gas): - Volatiles generated in phase 1 through evaporation and pyrolysis are ignited and oxidize to form flames - Formation of flames - Flaming combustion reactions continue until the volatile gases burn off - Exothermic reactions happen at 200-1000 degrees celsius in wildfires - This is an exothermic reaction that releases heat as the chemical bonds breakdown (chemical bond energy is released)

How do we generate melt at subduction zones?

How do we generate melt at subduction zones?: - Fluid Flux Melting: Decreasing the melting point of rock by adding fluids - Water from the subducting slab is added to the overriding mantle. This lowers the melting point of the rock and generates magma - Subduction related -when the mantle melts, it turns into magma

How do humans modify each leg of the fire behavior triangle?

Human Modification: We have the ability to modify every aspect of the wildfire triangle Fuel: Forestry management practices of preventing fires have led to fewer, but more intense fires - Forests weren't allowed to burn so there weren't smaller fires to remove surface and ground fuels Topography: People are increasingly moving into regions that were once forests so communities are now residing in areas prone to wildfires Weather: Climate change is causing higher temperatures and less precipitation - This has caused longer wildfire seasons in regions like the Amazon, western US, and eastern Africa - Fire season in the US in now 78 days longer than in 1970 - Shifting temperature patterns has also created new insects threats - Migrating insects are killing trees and creating new fuel

What major hurricane that hit the Bahamas in 2019?

Hurricane Dorian (2019): - August 24th-September 10th, 2019 - Most intense Atlantic hurricane - Category 5: 185 mph (gusts to 220) - Lowest Pressure: 910 mbar - Moved slowly (< 5 mph) when peaked over Bahamas - Produced a very large 23 ft storm surge - More than 24 inches of rain - Fatalities: 84 - Damage: $4.6 Billion (USD)

Where did Hurricane Mitch strike? Why was it so deadly?

Hurricane Mitch (1998): Struck 2 locations 1. Nicaragua: - Stalled offshore of Nicaragua as a category 5, but weakened before making landfall - Displaced population: 368,300 - Refugees: 65,300 - Refugee centers: 304 - Deaths: 2,860 (mostly due to landslides generated by heavy rainfall) - Houses damaged: 17,600 - Houses destroyed: 23,900 Hurricane Mitch (1998): 2. Honduras: - 36.5 inches of rain recorded in Choluteca - 12 inches of rain recorded in Tegucigalpa - (unofficial total of 75 inches of rain) - Flooding and landslides: (including in the largest city, Tegucigalpa) - 1.5 million people homeless - Damage: $3.8 billion (70% of crops destroyed) - Fatalities: 7,000-15,000 deaths

What is a lahar?

Lahar: Unconsolidated material + steep topography + water = Severe Hazard! - A volcanic mudflow or landslide that contains unconsolidated pyroclastic material - They are basically volcanic mudflows that form when loose material mixes with water and flow down steep topography - Generally occurs near composite volcanoes (Because of their height and steep topography) - Can happen with or without volcanic eruptions As lahars move downslope they: 1. Increase in size/spread out 2. Slow down 3. Can grow 10x larger than their initial size 4. Come to rest like a sheet of concrete - One of the greatest volcanic hazards because they can occur during an eruption and after an eruption - Can occur without warning and can travel long distances beyond a volcano - Can lead to severe and chronic flooding in the river system Lahar Example: Nevado del Ruiz

What happened at Lake Nyos in Cameroon, and why (last lecture)?

Lake Nyos, Cameroon disaster 1986: - Crater lake (crater produced by eruption) - Magmas beneath the lake are degassing CO2 and dissolves in the water at the bottom of the lake - Overturning events cause that CO2 to quickly exsolve and release CO2 gas: - Overturning was probably triggered by a landslide along the flank of the lake and into the lake, causing the water at the bottom to be disturbed - 1,700 fatalities and a lot of livestock deaths - Scientists produced artificial geysers at the bottom to continuously release CO2 gas so it doesn't build up again

What happened when Laki erupted?

Laki Haze: - Erupted in 1783 (mainly) - 15 km3 basalt erupted from fissure - Flooded 565 km2 (like covering Chicago in 75 ft. of lava) - 200 megatons of aerosol H2SO4 emitted + other acid gasses (particularly HF) - Plume rose to Tropopause and dispersed - Eruption was particularly rich in fluorine which turned into hydrofluoric acid which is extremely poisonous - Effects in Iceland and Europe were severe - Acid flumes and rain harmed vegetation - Fluorine poisoning killed grazing animals in Iceland - Sulfur dioxide turned to sulfuric acid and produced acid rain which killed vegetation. This in turn led to famine in parts of Europe - Locally, fluorine and sulfur dioxide releases led to the deaths of 20% of Iceland's population and an additional 20,000 deaths in England - 2 degrees of cooling in the N. Hemisphere for 3 years

You should be familiar with the variety of different volcanic hazards that we discuss, know whether impacts of these hazards are primarily manifested at a local vs. a global scale, and know what kinds of eruptions (and what kinds of volcanoes) different hazards are associated with.

Lava Flows: - Melted rock with temps up to 1,300 degrees celsius (2,400 degrees fahrenheit) - Flows can move at velocities as high as 100 km/hr (60 mph) or as slow as a m/day - Lava flows can be very hot and move similarly to a fluid Pyroclastic Flow: - Mixtures of hot rock particles and gas - Denser than air - Move at velocities of 10-300m/sec (22-700 mph) Pyroclastic Surge: - low density flow of volcanic material with more gas than rock Ash Clouds: - Mainly pose a threat to air travel - Ash clouds impede air travel because they can travel quite far into our atmosphere - Ash is mostly glass fragments so the heat of jet engines can melt the ash. This coats the engine with melted material and causes them to shut down - KLM Flight 867 flew into the ash cloud produced from Mount Redoubt and all 4 engines shut off - Good news is that the engines can restart once they fly out of the ash cloud - This event prompted the USGS to put in a large monitoring network in the Aleutian Islands, Alaska Avalanches: - lots of gases are released Climate Change Fallout and Ballistics: - volcano bombs can be large Lahars and Debris Avalanches: - Volcanic gases (local to global scale effects) - Lahars are basically volcanic mudflows are quite dangerous - Local: suffocation and lung damage - Global: climate change - Volcanic gases are unhealthy for the local population to breathe in and can cause changes to the global climate if there are enough gases released

Know what Lidar is and how it is used to find landslides

Lidar: Technique for measuring distances and topography using lasers - The laser can penetrate portions of the vegetation to reach the ground surface - A large population of points can generate a point cloud that forms an image - Bare earth models remove the effects of topography and just show you the underlying surface - Lidar can also show you offsets created by active falls - Lidar shows you that the region around the oso has experienced several mass movements in the past

What is magma?

Magma is molten rock beneath the surface

What is the difference between magma and lava?

Magma: - Molten rock beneath the surface Lava: - When magma emerges on the surface

What are the major classifications of mass wasting events?

Major Classifications of Mass Wasting Events: 1. Rock Falls: - Free falling rocks 2. Rock Slides: - Rocks slide along a defined plane 3. Creeps/slumps: - Gradual mass movement, commonly related to freeze-thaw 4. Flows: - Materials behave like a fluid (earthflows, mud flows, debris flows, and avalanches) 5. Landslides: - Mass movement along defined slip planes (usually planes of weakness) - This term is used to describe any kind of mass wasting or slope failure

What is mass wasting?

Mass Wasting: Downward movement of Earth materials (rock, soil, etc) under the force of gravity - Can be slow, fast, large, small, or wet - Important component of erosion

Know what happened at Mt. Pelee and St. Pierre.

May 8, 1902 Mt. Pelee - St. Pierre: - Biggest volcanic disaster of the 20th century was due to the 1902 eruption of Mt. Pelee on the carribean island of Martinique - Something about the eruption caused a lateral blast and completely destroyed the town of St. Pierre with only 1 survivor

How do the structure of hillslopes influence mass wasting?

Nature of Hillslope materials: - Consolidated (solid rock) vs. unconsolidated (soils, gravels, sands) - Granite, basalt, and quartzite will hold their position against gravity - Unconsolidated materials such as soil, clay, sand, and gravel are more susceptible to movement Structure of Hillslopes: - Planes of weakness between soil layers - Pre-existing slip planes - Presence and type of vegetation The Role of Slope Angle: - The steeper the slope, the less stable it is - Angle of Repose: - The steepest angle that a slope can maintain without collapse/steepest angle a granular material can maintain without sliding 3 Things Angle of Repose Are Controlled by: 1. Grain size: Finer material has a lower angle of repose and slides along shallower slopes 2. Grain angularity (how round the grains are): Rounder material has a lower angle of repose and slides along shallower slopes 3. Water Content

What happened at Nevado del Ruiz in Colombia? What made this tragedy so deadly?

Nevado del Ruiz (2nd worst volcanic disaster in the 20th century): - Highest columbian volcano (5,389 m; 17,500 ft) - Summit is covered with snow and ice and main craters lie near ice pack - The town of Armero was built on lahar deposits from 1845 (Building on top of lahar deposits is a very bad idea because they're likely to flow in a similar way in the future) - Volcano is surrounded by glaciers and has a long history of producing lahars when it erupts History of generating Lahars: - 1595: 636 people dead in lahar - 1845: 1000 people dead in lahar flooding the upper of river lagunilla - November 13th, 1985 (main event we focused on): - A year of minor earthquakes - 3:06pm initial stem explosion - 7:00pm Red Cross orders evacuation - Ashfall stops, evacuation was called off - 9:08pm pyroclastic eruption (but storm obscures volcano summit) - 10:50pm Lahar reaches the town of Armero killing more than 23,000 people What went wrong in this event? - Officials didn't act in the best interest of the people and there was a general lack of information and monitoring equipment What does this demonstrate? - This demonstrates the urgent need for monitoring equipment for volcanoes near population centers

Know what normal forces and shear forces are, and how they are related to mass wasting events.

Normal force: - Force acting perpendicular to a surface - holds the material in place on a slope Shear force: - Force acting parallel to a surface; induces sliding - Moves material down the slope - To slide the shear force must overcome the normal force AND friction

How does pahoehoe lava differ from a'a lava? Why do the two types of lava differ (what properties change)?

Pahoehoe: - is fluid lava, less viscous, and forms smooth ropy surfaces A'a: - More viscous, jagged blocks Property changes: - Basalt flow can transform from Pahoehoe to a'a with loss of gas and temperature, which increases viscosity - As pahoehoe continues to erupt and flow, it decreases in temperature and gas content. This decreases the viscosity and the pahoehoe can transform in a'a

Under what conditions do pillow lavas form?

Pillow Lavas: - When lava flows underwater, they form pillow lavas - Outer skin cools rapidly to form glass - The outer edge of the pillow lavas cools very rapidly when it interacts with the cold water and forms a glassy outer skin

Know the characteristics of pyroclastic fall and flow deposits

Pyroclastic fall deposits: - Extensive sheet-like deposits of ash and pumice lapilli - Materials falls out of eruption column - "Umbrella region" - "Sorted" (sorted means that it becomes gradually smaller or gradually bigger) - Grain size and deposit thickness varies with eruption - intensity and decreases away from vent size - Primary hazard is burial and building collapse Pyroclastic flow deposits: - "unsorted" - Large chunks of material surrounded by finer material

How does a pyroclastic flow differ from a pyroclastic surge, in terms of behavior? How do they rank in terms of destructive capacity?

Pyroclastic flows and surges: - Mixtures of hot rock and gas - They can move up to 330m/sec and as slow as 10m/sec - The deadliest of all volcanic phenomena - A fluidized mixture means that they can travel down valleys and follow the local topography - A fluidized mixture of solid to semi-solid fragments and hot, expanding gases that flow down the flank of a volcanic edifice 2 end-members (and deposit types): 1. Flows: - have less gas and more rock particles ---> denser than air - reach immense volumes in ultrapilian eruptions 2. Surges: - Surges have higher gas concentration ---> less dense - In general, travel faster than flows

Know the details about Tambora's big eruption-how did this impact climate globally? What were the effects on people living both nearby and far away? How does the scale of this eruption compare to what might happen if Yellowstone erupted?

Tambora, Indonesia global impacts: - 1816: Famine in New England remembered as "the-year-without-summer" or "eighteen-hundred-and-froze-to-death" - Called the year without summer because of global cooling after the eruption - 1817: Famine in Germany: "The year of the beggar"; Ireland 100,000 people dead (mass exodus) - Typhus, bubonic plague, and cholera epidemics in SE Europe, E mediterranean, and India left 100,000 people dead - Gloom and cold led to Mary Shelley's novel, Frankenstein - Several famines worldwide also led to the spread of disease Increased Albedo: - Injection of ash and volcanic gases, particularly sulfur dioxide, into the upper atmosphere led to an increase in albedo (reflection of solar radiation) which in turn led to cooling - This also happened in the 1991 Pinatubo eruption Scale comparison: - If this were to happen at Yellowstone in the US a relatively small eruption could have ash fall in Iowa - 2-8 cm ash deposition in Des Moines depending on the season

What is tephra? What is a tuff?

Tephra: - Tephra is the unconsolidated material - A general term for all types of pyroclastic material produced by a volcano Tuff: - Tuff is the rock formed by the consolidation of that material - Consolidated tephra - A rock formed by consolidation of Ash and other fragmental volcanic material

How do most hurricanes start (what generates the initial disturbances that build into thesestorms)? Where do they start? We discussed several mechanisms in class.

They start by being tropical storms in warm moist waters. Hurricane energy is derived from heat stored in ocean water. Most hurricanes that hit the United States begin either in the Caribbean or the Atlantic. Many of the worst start as seedlings coming off the coast of Africa.

What are the other hazards associated withthese storms?

Tropical Cyclone Hazards: - Intense rainfall - Storm surge - Possibly tornadoes

How high can winds be in a tropical cyclone?

Tropical Cyclone Winds: - Can have sustained winds as high as 215 mph

What is a tropical cyclone?

Tropical Cyclone: "Greatest storms on Earth" - "A warm-core, non-frontal cyclone, originating over tropical or subtropical waters, with organized deep convection and a closed surface wind circulation about a well-defined center" - In tropical cyclones, winds are circulated about a well-defined center - Sustained winds as high as 215 mph - Symmetrical - A tropical cyclone is fueled by the extraction of heat energy from the ocean - Cyclonic storms CAN occur anywhere, BUT tropical cyclones are fueled by tropical or subtropical waters - Intense areas of rainfall and storm surge, possibly tornadoes - Variety of names depending on: Location, Strength, and Wind Speed Names: 1. Tropical Depression: 20-34 knots or 23-39 mph 2. Tropical Storm: 35-63 knots or 40-73 mph 3. Hurricane: 64+ knots or 74+ mph -"Hurricane" = (North Atlantic, East Pacific) - "Typhoon" = (West Pacific) - "Cyclone" = (Indian ocean, South Pacific)

What happened in the Vaiont Dam disaster?

Vaiont Dam disaster: In October 1963, A massive landslide fell into the reservoir behind a hydroelectric dam generating a tsunami - This landslide displaced a lot of water and caused a tsunami that overtopped the dam and flooded the villages below killing a total of 3,000 people - This area had experienced slides before and was prone to them - There were fissures forming at what would become the head scarp later on

What is viscosity a measure of, and what three factors interact to determine the viscosity of magmas/lavas?

Viscosity: The ability of a substance to resist flow. Controlled by 3 things: 1. Temperature 2. Composition 3. Gas content - Higher temperature = more fluid Honey Example: - When honey is cool and at room temperature its very sticky and goopy (higher viscosity), the marble sank very slow - When honey is hot, it flows much easier (lower viscosity). The marble sank more rapidly

What is the VEI, and how does the volume of material and style of eruption erupted relate to VEI scores?

Volcanic Explosivity Index (VEI): The measure of intensity of a volcanic eruption with a value of 0 representing the quietest and 8 being the most explosive - Values range from 0-8, with the vast majority of event receiving values of 1 or 2 - Based on how much magma is erupted in an explosive eruption - Each step up in the VEI is an order of magnitude higher volume of erupted material - Large eruptions are far less frequent than smaller eruptions

You should know the types of gases that are released during volcanic eruptions, and their impacts.

Volcanic gases: - H20, CO2, SO2, HS, HF, HCI are all released during eruption Global Impact: - Climate change Local Impact: - Suffocation and lung damage - CO2 is especially dangerous because it is denser than air so it can accumulate in valleys and displace breathable air

What does volcanism tell us about the Earth's interior?

Volcanoes are important because they are a major hazard, they produce new crust (continental and oceanic), and geologists can learn about the interior of the Earth from the rocks they erupt, and they are major tourist attractions

What kinds of weather and topographic patterns and conditions make an area likely to have a severe wildfire? This explanation should include general trends between having a wet vs. dry climate as well as topography and winds.

Weather Formula for Wildfire: Warm temperatures + low humidity + stronger winds = Increased potential for wildfire - Wet topography is less likely to burn than dry topography - Most north-facing slopes are wet because they don't receive as much sun as south-facing slopes. This allows them to remain moist and vegetated. - When the fire is on a slope, the material uphill of the adjacent fire is preheated uphill - This is why fires tend to spread uphill - Wind pushes the fire and changes the direction of heat flow - If there are strong winds then the fire can expand to greater distances - More wind means more oxygen to fuel the fire

Know the different regional names for cyclonic storms. You should also know theclassifications (i.e., what is bigger, a tropical depression or a tropical storm? How arethese categories defined?).

What Do Cyclonic Storm Names Depend On? 1. Location 2. Strength 3. Wind Speed Cyclonic Storm Names/Categories: (smallest to biggest) 1. Tropical Depression: 20-34 knots/23-39 mph 2. Tropical Storm: 35-63 knots/40-73 mph 3. Hurricane: 64+ knots/74+ mph - "Hurricane" = (North Atlantic, East Pacific) - "Typhoon" = (West Pacific) - "Cyclone" = (Indian ocean, South Pacific) How are Cyclonic Storm Categories Defined? Through the Use of the Saffir-Simpson Scale: - Ranks (1-5) damage potential of land-falling hurricanes according to sustained wind speeds - Scale is NOT defined by pressure, BUT generally the lower the atmospheric pressure is, the more intense a tropical cyclone is - Considered "major" when it reaches Category 3: (sustained winds of 111+ mph) Lowest Recorded Pressure: - 1979 Typhoon Tip - Pressure was 870 mb (25.69 in Hg) Highest Recorded Wind Speed: - 2015 Hurricane Patricia - 215 mph or 345 km/hr - 872 mb (25.75 in Hg)

Why do we need warm ocean surface water for hurricanes to form, and how deep does this water need to be?

Why Do We Need Warm Water for Hurricanes? - We need warm water (27 degrees celsius/80 degrees fahrenheit) to act as the "fuel" in the hurricane - Warm water evaporates from the ocean and reduces the pressure at the surface - Reduced pressure at the surface creates more rapid air flow How deep does this water need to be? - 50 meters deep or 160 feet deep

What has the United States done, in terms of how we have treated wildfires over the years? How has this impacted fuel availability, as well as the likelihood of fires becoming crown fires?

Wildfire Mitigation: On the ground treatments of forested areas to reduce the threat of wildfires, typically by removing fuels Prescribed Burns: - Planned, controlled fires designed to reduce fuels and improve forest health - Homes built with tin roofs remove the fuel provided by traditional fires Create Firebreaks: - Fuel-free barriers created to contain a wildfire - Includes burnouts Backburn: - A prescribed burn that extends from a firebreak toward the wildfire Cold Trailing: - Following a wildfire to extinguish smoldering materials Aerial Dousing: - Dousing wildfires with water and fire retardants

What general trends are we seeing with wildfires in the United States and globally in terms of both frequency and size? Where are wildfires a hazard in the U.S.?

Wildfire Trends in the US: - Concentrated in the west and southeast - In general, the number of wildfires in the US per year is slightly decreasing through time. HOWEVER, the number of acres burned per fire is exponentially increasing - Climate change and fire management control these trends