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geg133 Flashcards

1
Q

what’s the definition of natural hazards

A

“any natural process or phenomenon that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption or environmental damage”
United Nations International Strategy for Disaster Reduction (2009)

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2
Q

percentage Number of deaths from each disaster types 1998-2017

A

56% earthquake
17% storm
13% extreme temperature
11% flood
2% drought
1% landslides
0.2% wildfire, volcanic activity, mass movement (dry)

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3
Q

percent Number of people affected per disaster type 1998-2017

A

45% flooding
33% drought
16% storm
3% earthquake
2% extreme temperature
0.1% wildfire etc,
0.1% landslides

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4
Q

what is the equation for risk

A

Risk = hazard * exposure * vulnerability

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5
Q

what is risk

A

Risk is the likelihood or probability of loss of life or destruction and damage over a given period of time

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6
Q

what is vulnerability

A

Vulnerability = Ability to cope (with risk)
* Depends on:
* exposure to risk
* economics – poverty
* society – change
* politics & governance
* experience
* preparation
* Resilience = ability to recover

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7
Q

what does the hazard come from

A

Hazard, comes from the Persian word for dice (“zar”)
Dicing with Death (Taming Chance)

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8
Q

before the modern age what were the explanations for natural disasters

A
  • Before the modern age, floods, earthquakes, landslides, volcanic eruptions, etc. were the gods speaking through the fabric of the Earth: But what was He saying? And to whom
    • Major disasters expressed Divine Wrath, and this notion still echoes down the ages
    • Humanity was not ‘exposed’ to accidents or risks. It was subject to fate / destiny, knowledge of which was reserved for the gods.
    • Risk – “to defy, challenge, dare, face off” the gods; to “run into danger” – a choice not fate.
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9
Q

what was the car caused disasters from the 18th and 19th century’s

A

Car trouble: key symbol of individual ‘liberty’ & ‘freedom’ – a licence to kill?
Despite attempts to ‘mitigate’ this century-long disaster, we knowingly tolerate:
- ~3,500 people killed each day in car crashes (mostly poor pedestrians in cities)
- ~1.5 million killed each year in car crashes (and many times more seriously injured)
- Worldwide ratio of car deaths to war deaths & murder is currently ~3:1

In US alone:
- Since 1899, 3x more Americans have been killed by cars than by war!
- e.g. During Vietnam War: 10x more Americans killed by cars than in combat
- Each month, about the same number are killed on roads as were killed in 9/11
- Annual cost of car crashes ~$95 billion: loss of life, loss of work, medical costs
- Only in 3 of last 50 years did ‘Natural Disaster’ deaths exceed road deaths!

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10
Q

what is the joy of risk

A

Humanity has always been ‘exposed’ to threats (e.g. ‘natural’ disasters & socio-technical ‘accidents’). But modern society increasingly subjects itself to a new type of threat that comes from modernization itself: modern risks are produced by human activity.
- From car crashes to nuclear or climate Armageddon

A Risk Society is especially concerned with these socially ‘manufactured risks.’
- corporations, governments & experts are entrusted with their management, so that disasters don’t occur.
- mistrust underpins the ‘precautionary principle.

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11
Q

Why do we need to communicate hazards?

A
  • Save lives and avoid injuries
    • Increase resilience (being ready)
    • Minimise vulnerability
    • Educate and improve understanding
    • To improve trust and relationships between “expert” and the wider population
    • To collect data and improve hazard modelling and prediction
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12
Q

Who are we communicating?

A
  • Local residents
    • Tourists (timings, information)
    • Officials
    • Policy makers (difficult to convivence without evidence)
    • Scientists
    • Indigenous people
    • Media
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13
Q

What do we need to consider while communicating about hazards?

A
  • Age (vulnerability and transport)
    • Ethnicity (possible poor relationship with government, neglected)
    • Gender and sexuality
    • Economic status (will they be able to afford the evacuation)
    • Education
    • Understanding
    • Culture and religion
    • Agenda
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14
Q

When should we be communicating?

A

Before
- Education
- Community Programmes
- Historical and Cultural Understanding
During
- What’s happening?
- Where is it happening?
- Is there a need to evacuate?
- Where should you go?
- What should you take?
After
- What happened?
- Is it safe to return?
- What help is available?

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15
Q

What do we need to communicate?

A
  • Danger!
    • What are the Hazards?
    • What are their impacts?
    • Where are the no-go areas?
    • What are the evacuation procedures?
    • Has this happened before?
    • Science
    • Technology (radio and TV announcements, text alerts, breaking news items, Live web cams)
    • Social media
    • Signs, sirens and Languages - Accessible communication
    • Art installations
    • Tourist destinations and museums
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16
Q

what are the earthquake origins

A
  • Human activity, e.g. fracking, reservoir building, mining
    • Volcanogenic earthquakes, movement of magma causes surrounding rocks to crack
    • Meteorite impact
      Fault movement
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17
Q

Where do the earthquakes common occur?

A

along the faults in the earths crust

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18
Q

what are the types of convergent plate margins

A
  • Collision of two plates
  • Destructive margins, subduction zones
  • Can generate earthquakes and volcanic activity
  • Range of earthquake depths
  • Also continental – continental collision
  • Can generate earthquakes and mountain building
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19
Q

what are divergent plate margins

A
  • Two plates being pulled apart by mantle convection
  • As they pull apart they crack and fault
  • Earthquakes generated at these faults
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20
Q

what are conservative plate margins

A
  • Lateral movement
  • Shallow earthquakes
  • e.g. San Andreas fault, North Anatolian fault
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21
Q

what are intraplate earthquakes

A
  • Slow strain accumulation
  • Long recurrence intervals
    Example
    • New Madrid seismic zone
    • Dec 16 1811: M7.7
    • Jan 23 1812: M7.5
    • Feb 7 1812: M7.7
  • several aftershocks >M6
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22
Q

what do “focus” and “epicentre” mean in seismology

A

Focus = point of origin
Epicentre = on surface directly above focus

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23
Q

what are P waves and S waves

A

p waves result from compression and stretching in the direction of travel
* compressional (push-pull)
* fast (5 km/s through crust)
* travel through solid and liquid

s waves vibrate up and down or side to side perpendicular to the direction of travel
* shear (perpendicular to travel direction)
* slower (3 km/s through crust)
* travel through solids Surface waves

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24
Q

what is the largest earthquake since 1900

A

mag. 9.5, Chile 1960

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25
Q

what are the scales used to measure earthquake damage

A

● Modified Mercalli scale(I-XII)
● European Macroseismic Scale (1-12)

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26
Q

what are the primary hazard of the earthquakes

A
  • Ground shaking by seismic waves
  • Therefore causing the collapse of buildings
    • Surface rupture
    • Offset on the ground surface
    • Vertical or horizontal

Uplift/subsidence

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27
Q

what are secondary hazards of earthquakes

A

Liquefaction = Disturbance of loosely packed (unconsolidated) sediment due to shock, Temporary fluid behaviour
- Landslides
- Caused by seismic shaking (usually from earthquakes rated 5 or more)
- Sometimes occur due to liquefaction
- Sometimes rock falls or rock avalanches
- Can be more damaging than the earthquake
- Number of landslides induced by EQs decreases with increasing distance from the epicentre
Number of landslide increases with larger magnitude EQs

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28
Q

explain facts around Mt. huascaran, Peru (1970)

A
  • ancash EQ (M7.9) led to N. side of mountain collapsing
  • 80 mil. m^3 avalanche of rock, mud and ice
  • advanced 18km (11 miles) at ~200mph
  • > 20,000 deaths from landslide, >66,000 from EQ
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29
Q

what is palaeoseismicity

A
  • Dating movements on faults
  • Dated landslides, tsunamis
  • Evidence for liquefaction
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30
Q

what type of volcanoes/volcanic eruptions are there

A
  • Stratovolcanoes
    Volcanoes can range from small monogenetic landforms (e.g., lava domes, cinder cones) to large stratovolcanoes, even bigger shield volcanoes and calderas
    • Calderas, Shield volcanoes
      Volcanoes can range from small monogenetic landforms (e.g., lava domes, cinder cones) to large stratovolcanoes, even bigger shield volcanoes and calderas
    • Monogenetic landforms, lava domes and scoria/cinder cones
      Volcanoes can range from small monogenetic landforms (e.g., lava domes, cinder cones) to large stratovolcanoes, even bigger shield volcanoes and calderas
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31
Q

Types of explosive eruptions - Magmatic (increasing explosivity)

A
  • Hawaiian
    • Strombolian
    • Vulcanian
      (sub)Plinian
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32
Q

Types of explosive eruptions - phreatomagmatic (water and magma mix) (increasing expolosivity)

A

By adding water explosions become more violent
- Strombolian
- Surtseyan
- Plinian
Phreatoplinian

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33
Q

which country has prime examples of Divergent (or constructive) Plate Margins

A

Iceland
ex. Holuhraun 2014-15

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34
Q

what is Volcanic Hazards: Tephra fall (ash fall)

A

When the volcanic blows, all the rock and magma that gets push out by the gas and causes fragmentation of the magma called tephra / pyro clasts
Ash (< 2mm); Lapilli (2-64 mm); Blocks/Bombs (> 64 mm)
This can cause blockades, damage to buildings and people, as well as cause aspiratory issues, and blocking flights

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35
Q

what is Pyroclastic density current (PDC)

A

Liquidizes mix of liquid and solids
Pyroclastic density current : fluidized mixture of solid to semi-solid fragments and hot, expanding gases.
Flows down the flank of a volcanic edifice, often at over 100 km/hour.
- Dense basal flow made up of large blocks and ash –valley confined
- Upper, turbulent dilute flow fed by mixing at head of flow; can separate from basal part; then called pyroclastic surge. Can travel uphill!

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36
Q

what are some of the gases released from volcanic gases

A

CO2, SO2, H2S, H2SO4, HCl, HF
Examples,
- Trees killed by high carbon dioxide conc. At Mammoth Mtn., CA
- Livestock killed by catastrophic release of carbon dioxide gas from Cameroon’s Lake Nyos

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37
Q

what are Lahars

A

Lahar (Indonesian) = Volcanic Mudflow

Case study: Nevado del Ruiz (1985)
* Eruption melted ice cap
* Engulfed Armero >50 km downstream
* Killed 23,000
* Previous lahars 1595, 1845
* Hazard identified by Colombian and Italian volcanologists

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38
Q

list the volcanic hazards

A
  • Tephra falls (ash falls)
  • Pyroclastic density currents (pyroclastic flows & surges)
  • Lava flows
  • Volcanic gases
  • Volcanic mudflows (lahars)
  • Volcanic landslides
  • Volcanic tsunamis
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39
Q

what is the global volcanism program called

A

Smithsonian Institution

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40
Q

when do most deaths occur after a volcanic eruption

A

between 1 month - 6 months

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41
Q

what are the first five countries where 90% OF volcanic risk is.

A

Indonesia
Philippines
Japan
Mexico
Ethiopia

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42
Q

reasons why people return early to eruption zones

A

A lot of people go back to early, in order to try and protect their assets and homes.
Other factors are caused through the mass evacuation, such as disease from crowding, mental health issues and boredom from being force away from their homes, conflict with centres and general lack of food and water.

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43
Q

what are the types of volcanic forecasting

A

Long-term Eruption Forecast
* Relates to the coming years, decades or longer
* For most long-range forecasts, the volcano in question is dormant and any seismic, ground deformation or fumarolic activity is at background levels

Volcanic Hazard Maps – Identification of Hazard Areas
Hazard maps are often the end product of risk identification and analysis
Used for planning evacuation and other preparation

Short-range Eruption Forecast (Prediction)
* Relates to the coming hours, days and weeks
* Short-range or ‘immediate’ forecasts or warnings are issued when unrest (or an eruption) is escalating sharply or a hazardous eruption has just begun

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44
Q

types of volcanic ground monitoring

A

Seismic Monitoring
Moving Magma and Volcanic Fluids Trigger Earthquakes

Ground Deformation
Caused by magma moving under the ground, causing deformation and shape changes on the sides of the volcano
Types of monitoring
electronic distance measurements
global positioning system (GPS)
Tilt Measurements
Satellite Radar Interferometry

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45
Q

types of volcanic gas monitoring

A

ground based remote sensing

direct gas sampling and analysis

continuous on-site gas monitoring

soil co2 flux/conc. measurements

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46
Q

types of satellite remote sensing

A

tracking eruption clouds

detecting so2 in eruption clouds: TOMS

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47
Q

types of volcanic hydrological monitoring

A

detecting lahars in real time

surveying river channels

measuring sediment on the move

sampling/analysis of water sample

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48
Q

example of community-based monitoring

A

For example the Vigias of Tungurahua (Ecuador)

scientists required native people who live on the volcano to monitor it

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49
Q

what are killer lakes??

A

Killer-Lakes”: Draining the Kelut Crater Lake, Indonesia
* 5,000 people were killed during 1919 eruption → an engineering project tried to drain Kelut’s crater lake
* Initial work lowered the lake > 50 m, but the 1951 eruption deepened the crater by 70 m
* After more than 200 people were killed in the 1966 eruption, a new deeper tunnel was constructed, lowering the lake’s volume to only about 1 million m3 prior to the 1990 eruption

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50
Q

how many slope failure risk areas do we have in the UK

A

Uk:
- >18,000 features Known (BGS)
- Many dormant (happened in the past unlikely to happen in the future) or fossil

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51
Q

what are the main components of a landslide

A

source/crown
head
scrap
body/chute
toe/fan

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52
Q

what are the factors to slope stability

A

Stability is balance of:
- Driving force (shear stress, gravity)

- Function of
Weight (mass)
Slope angle

- Resistance of slope materials (shear strength)

- Function of
Cohesion Friction
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53
Q

what is the name and equation for slope failure

A

The Mohr–Coulomb failure criterion

τf = c + σtanφ
Where τf is the shear strength, σ is the effective normal stress on the failure plane, and c and φ are cohesion and friction angle, respectively.

54
Q

what are some of the landslide triggers

A

Landslide Triggers
Water – rainfall, snowmelt, frost thaw
Seismic activity
Human activity

55
Q

example of an earthquake triggering a lot of landslides

A
  • 2008 Wenchuan (Sichuan) earthquake
    • M 7.9
      Triggered >56,000 landslides
56
Q

what are the types of slope failure

A

rotational landslide
translational landslide
block slide
rockfall
topple
debris flow
debris avalanche
earthflow
creep
lateral spread

57
Q

landslide characteristics

A

Landslide characteristics
Volume: single boulder -> km^3
Velocity cm/y -> 100s m/s

Horizontal travel distance
Small: 2x fall
Large 10x fall (long-runout)

58
Q

what are snow avalanches

A
  • Masses of snow that descends steep slopes, they can contain rocks, soil, vegetation or ice
    • Two type of release,
      Loose snow avalanches
      Slab avalanches
59
Q

explain what a loose snow avalanche isss

A

Released from a point in a relatively cohesionless surface layer of either dry or wet snow. Initial failure is analogous to the rotational landslide but occurs within a small volume (c. 1 m3)
- ‘saltation’, entrainment of air and snow, flow, turbulence,
- gaining velocity, ‘powder’, mixing with air – buoyant clouds
- fanning out from point release
- Speeds up to 300 km/h

60
Q

explain what a snow slab avalanche iss

A

Release of a cohesive slab (usually in the order of 1 m thick) over an extended plane of weakness. Analogous to planar failure of rock slopes.

- Observed ratio of width/thickness varies between 10-1000. Slabs develop through crown fracture propagation.
- A large slab avalanche may be in the order of 250 000 m3
- High density: dry or wet, mostly fresh ‘damp snow’ sliding over old, denser snow.
- Speeds up to 150 km/h
61
Q

what increases the likelihood of an avalanche occurring

A

Slope gradient - depending on the angle the more frequent there is an avalanche and the more devastating, 45 - 34 degrees with 39 being the most frequent
Aspect (slope direction) - whether its in the same direction as the sun
Wind direction
Terrain
Vegetation
Snowpack conditions

62
Q

what is the snow slope stability equation

A

Snow slope failure has been studied with a strength-of-material approach.
Snow stability S is calculated for a given time t, depth within the snowpack, and location on the slope x. Hence the avalanche problem is reduced to the question of balance between snow strength τf and stress (normal stress σ and shear stress τ) at time t and location x:

63
Q

list landslide hazards

A
  • Impact
    • Burial
    • Structural failure
    • Secondary/multiple hazards:
      Transformations
      Displacement of water - tsunamis: ‘landslide splash waves’
      Failure of landslide dams
64
Q

example of high frequency area of snow avalanche,

A

LODALEN, NORWAY
RAMNEFJELL

January 1905
rockfall of 50,000 m3 from 500m  wave 40 m above lake
61 dead

Rebuilding

September 1936
rockfall 1 M m3 from 800m  wave 74 m high
74 dead

This case highlights that rebuilding may not be the wise case in areas of high frequency

65
Q

what are the types of avalanche hazard mitigation

A
  • Forecasting (awareness)
    • Non-structural methods include avoidance (land use restrictions or temporary evacuation) and artificial triggering.
    • Structural measures include structures to divert and retard and starting zone structures design to prevent avalanche initiation, or forest management.
66
Q

types of wild fires

A
  • Wild fire (uncontrolled vegetation fire)
    • Wildland fire (controlled or uncontrolled vegetation fire)
    • Prescribed/management fire (controlled vegetation fire)
      Australia “bushfire”
67
Q

what are the occurrence of wild fires world wide

A
  • natural part of Earth’s environment
    • Common in all climates with dry periods
    • ignited by
      lightning (100,000 strikes per day)
      rockfall sparks
      volcanic eruptions
      human activity (primary cause in many regions)
    • 3-4 million km2 burn annually worldwide
    • 3 % of global vegetated land surface
    • ~20 x size of UK
      humans burn > 1 million square km2 of forest and grassland around the world per year
68
Q

TRUE OR FALSE, wildfires are the more costly per person affected than earthquakes or floods usually are?

A

TRUE

69
Q

Occurrence of wildfires in the UK

A

Example UK:
* Many 1,000s vegetation fires every year
* almost all fires by arson
* South Wales: greatest frequency of arson and fire in UK
* 8 x the UK average

70
Q

what are the impacts during a wildfire

A
  • Direct fatalities during fire
    • Damage - disruption through gases - smoke
      Suffocation; CO2 poisoning; lung tissue damage
      Longer term smoke exposure: >300,000 premature deaths per year
      Traffic hazard
71
Q

what are the post fire impacts of wildfires

A

Post-fire impacts:
* Flooding and erosion
Soil water repellency

72
Q

what are the broader ecological impacts of wildfires

A
  • Negative
    Emission of toxins and greenhouse gases
    Fires emit equivalent one quarter of global C emissions from fossil fuel (but most is sequestered again by regrowing vegetation)
    • Positive
      Removal of “old” vegetation
      Trigger for seeding or seed germination
      Increases in species diversity
73
Q

what are some of the infamous example of wildfires globally

A

2016, Fort McMurray, Canada, 60,000 evacuated, $9 billion

2017, Portugal, 2 major fires, 104 deaths

2018, Mati Greece, 102 deaths

2018, Paradise California, 85 deaths, $16.5 billion loses

2019/2020, black summer bushfires, SE Australia, 34 direct deaths, 445 indirect deaths (smoke inhalation), >9000 buildings destroyed, $AU 103 billion losses, 10 x the forest area typically burned in large Australian fire season

74
Q

what are the risks and trends globally with wild fires

A

Risk and trends:
* Globally average area burned declined ~20% in last two decades
* BUT increases in fire in most of world’s forest areas
* Effects of past management practices and changing climate amlter fire regimes

75
Q

what are some of the mitigation methods for wildfires

A
  • Prevention
    Fuel reduction burning
  • Vulnerabitlity reduction
    Building guidelines
  • Observation and risk reduction
    Fire towers
    Aerial patrols
    Closure of high risk areas
  • Event modification
    Hosing
    Water-bombing
    Back burning
    Fire breaks
  • Evacuation
    Environmental impacts: e.g. water quality
76
Q

what are the el nino and el nina climate patterns

A

caused by trade winds,

el nino the weakening of trade winds in Asia causing the warm water to flow towards South America, reducing the amount of cold water well in North America, most prevalent in December, bringing floods in the south USA, and dryer conditions in the upper sectors

el nina is when the trade winds push the warm water back causing the effects to reverse

77
Q

how often do EL NINO patterns return?

A

2 to 7 years

78
Q

impacts of el nino patterens (ESNO)

A

Western pacific
- Droughts

Eastern pacific
- Crashes fishing economy

ENSO linked to droughts, floods, landslides, storms, wildfire
El Nino tend to be the hottest years

79
Q

how do we prepare for ESNO

A

Predictions, warning, preparations and planning to reduce the risk
- Predictions improved considerably - several months in advance
Read Guimaraes Nobres et la. 2019

80
Q

what is the Atlantic Meridional Overturning Circulation

A

The Atlantic meridional overturning circulation (AMOC) is the “main current system in the South and North Atlantic Oceans”. It is a component of Earth’s oceanic circulation system and plays an important role in the climate system.

This process, along with winds, drives the Atlantic Meridional Overturning Circulation part of the global thermohaline circulation

There is evidence suggesting this is weaking from climate change

Linked to changes with the cryosphere

Increases in Antarctic and loss in Greenland means there is a exponential increase in freshwater input to ocean surfaces

Ocean becomes more stratified

Positive feedback - Antarctic ice shelves are in contact with deep…..
Stronger gradients of temperature = stronger storms

81
Q

what are storm events

A

WHO:
“From 1998-2017, storms, including tropical cyclones and hurricanes, were second only to earthquakes in terms of fatalities, killing 233 000 people.

During this time, storms also affected an estimated 726 million people worldwide, meaning they were injured, made homeless, displaced or evacuated during the emergency phase of the disaster.”

82
Q

what is hurricane

A
  • A tropical cyclone (also called typhoon)
  • A rapidly rotating storm system
  • Thick clouds spiral around the clear eye
  • Low pressure centre (~ 950 mb)
  • Strong winds (> 32 m/s)
  • ~500 km diameter
83
Q

what is the hurricane scaling called

A

Saffir-Simpson Hurricane Intensity Scale

84
Q

Hurricane dissipation factors

A
  • Tropical cyclones can last 7-20 days
    • Storm hits land or reaches cold waters
      Supply of latent heat is cut off
      Weakens and dissipates over few days
85
Q

what are the hurricane hazards

A
  • Strong winds
    Typically 120-250 km/h
    • Heavy rain
      Up to 250 mm/day
    • Storm surges
      Rising sea levels and strong waves

Greatest damage from secondary events:
Floods
Landslides
Tornadoes

86
Q

what are the mitigation strategies for hurricanes

A

Mitigation: Forecasting
Satellite data and models were available for forecasters
Warning was issued several days in advance of landfall

Satellites are primary use to survey these storms, however they are often couple with sea boys and recently drones in order to give strong predictions.

There are fixed routes, however due to the nature of hurricanes the use of planes are dire in order for the mobility to track this hurricanes

Mitigation: Evacuation
Mandatory evacuation was issued for the city of New Orleans

Tens of thousands fled
Many stayed: poorest, elderly and people with limited access to transportation

87
Q

what are the statistics about hurricane katrina 2005

A
  • Hit Louisiana 29th August 2005
    • Category 3, 193 km/h
    • Most expensive hurricane ($108 billion)
    • 1,800 fatalities
    • 7.5 m storm surge
      Weakened to a tropical storm the following day

10-30,000 sheltered in the New Orleans Superdome, which sustained damage

Levees (flood walls) were poorly constructed and dated

Over 50 levees failed, causing widespread flooding in New Orleans
Over 80% of the city flooded, up to 2 m in some areas

Failure of levees caused the most impacts and deaths
Drowning caused a third of all deaths

Aftermath
* 1,800 deaths
* Drinking water contaminated for 5 months, health hazard
* 1 million houses damaged, 300,000 destroyed by flood
* 500,000 people homeless
* 230,000 jobs lost

88
Q

what are some of the after affects of hurricanes

A
  • Demographic shifts
    400,000 people permanently displaced
    Population of New Orleans decreased by 29% between 2005 and 2011
    • Employment
      230,000 jobs lost after Katrina
    Employment recovery:
    Better for higher income groups
    Other groups disadvantaged (women, black communities and those who moved)
    • Long-term mental health problems
      Recorded 5 years after Katrina
    PTSS - post-traumatic stress symptoms
    PD - phychological distress
    Secondary trauma: loss of home and/or communityHigh earning individuals had less of a risk of developing PTSS or PD
89
Q

what are tornadoes

A

A violently rotating column of air in contact with the ground and a cumulonimbus cloud.
* Form in moist air ahead of a strong cold front
* Duration: minutes to hours
* Size: <1 km across
* Travel a few km
* wind speeds 105–450 km/h

90
Q

what is the tornado classification

A

Tornadoes are classified according to the Enhanced Fujita Intensity Scale
USA tornadoes: 69% weak, 29% strong, 2% violent

91
Q

what is the tornado global occurrences

A
  • USA : 900 per year
    • UK : 34 per year
    • Bangladesh : 250 reported 1865-2014
      USA is a hotspot when it comes to tornadoes occurrences
92
Q

list the ways we forecast and mitigate tornados

A

Forecasting tornadoes is complicated

In U.S., forecasts by National Weather Service:
”When predicting tornadoes a day or two in advance, we look for the development of temperature and wind flow patterns in the atmosphere which can cause enough moisture, instability, lift, and wind shear for tornadic thunderstorms“.

93
Q

what is a heatwave

A
  • A period of high temperatures relative to typical seasonal conditions for a location.
    • “A UK heatwave threshold is met when a location records a period of at least three consecutive days with daily maximum temperatures meeting or exceeding the heatwave temperature threshold.”
    • Differenb t threshold temperatures for regions within the UK.
    • Before 2022 thresholds were based on the average of 1981-2010 temperatures, now based on 1991-2020
94
Q

what are Anticyclones

A

a weather system with high barometric pressure at its centre, around which air slowly circulates in a clockwise (northern hemisphere) or anticlockwise (southern hemisphere) direction. Anticyclones are associated with calm, fine weather.

* Large-scale high-pressure systems
* Light winds Descending air inhibits cloud formation
95
Q

how do heatwaves affect pollutions

A
  • Temperature inversions inhibit convective mixing and trap emissions
    Clear skies and hence strong radiation enhance ozone production
    England and Wales, 2003:
    21–38% of the total excess deaths due to “elevated ambient ozone and PM10 concentrations.”
96
Q

how do heatwaves affect soil moisture

A
  • Soil moisture deficits can increase the frequency, duration and severity of hot spells in moisture-limited areas (e.g. Southern Europe).
    • In wetter climates, this relationship is weaker. (Alexander, 2011; Hirschi et al. 2010)
      But: lower air humidity = reduced heat stress = mild reduction in heatwave mortality (Wouters H et al. 2022)
97
Q

who were the most vulnerable people in 2023 uk heatwave

A

65+ :share up 9.5%
85+ :share up 27%
of fatalities

98
Q

example of Long-term mitigation: urban planning

A

planting more trees in urban areas

building cool infrastructure

99
Q

what are droughts

A
  • IPCC: “A moisture deficit relative to the average water availability at a given location and season”
    • Meteorological drought: period of lower rainfall
    • Can last from days to years
100
Q

where do droughts normally occur

A
  • Occurs globally
  • More common in areas with low rainfall levels

Areas of tropics and subtropics experience distinct dry and wet seasons

101
Q

list the environmental factors of droughts

A
  • Loss of wetlands
    • Drying of seasonal water bodies
    • Reduced vegetation cover
    • Loss of wildlife habitat
    • Soil erosion
    • Wildfires
    • Wildlife migration
    • Disease
102
Q

list what are the socio-economic factors of drought

A
  • (Cash) crop failure
    • Loss of livestock
    • Irrigation costs
    • Reduced water quality
    • (Clean) water scarcity and supply disruptions
    • Decreased water supply for energy sector
    • Decreased soil fertility
    • Unemployment
    • Increased food (production) prices
    • Risk of disease
    • Mass migrations
    • Hunger and famine
103
Q

what are the facts about the drought in the sahel

A

semi-arid 100-800 mm/yr
dry and wet seasons
rainfall driven by tropical convection
West African Monsoon El Nino

causes Anthropogenic:
overgrazing, deforestation for agriculture
increased surface albedo, less solar energy absorbed
reduced moisture supply to the atmosphere, less rainfall
unfavourable conditions for vegetation growth

104
Q

how many people needed support during the Ethiopia drought 1999-2000

A

10 million in need of food assistance

105
Q

what is the definition of a heatwave

A

“A period of high temperatures relative to typical seasonal conditions for a location”

106
Q

what are rips currents

A
  • Strong, localised currents that flow perpendicular to the coast
    • Flows within rip currents can reach 2 m/s
    • Identifiable as areas of calm water cutting across breaking waves
    • Globally, rip currents are the primary physical hazard impacting on recreational beach users
107
Q

how do rip currents form

A
  • Dependant on beach morphology
    • Typically associated with sandbars
    • Waves break as they hit shallow water overlaying sandbars (1)
    • Water then flows “downhill” into deeper areas where there are no sandbars (2)
      Water flows back out to sea in the deeper channels between sandbars (3)
108
Q

what type of rip currents are there

A

Boundary Rips
Bathymetric Rips
Hydrodynamic Rips

109
Q

how big is wales coastline

A
  • Wales has a coastline of 1,680 miles

The Welsh coastline has c. 200 beaches

110
Q

what are the common reasons people are caught in rip currents

A
  • We let our guard down on holiday.
    • We like to show off to our peers.
    • We don’t swim on lifeguarded beaches.
    • We visit lifeguarded beaches out of hours.
    • We over estimate our swimming ability.
    • We underestimate our sobriety.
    • We don’t understand the danger.
    • We panic in dangerous situations.
    • We don’t know how to escape the current.
      We don’t normally live near the seaside.
111
Q

what are the rip current misconceptions

A
  • Rip currents drag you under the water.
    • Strong swimmers can “out-swim” rip currents.
    • Rip currents are easy to spot.
    • Rip currents only happen in bad weather.
    • Calm water is the safest place to swim.
    • Rip currents will sweep you far out to sea.
      Personal Intention vs Action.
112
Q

mitigating rip currents

A
  • Understanding different kinds of rip currents and their formation.
    • Understanding the impact of seasonal tides and changing beach morphologies.
    • Developing current forecasting systems.
    • Understanding people and their behaviours.
    • RNLI image recognition research.
      GPS drifters (Pitman et al. 2016).
    • 39 Welsh beaches have seasonal Lifeguard stations.
    • In 2021 the RNLI aided 35,247 people in 3 months.
      XXX people are caught in rip currents in Wales and the wider UK.
113
Q

how many people were rescued from rip currents in the uk

A
  • 2006 – 2011: 12,607 people were rescued from 5798 rip current incidents.
    • 2006 – 2011: Southwest England and Wales accounted for 94% of all UK rip current incidents (Woodward et al. 2013).

83% of respondents escaped a rip current without any assistance (Drozdzewski et al. 2012)

114
Q

TRUE or FALSE, rip currents incidents increased post covid

A

TRUE

115
Q

how often do 10km impact event happen

A

every 100 million years

116
Q

how often do super eruption happen

A

10,000 - 100,000 years

117
Q

what are evidence terms for super events

A
  • Low-frequency high-magnitude
    • Past experience  ~100 y
    • Instrumental records  ~150 y
    • Historical records  ~1000 y
    • Archaeology  ~10,000 y
    • Anthropology  ~50,000 y
    • Quaternary  2 Ma
      Geological record  4,000 Ma
118
Q

describe super volcano evident of MT. St Helen, 1980

A
  • Debris avalanche 2.5km3
    • preceded eruption
    • ~2.5 km3
    • overtopped 360 m ridge
    • flowed 21 km
      100-200 km/h

Normal behaviour
* Weakened by:
Weathering
weak materials
* Triggered by:
Earthquakes
pore-water pressure
sea-level change

119
Q

what was the largest volcano eruption in the last 2 million years

A

73,500 BP
2,000 - 2,800 km3
Caldera 100x30 km ( Now a lake )

Created a “volcanic winter”
Sunlight to 10%
Global drop 5°C
For ~10 y
1000 y cooler

120
Q

give an example of mega hazard comment hitting earth

A

Example, Tunguska, Siberia, 1908
* Explosion
 trees flattened over 2000 km2
* Fires
Not visited for 19y after event

121
Q

effects of asteroid impacts

A

Depend on:
* Size
* Target
land  debris in atmosphere
sea  giant tsunamis
* Velocity
energy (v2)
NEOs 15-22 km/s
long-period comets >50 km/s

122
Q

list the terms and size of asteroid with their level of hazard

A

50m - destroy city (airburst)
150m - destroy small country
1000m - global effects; 20km crater
5000m - mass extinction

123
Q

what are the mitigation and response strategies to asteroids

A

Mitigation:
Observation + Tracking
* Telescopes
* Difficult to find
* NASA catalogues
NEOs >1km
* 840 discovered;
150 PHAs
* Smaller objects?
* Chelyabinsk undetected

Response:
* Do nothing
* Destroy/disrupt:
Explosives
Unpredictable
Last resort
* Slow deflection
Solar sails
Engines
Mass drivers

124
Q

what are types of floods

A

Flood: a temporary inundation of normally dry land by water
* Fluvial (river floods)
* Pluvial (rainfall-induced flash floods)
Coastal (storm surge)

125
Q

what are ice jams

A

River freezes, and thaws, and then will jam under bridge of dam, causes floods further up the river

126
Q

list the terms and definitions for floods

A

drainage basin - Drainage basin conditions (hydraulic geometry, size of basin) determine speed of flood onset, flow velocity, peak flow and event duration.

* Floodplain
 The relatively flat landform adjacent to a river channel composed of alluvium and subject to episodes of flooding

* Floodway  Part of the floodplain where there is rapidly flowing water in times of flood. The remaining is slackwater.
127
Q

what are the flood-prone evironments

A

Flood-prone environments
* Low-lying parts of major floodplains (e.g. Bangladesh)
* Low-lying coasts and deltas (e.g. Vietnam)
* Basins subject to flash floods (e.g. Kuala Lumpur, Malaysia)#
* Areas below unsafe or inadequate dams (e.g. Derna, Lybia)
* Low-lying inland shorelines (The Great Lakes, USA)
Alluvial fans (arid American West)

128
Q

whats the equation for recurrence intervals

A

RI = (n+1)/m
RI is based on probability (P)
P=(m/(n+1))x100

129
Q

what hazard has urbanisation increased

A

flooding, the more concrete and less ground causes less shallow infiltration and more run off

130
Q

describe the primary, secondary hazards and long term effects of flooding

A

Primary hazards
* Damage and loss of property and infrastructure
* Sediment deposited
* Loss of crops and livestock
* Drowning
Secondary hazards
* Drinking water quality
* Disease (e.g. cholera, typhoid)
* Mental health (e.g. stress, anxiety)
* Services disrupted
Long-term effects
* Insurance rates increase
* River channels change
Agricultural land destroyed?

semester 2 flash cards (3 decks)

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