Hazardous Environments: A Comparison of The Impacts of Tropical Storms, in An LIC and An HIC
Hazardous Environments: A Comparison of The Impacts of Tropical Storms, in An LIC and An HIC
Hazardous Environments: A Comparison of The Impacts of Tropical Storms, in An LIC and An HIC
A natural hazard is a natural event with the potential to harm people and their property. A
natural disaster is the realisation and impacts of a natural hazard, i.e. the deaths, injuries,
disruption and damage. The EM-DAT international database (www.emdat.be/) suggests a
hazard becomes a disaster when at least one of the following criteria is met:
10+ people are killed.
100+ people are affected.
A state of emergency is declared.
International assistance is called for.
Task: look at the list of events below and decide whether they are a Natural Hazard or not,
make sure you explain why:
A cyclone that hits an uninhabited island
An earthquake in a mountainous region
An earthquake in a densely populated Urban Area
Term
Distribution
Frequency
Scale
system, clouds, moisture, heated, storm, dies, loses, heat, rising, water, towards, energy,
land, circle , storm, fuel, Air, earth, blow
Tropical Storms, what and where:
Tropical Cyclones are known by different names around the world (see the map below),
these are:
North Atlantic: Hurricanes
Pacific: Typhoons
South East Asia: Cyclones
Australia: Willy-Willies (Cyclones)
Task: Describe the movement of the different storms around the world.
In essence there is little difference between the different storms, Typhoons often drop a lot
more water than Hurricanes but this is only to do with where they form not differences in
why they form.
The sequence of events as a tropical storm travelled overhead:
Task: Put the statements in order from 1 5 of what the conditions would be as the storm
passed overhead.
1. The eye of the storm is overhead. Skies are clear, the temperature and pressure increase, and the
wind dies down. Unfortunately this is only a brief lull in the storm.
2. The storm hits again. Temperature and pressure falls. Torrential rain and wind speeds of over
100km/hr occur. The winds are now coming from the opposite direction than they were before.
3. After the storm the temperature and pressure rise again. The rain becomes showers, and the winds
die down. The cleanup operation begins.
4. As the storm approached there would be a drop in temperature and pressure. Wind speeds would
begin to increase and clouds would form
5. As the storm is overhead the pressure would fall rapidly, as would the temperature. Wind speeds
would be in excess of 150km/hr and the rain would be torrential. The wind would whip up waves that
could swamp entire coastal areas, or drown entire coral islands in the Pacific.
Order:
Structure of a Hurricane
Tectonic Plates
Info: the crust is broken up like a jigsaw puzzle into a series of tectonic plates, the map
above shows the most famous and largest ones. These boundaries are not exact, you have
to imagine a plate is like a cracked pane of glass, there is not just one crack, but many
smaller splinters and fractures (these are often known as fault lines). The plates are sections
of the crust that "float" on the mantle (they dont but it is good way to think of how they are
able to move), which is made up of molten rock. Where the plate's meet, huge forces mean
that they can form features such as volcanoes, Fold Mountains, deep-sea trenches and rift
valleys. The result of the meeting of these plates can be very destructive.
There are two main types of tectonic plate. Oceanic crust is often only about 5km thick, but
is very dense. Continental crust is considerably thicker, often being approximately 30km
deep, but is less dense.
Convection Currents
The Earth's Tectonic Plates all move very slowly on the mantle, meeting along the four main
boundaries that can be found in the next section. The plates move due to convection
currents in the mantle. These are hot currents of molten rock that slowly move within the
mantle and cause the plates above them to move, usually by as little as one or two
centimetres each year.
Task: what plate boundary types
may you find at each point
A:
B:
C:
Explain why:
These cause violent volcanoes and earthquakes, as well as deep-ocean trenches and
fold mountains.
An oceanic plate and continental plate move towards each other
The denser oceanic plate dives under the lighter continental one, creating a deep
ocean trench
As the oceanic plate goes deeper into mantle it melts in the subduction zone, due to
friction and the increased temperature.
The newly molten rock is lighter than that which surrounds it, so it will rise towards
the surface and cause volcanoes on the earth's surface
The continental crust is crumpled by the collision of the two plates creating Fold
Mountains.
If the magma rises offshore it will form an Island Arc, like the West Indies and Japan.
A good example of a destructive plate boundary is where the Nazca plate dives
underneath the South American plate. This has caused volcanoes, earthquakes and
the formation of the Andes Mountain Range.
Constructive Plate Boundaries (Also known as divergent or tensional boundaries)
The main effects of a conservative plate boundary are earthquakes, which can be
fairly violent and frequent.
Two plates slide past each other, without creating or destroying any land.
As they move past each other they often get stuck, building up great pressure until
finally they jolt past each other. This sudden movement is what causes earthquakes.
The best-known example of a conservative plate boundary is the San Andreas Fault,
where the North American and Pacific plates are actually moving in the same
direction, but at a different speed.
Collision Margins
Often this movement and pressure can cause earthquakes, but no volcanoes will
occur on these boundaries.
The best example is found where the Indian plate collided with the Eurasian plate to
form the Himalayas.
Task: Use the descriptions to draw an annotated diagram to show how each of plate
boundaries work:
Destructive:
Conservative:
Collison:
Constructive:
Volcanoes
Info: Volcanoes occur when magma is forced to the surface through cracks and fissures in
the Earths crust. Explosivity depends on magma viscosity. The more viscous the magma,
the more hazardous the volcano as it causes the explosive power to rise. Viscosity depends
on temperature, gas and silica content of the magma in the magma chamber. Highly
explosive volcanoes erupt low temperature, viscous lava with a high silica content.
Volcanoes are often places of multiple hazards.
Classic Cross Section of a Composite Cone Volcano
Types of Volcanoes
Volcanoes are formed along two types of plate boundary: destructive and constructive
boundaries. The basic shape of a volcano is similar throughout the world; however there are
many factors which influence how the volcano is built. Volcanoes occur where molten rock
(magma) is allowed to escape to the surface of the earth. This usually occurs at plate
boundaries through cracks in the crust called vents.
Once it has reached the surface, the magma becomes known as lava. The composition of
the lava determines the shape of the final volcano.
Volcanoes also throw out ash, steam, dust, pumice, and gases, which can be poisonous.
However it is the lava that mainly helps to shape the volcano.
Type
There are three main volcanic cones: acid lava cones or Dome, Composite Cones and Basic
lava Cones/Shield.
Task: Match the heads with the tails for the different types of volcanoes
Description
Example
Acid cone/Dome
Volcano
Composite Cone
Volcano
Basic Lava
Cone/Shield
Volcano
Task: Name the different types of volcanoes and add the correct labels to the third one.
Earthquakes:
Info: Earthquakes are shock waves that occur when tectonic activity causes the ground to
shake occur along faults, which are large cracks in the earth's crust. Most of these are
associated with the larger plate boundaries, along which the largest earthquakes usually
occur. They are caused by the sudden jerking movements of the fault, either laterally or
vertically, and are almost impossible to predict.
They most commonly occur when two tectonic plates move suddenly against each other.
Rocks fracture underground at the earthquake focus and the Earths crust shakes as energy
is released. Waves spread from the epicentre, the point on the surface above the focus.
Severe earthquake damage can occur when unconsolidated sediment undergoes a process
called liquefaction. This is often responsible for the worst ground shaking and damage.
The point at which an earthquake actually begins, deep below the earth's surface is called
the focus. If the focus is deep then the effects of the earthquake may be less as the
shockwaves have more rock to move through. Obviously this also depends on what type of
rock it is. The point directly above the focus, on the earth's surface, is called the epicentre.
The effects of the earthquake are usually worst here, and then radiate out from this spot.
Effects of Earthquakes
The effects of an earthquake can be easily split up into two sections. Primary effects are
those that occur immediately as the earthquake happens. These include buildings
collapsing, roads and bridges being destroyed and railway lines being buckled. All occur due
to the shaking of the ground.
Secondary effects are the subsequent effects of the quake, and can be even more
devastating than the primary ones. The main secondary effects are:
Fires: usually from ruptured gas lines. This was the main cause of death and damage
after the San Francisco earthquake in 1906.
Tsunami waves: A tidal waves caused by an earthquake is called a tsunami. They
can travel very quickly across entire oceans, before engulfing land 1000's of miles
away. The 1964 Alaskan earthquake caused considerable damage in several
Californian coastal areas. Although Los Angeles has escaped so far, it is still
considered to be a tsunami hazard prone area.
Landslides can often be triggered by earthquakes, causing huge amounts of
material to be moved very quickly. This is actually what occurred just before the
volcanic eruption on Mt. St. Helens. They are most likely to occur where the land is
steep, saturated or weak.
Diseases can spread very quickly in the unsanitary conditions often left behind by
massive earthquakes. Water becomes contaminated very quickly, and in Less
Economically Developed Countries (LEDC's) especially; access for the medical
services can be badly hampered by the damage caused by the quake. The most
common diseases to be associated with earthquakes are therefore water-borne ones
like cholera and typhoid.
Task: for the effects in the paragraphs above, making sure you use some examples to help
explain you reasons, discuss the relative size of impact they are likely to have (time scale,
numbers impacted etc)
kilometers of material and have a cloud column height of over 25 km (16 mi). The scale is
logarithmic (from 1 -8) with each interval on the scale representing a tenfold increase in
observed eruption criteria.
In recent history examples are:
2010: Icelandic eruption of Eyjafjallajkull was a VEI 4 eruption
1980: Mt St Helens (USA) was a VEI 5 eruption
Mauna Loa on Hawaii due to being constantly erupting is a VEI 0
Task: What are the benefits and drawbacks of the different ways of measuring tectonic
activity
Preparation of
Population
Communicatio
n Networks
Emergency
Services
Scale (size
and strength)
Location
Frequency
Supplies of
Water and
Food
Disaster
Planning
Rural v Urban
Experience
Relationships
with overseas
countries &
NGOs
Time of Day of
hazard
Season/time
of year of
hazard
Frequency
by floods, but these were in short supply. Many of the unidentified dead were buried in
mass graves or their bodies were cremated.
In some areas, whole villages were washed away and an estimated 70-80% of roads/railways
were destroyed. The majority of the country's bridges were damaged or destroyed. Even
airports were under water. Fuel, electricity and running water became scarce commodities.
Damage was so severe that it was calculated that it could take 15-20 years or more to
rebuild the country. One third of all buildings in the capital were damaged by the floods.
Survivors were still clinging to roof tops a week or more after the storm. Heavy damage was
caused along the coastline and off-shore islands by the storm surge and hurricane-force
winds. Tourist resorts along the coast were seriously damaged. The estimated damage to
roads and buildings in Honduras was $4 billion.
At least 70% of the crops on farms were destroyed, including almost all of the banana crop.
Crop losses were estimated at $900 million. Further damage was caused by the flooding of
the large warehouses and storage rooms used for coffee beans. The damage by Hurricane
Mitch to Honduran farming will take many years to put right.
NICARAGUA:
Northwest and northern parts of the country were most affected. An estimated 3800 people
died with perhaps as many as 7,000 others missing. Between 500,000 - 800,000 people
were made homeless. Intense rain over western Nicaragua on October 29th-30th caused
over 600mm of rain to fall (about one years rainfall in south-east England!). The crater lake
on top of the dormant Casita volcano filled up and part of the walls then collapsed on
October 30th, causing mud flows that eventually covered an area ten miles long and five
miles wide. At least four villages were totally buried in the mud that was over a metre deep.
Over 2,000 of the dead were from the areas around the collapsed volcano. In many cases,
survivors had to wait days before the mud had dried enough to walk to rescuers. Damage
was serious from flooding in other parts of the country, also. On November 5th, 500 bodies
were found in the Coco River near the town of Wiwili. An additional 500 unidentified bodies
had washed up on the Pacific shore after flood waters had washed their bodies out to sea. As
with Honduras, there were serious food and water shortages in flooded areas. The
roads/railways and all forms of communication in the affected regions were devastated. Over
30% of the coffee crop was destroyed and there was serious damage to the bean, sugar, and
banana crops. Damage estimates for Nicaragua were $1 billion.
EL SALVADOR
The western part of the country was most affected by the heavy rain. 230 people died and
500,000 were forced from their homes by the flooding. As much as 80% of the maize crop
was lost. Coffee plantations and the sugar cane crop was severely affected.
GUATEMALA
Over 200 people were killed by the floods. Ten U.S. citizens and one other person was killed
in a plane crash supplying emergency aid on November 1st. Nearly 80,000 people were
evacuated from their homes because of the flooding. There was widespread damage to the
coffee and banana plantations.
Case Study 2: Tropical Storm in HIC Hurricane Floyd 1999
Human effects
79 people died
4 million people left their homes in Carolina, Georgia and Florida
1 million people lost electricity & water supplies
12,000 houses destroyed
150,000 people registered for government assistance
Hurricane Floyd left the downtown area of Franklin, Virginia under 1.8metres of water
Economic effects
$460 billion paid out for insurance.
Farmers lost $1 billion
Many farmers had to find other jobs as crops totally destroyed
250 roads and many bridges damaged
In Bahamas; boats, hotels and offices destroyed as well as houses.
Environmental effects
Beaches & sand dunes destroyed
Oak Island had 20m of beach blown away
1000s trees blown down
Severe erosion at Barrier Islands which led to increased flood risk on coastline
14 states suffered from flooding. North Carolina had area size of Belgium flooded.
-
coastal flooding
Case study of
management hurricane Floyd
Low pressure and high tide caused a storm surge of 3 m meters. Due to high rainfall, rivers
were 7 meters above normal.
The satellite technology predicted the storm. A hurricane watch and warning was issued
and a coastal evacuation took place. This was well organised by the government and only
51 people drowned. 2.5 million people were moved. The government gave 2 billion dollars
of aid to help people rebuild damaged houses. People were also able to claim on insurance
policies.
Sea walls protected some areas from storm waves. Also, some houses are built on stilts to
prevent them from being damaged by storm surges
Evacuation.
Volcanic activity has calmed down in recent years and people have begun to return to the
island.
energy
Tourism
Scenery
Economic
restrictions
Land Value
Choice (studying
them)
Optimism of
things getting
better
Health Care: HIC's have the medical resources and money to quickly get
appropriate aid to areas after a natural disaster. MIC/LIC's often have to rely on aid
from overseas as their health system, which is inadequate. This overseas aid takes
time to arrive, which could mean far more casualties.
Emergency Services: In HIC's who have a volcanic or earthquake risk, such as
Japan and New Zealand, there are well thought out emergency procedures. Practices
in schools and places of work mean that people know what to do it the event of a
natural disaster. The Government's and military have special emergency plans to
help with the situation.
Often MIC/LIC's do not have these emergency plans, and so (as seen in the Asian Tsunami of
2004) far more damage can be done before the emergency services reach the stricken area.
Building Technology: Countries such as Japan and the United States have been at
the fore front of developing buildings that have more chance of resisting an
earthquake. Most houses in San Francisco are made of wood, to make them more
flexible and allow them to move with the quake. Larger skyscrapers are built with
flexible foundations, which literally allow them to sway during a quake, rather than
being rigid and falling down. Many countries in areas prone to natural hazards have
building codes to say where they can and cannot build, and how high the buildings
can be. New Zealand is a good example of where this occurs. LEDC's don't tend to
have the technology available or money to pay for it, and soften their buildings are
very susceptible to earthquakes. One example was the Armenian earthquake in 1988,
which was 0.1 less on the Richter scale than Kobe, but killed 20,000 more people.
Most of the Armenian houses were built of stone and so collapsed instantly.
Scientific Prediction: Scientists work throughout the world, trying to predict
earthquakes and volcanoes. So far they have found it very difficult to predict
earthquakes, although scientists monitoring the San Andreas Fault in California have
planted a huge number of seismographs in the ground to try to detect even the
faintest of tremors. Volcanoes generally are easier to predict, although the specific
time of the eruption is not so easy to do. Scientists can measure changes within the
mountain that helps them to predict that the volcano is going to erupt. This usually
allows the Local Authorities sufficient time to evacuate people from the danger area
(as seen at both Mt. St. Helens and Mt. Pinatubo). However they still find it very
difficult to accurately predict the size of the eruption. HIC's do tend to have more
investment for this type of research and development than MIC/LIC's.
Recovery: HIC's tend to be able to recover quickly from a natural disaster, due to
having the investment and technology needed to return the area to as good as new
as soon as possible. Because MIC/LIC's often have to rely on aid from overseas, this
quick recovery is often impossible for them.
The earthquake that devastated the Haitian capital of Port-au-Prince on 13 January
also affected many outlying towns - the extent of which is only being discovered days
after the disaster.
Analysis and reports from international agencies have helped provide a picture of
how badly hit other areas were.
The epicentre of the magnitude 7 quake was south west of Port-au-Prince and large
towns in that region, such as Leogane, Gressier and Carrefour suffered large
scale destruction, with up to 90% of buildings destroyed in some places.
In Leogane, between 5,000 and 10,000 people were killed.
Smaller towns in the area also suffered.
In Jacmel, on the southern coast, more than 3,000 people were reported to have
been killed or injured and 60% of buildings damaged or destroyed.
12th January 2010 at 16.53 (about tea-time) local time, It was a 7.0 magnitude earthquake.
But as we know this only tells as the size of the earthquake not the damage it does.
Impacts
217,000230,000 dead
300,000 injured
1,000,000 homeless
250,000 residences collapsed or severely damaged
30,000 commercial buildings collapsed or severely damaged
This is a big earthquake, but why were the number so high?
Summary: reasons why the earthquake was so severe Original thoughts:
the proximity of the city to the fault that caused the shaking,
shoddy construction that allowed thousands of buildings to easily crumble
the nature of the rock, being sedimentary, carried the vibrations further and with
greater amplification (bigger waves)
Summary: reasons why the earthquake was so severe recent findings:
A narrow ridge of hard rock seems to have vibrated even more than expected this
are contained better built hotels/businesses which were still really badly damaged.
Until recently these anomalies had been known about but written off an
unexplainable flukes
These findings will help plan which areas should be redeveloped and which should be
avoided microzonation maps
The only single seismometer on Haiti was an educational instrument that was set up
wrong quote scientist. . When the earthquake happened, it went dancing around
on its little feet, she said. It did make a record, but it wasnt very useful. They now
have 8 on the ridge and on the sedimentary rocks correctly installed!
Using examples you have studied, explain how coastal flooding can
be managed (9)
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