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MOCK CASE STUDIES PHYS-HAZARDS

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Hurricane Maria: the third major Atlantic hurricane of the 2017 season
1. Track of the tropical storm
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Hurricane Maria pushed north-west through the Caribbean. Hurricane Maria progressed as time went on
strengthened and by September 17th, Maria’s winds doubled from 85mph, a Category 1 hurricane, to
165mph, a Category 5 hurricane in just 24 hours.
2. Causes of the tropical storm
What were the meteorological conditions like at the time eg sea temperatures, pressure systems, wind
shear?
Hurricane Maria originated from a tropical wave that left the western coast of Africa on the 12th September, it
then progressed eastwards across the tropical Atlantic and by September 16th, it had developed into a
tropical depression.
Favourable conditions allowed the system the disturbance to become Tropical Storm Maria, with the
system’s path consisting of surface sea temperatures of 29oC, low wind shear and abundant moisture.
Many experts would argue climate change has contributed to events like Hurricane Maria, saying that the
rising temperatures are leading to warmer air holding more moisture which in turn, causes more intense
downpours and that as a result or rising oceans, due to thermal expansion and glacier melt, there has been
an increase in the dangers of storm surges.
3. Hazards caused by the tropical storm
Hurricane Maria’s outer rain-bands produced heavy rainfall (75-125mm) and strong gusts across the
southern Windward Islands, the heavy rainfall lead to a series of floods due to the volume of water bursting
the banks. Whilst the strong gusts of wind caused problems with powers.
4. Impacts of the tropical storm
In total, 112 people died and 104 went missing.
Overall, Maria’s destruction has caused as much as $94 billion in damage for the already indebted island,
with 90% of properties being damaged in some way.
For months, 90% of households were without electricity, cell phone service was limited with clean water,
food, medicine and fuel all in short supply too. The main general hospital was also compromised, causing
patient care to suffer.
In terms of infrastructure, landslides and uprooted tress caused minor damage and leading to the blocking of
some roads; the strong winds resulted in roofs being ripped from buildings, the faltering of buildings,
Whilst heavy rainfall resulted in rivers bursting their banks causing scattered flooding across Barbados,
whilst the hurricane causing rough seas also resulting in the flooding of coastal sidewalks and the damage of
boats.
The agriculture industry was also affect, in particularly the banana industry, suffered loses as a result of the
winds.
5. Mitigation of the impacts
• The National Hurricane Centre first advised about what would later become Tropical Storm Maria on the
16th September, so the government of Barbados issued a similar watch for Dominica. All before the NHC’s
second advisory, which declared Maria a tropical storm.
How were people warned?
• Evacuation orders were issued in Puerto Rico in advance of Maria, officials also announced the opening of
450 shelters which, as of the next day (September 19), at least 2,000 sought shelter, showing that the
population did listen to the warnings.
Were people and authorities prepared? Did anything go wrong? Why/why not?
• People boarded up their homes, businesses closed and the majority of families only went out for
essentials.
Mitigation of the impacts
As of 11 October, 50 expert missions had been sent to 11 countries and territories of the Caribbean.
In order to resume operations in health facilities, support was provided to strengthen the capacity of national
authorities to assess damages in hospitals.
6. Factors influencing the impacts of the tropical storm
The extent of impacts of Hurricane Maria Hurricane depended on the state of the area beforehand.
So, for example, Puerto Rico was still recovering from Hurricane Irma two weeks prior, which had left 80,000
without power as Maria approached. Furthermore the island was already facing an economic collapse. Other
factors included Puerto Rico’s ageing infrastructure, making the island more susceptible to damage from
storms, which is the main reason why over one million people were without power.
Venezuela 1999
1. Debris flows and landslides have taken place in Vargas, Venezuela.
The 1999 disaster occurred when torrential rain caused flash flooding followed by
debris flows, which saturated the soils and the formation of water ponds on the
surface, leading to the triggering of numerous shallow landslides that stripped soil
and rock off the landscape and sent them sliding down slopes. Additional water
liquified these landslides into debris flows.
2. Causes
Natural factors
Human factors
The very steep mountains behind the narrow coastal The coastal area had become densely populated
strip have many slopes steeper than the angle of
and urbanised.
repose/critical angle for loose material.
December 1999 was extremely wet-911mm fell in 52 The area consists of marginal land due to the
hours-equivalent to a year’s average rainfall.
steepness of the land. Over the years, shanty towns
and spontaneous settlements have sprung up with
This storm was unexpected as it occurred in
minimal or no planning meaning a subsequent lack
December, rather than during the typically rainy
of facilities like drainage. The corrupt government of
season in coastal Venezuela.
Venezuela could potentially partly to blame for the
impact of the mudflows as without the shanty towns,
This abundant rainfall triggered soil instability and
fewer people would have been killed.
flows of debris.
The surrounding area’s bedrock is mainly
metamorphic: metamorphic rocks have planes of
weakness along which the landslides will occur
where they are inclined towards lower areas.
Removal of vegetation: the slopes had lost their
protection and stability because trees had been
cleared by the local people also the trees were no
longer there to intercept the rainfall.
This removal of vegetation was done in order to
make room for urban development, in particular,
shanty towns.
Many of the coastal towns were built on old debris
flows.
3. Hazards caused
Debris flows
4. Impacts of the tropical storm
- These debris flows killed tens of thousands of people, as much as 10% of the population of Vargas died in
the single event in December 1999.
• The death toll is considered to be between 10,000-30,000, however it is difficult to determine due to
there being no reliable census data.
- Houses were destroyed: a high percentage of houses were swept into the ocean and the debris flows
themselves destroyed thousands of homes. Overall, it is estimated that the buildings destroyed in Vargas
displaced up to 75,000 people.
• The destruction of homes left many homeless and led to the complete collapse of the state’s
infrastructure.
- The most severely affected areas were the shanty towns on the edge of Carcas and the settlements in the
state of Vargas.
- The disaster caused estimated damages costing $1.79-3.5 billion.
- Public services including water, electricity, phone lines and roads and bridges completely disappeared in
some places. This meant that for months there were no supplies of food and water and therefore the
majority of the population had to be evacuated.
- Airports were also closed for several days.
- Looting and sacking occurred everywhere, forcing the military to implement martial law for more than a
year.
5. Mitigation of the impacts
- The first response was the evacuation of survivors, ultimately, more than 100,000 people were evacuated.
- Due to the lack of transport links, the days immediately following the disaster, food, shelter and medical
help were in short supply.
- Due to the amount of displaced people, the Venezuelan President, Hugo Chávez, encouraged other
Venezuelans to open up their homes and to ‘adopt a family’.
- The disaster has also shown that the importance of planning urban developments more carefully in the
future, for whilst, the natural factors triggered the hazard, the population should have never been allowed
to occupy such potentially hazardous hillsides.
6.
- In conclusion, the intense rainfall and marginal land triggered the rapid and hazardous debris and mud
flows. Whilst human impacts, like the removal of vegetation, just contributed to the problem, and
increased the impact of the event.
- Because the intense rainfall and marginal and mountainous land triggered the flows, I would argue that
these are the main factors of the event and therefore that physical
factors, more so than human factors, were to blame for the
disaster.
- Whilst the human factors simply accelerated the time taken and
increased the damage done, which follows the idea of Degg’s
model: the population of Venezuela’s vulnerability increased the
severity of the event. After all, without the building of shanty towns
of marginal land, fewer people would of been homeless.
Haiti Earthquake
1.
An Earthquake occurred in Port-au-Prince in Haiti on January 2012 with a magnitude of 7, with a focus depth
of 13km ultimately resulting in the death of around 200,000 people.
2.
Main cause
The earthquake resulted from a tiny fragment of the Caribbean plate moving eastwards, a long a fault in the
destructive plate boundary with the North American plate.
The shallow depth of the movement caused much damage from shaking, which lasted for almost a minute.
3. Hazards caused
- Liquefaction: much of the city was built on loose sediment, which allowed the amplification of seismic
waves.
- Shaking
4. Impacts of the tropical storm
- 200,000 people were killed, although this is an estimate since people were buried quickly in mass graves
to reduce the incidence of disease meaning record-keeping was difficult.
- More than 100,000 are estimated to have been injured whilst up to 1.5 million were left homeless.
- Buildings: hospitals and government buildings were destroyed alongside 250,000 residences and 30,000
commercial buildings.
- Aid: incoming aid was delayed because the international airport’s control tower and the port were
destroyed, many roads were also blocked.
- Looting and violence proved problematic for relief workers when trying to keep stocks of food and water
safe and distribute them.
- More than 3000 died in 2010 due to cholera outbreaks caused by the poor sanitation in the temporary
tented camps. These outbreaks continued to 2015, killing a total of 8600 people.
- Despite the extensive scale of the devastation, the economic cost of the earthquake was relatively small,
less than $US 9 billion. Few people were insured against losses however, so the biggest cost was
rebuilding.
5. Mitigation of the impacts
- Aid
• The international airport had only one runway, limiting the number of planes carrying aid and aid worts
that could land.
• Haiti had no army and few emergency service vehicles or staff to give immediate assistance.
- Recovery
• Haiti had poor residence as recovery was largely dependent on overseas aid.
• Three years after the earthquake, just over half the debris had been cleared and about 280,000 people
stilled lived in camps (some of which were without flushing toilets.)
• One fifth of the population lost their jobs because clothing factories, the largest employer, had been
destroyed.
• Because few people were insured against losses, the biggest cost was rebuilding.
6. Vulnerability, risk perception…
- Reasons for the severity of the earthquake
- It struck the densely populated capital city.
- Haiti is a very poor country and is without building regulations, so most infrastructure has been
constructed cheaply: buildings weren’t reinforced and many had no foundations, heavy concrete
buildings collapsed because they had insufficient steel in their support columns.
- Many people lived in shacks made of flimsy material on very steep, unstable slo[es/
- Risk perception
• The earthquake was unexpected and the country was unprepared because the last earthquake which
caused damage was in 1770.
The Tohoku (Sendai) Earthquake and Tsunami, Japan 2011
1.
The 9.0 magnitude earthquake occurred at a depth of 32km off the north-east coast of Honshu, Japan’s main
island.
The tsunami affected at least 2000km length of densely populated coastal lowlands.
2.
Main cause of the earthquake and tsunami
The Pacific plate begins to subduct beneath the Eurasian plate at the rate of 83mm per year.
Thrust-faulting uplifted the sea floor by 35m.
3. Hazards caused
- The earthquakes caused fires in all the affected cities and in an oil refinery.
- Tsunami: the tsunami proved the most lethal factor of the earthquake. Occurring only 129km from the
coast with wave heights of around 10m. Inundating 561 km2.
4. Impacts of the earthquake and tsunami
- The tsunami inundated 561 km2 and destroyed 100 tsunami evacuation sites.
- The total death toll was 20,896, with more than 5,000 injured and 130,000 homeless.
• Most of the deaths were caused by the tsunami (this was because, the tsunami followed the earthquake
too rapidly for adequate warning to be given.)
- Infrastructure: approximately 332,000 buildings, 2000 roads, 55 bridges and 26 railways were destroyed or
damaged.
• A dam also collapsed near Fukushima, destroying 1,800 homes.
• Most casualties and damage occurred in the cities of Iwate, Miyagi and Fukushima.
• Damage to buildings and supply lines caused major industries, including Toyota, Honda and Nissan to
halt production.
- Millions of homes were without power as the Fukushima nuclear power station had to be closed down after
being severely damaged causing partial meltdown and radioactive leaks. The damage was so severe an
evacuation zone had to be created around the station, lasting for over 3 years later.
- Japan’s total economic loss was estimated to be more than $US 300 billion, making it the costliest disaster
ever.
5. Mitigation of the impacts
- Recovery
• Severe damage to the infrastructure made rescue and recovery immensely difficult but the relief
mission was so enormous that, three years afterwards, most of the debris had been cleared, although
people were still living in temporary housing.
6. Vulnerability, risk perception…
- Risk perception/Preparation
• Nobody in who world was better prepared for earthquakes but the sea defences proved totally
inadequate with no one imagining waves as high as 10m would occur (with a wave reaching nearly
38m high hitting Miyagi).
- Furthermore because the tsunami occurred so soon after, they had no time to evacuate etc.
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