Download Natural hazards such as earthquakes, floods, hurricanes, droughts

Natural hazards such as earthquakes,
floods, hurricanes, droughts and
volcanic eruptions are rarely out of the
news. Every year they are responsible
for many deaths and serious injuries,
they destroy livelihoods and damage
economies. Scientists predict that
climate change will affect the frequency
and severity of some natural hazards.
Most natural hazards cannot be
prevented but by understanding how
and where they occur, what causes
them, and what circumstances increase
their ferocity, we can develop effective
strategies to reduce the damage
they cause.
The Natural Environment Research
Council (NERC) is the UK’s leading
environmental research organisation.
NERC scientists advise the UK
government on ways to minimise the
risk of natural hazards.
In this briefing note we look at some
major natural hazards and what risks
they pose to life, the economy and the
environment.
◗ Volcanoes
◗ Earthquakes
One in ten of the world’s population live close to active or
potentially active volcanoes.
Earthquakes can occur anywhere but major earthquakes
tend to happen along fault lines in the Earth’s crust.
On average 50-60 volcanoes are active each year. Around 1,500
volcanoes have been active in the last 10,000 years.
Although there are thousands of earthquakes each year only
a few damage towns or cities.
Volcanoes rarely erupt without warning, but scientists monitor
only a few of the world’s volcanoes.
The British Geological Survey
registers 200-300 small
earthquakes a year in the UK.
Constant monitoring greatly reduces the death toll when a
volcano erupts as exclusion zones are usually very accurate.
The main hazards associated with volcanoes are: lava flows,
pyroclastic flows (fast moving hot rocks and debris), explosions
and mudflows. Secondary hazards include tsunamis and
changes to regional and global climates causing temperature
drops, famine and disease.
Fine volcanic ash can stop a jet engine.
In 1988 scientists suggested there would be an increase in
volcanic activity on the Caribbean island of Montserrat
sometime in the mid-1990s. The volcano erupted in 1995 but
good monitoring procedures meant fatalities were few, though
damage to the surrounding area was extensive.
Volcanic eruptions have far reaching effects on regional and
global climate. All eruptions throw huge clouds of sulphur
dioxide gas into the atmosphere. When Pinatubo in the
Philippines erupted in 1991 a plume of gas spiraled into the
atmosphere and enveloped the planet, lowering temperatures
by about 0.25 degrees centigrade for a few weeks.
Volcanic activity is not entirely random. It is often seasonal,
suggesting that environmental factors such as weather, climate
and sea level influence volcanoes. The volcano on Montserrat
seems to have a tendency for large eruptions in summer, maybe
because of increased rainfall.
There is still no reliable way to
predict earthquakes despite 40
years of research, but statistics
and geological knowledge can
indicate where large
earthquakes are likely and what
their effects will be.
Many major earthquake zones
such as California and Japan
An earthquake reduced the town
are extremely well monitored.
of Bam in Iran to rubble in 2003.
Recently, scientists have
developed systems to transmit
warnings immediately after an earthquake that will give
distant cities time to shut down critical facilities.
A few months before the Indian Ocean earthquake in 2004,
some seismologists warned that a large earthquake could
strike the coast of Sumatra. There was no way to convert this
information into practical measures at the time.
Collapsing buildings cause most deaths during an
earthquake. Engineers can design homes and offices to
withstand earthquake shaking.
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Japan is one of the most seismically active countries on the
planet and geologists know there will be a major earthquake
near Tokyo in the future - possibly soon.
Volcanic plumes deplete ozone in the upper atmosphere.
Eruptions can go undetected when clouds shroud
volcanoes. NERC scientists have developed a sensor to
monitor volcanoes, even through dense cloud.
Super-eruptions, large enough to cause a global disaster,
occur on average every 100,000 years. The last supereruption was 74,000 years ago in Toba, Indonesia.
Hurricane Katrina was the worst natural disaster in US history
with damages expected to top $100 billion.
Natural disasters waiting to ha
In 2005, the Natural Hazard Working Group in the UK identified a number
could either physically affect the entire planet or have a knock-on effect
Doug Webb/Alamy
Natural hazard
Place
Earthquake
Tokyo, Japan
Earthquake and tsunami
South east Asia
Magnitude 9 earthquake
Pacific coast, United States
Volcano and tsunami
Cumbre Vieja volcano, Canary Islands
Catastrophic failure of the Sarez
Tajikistan
Major volcanic eruption
1,500 volcanoes worldwide
Asteroid impact
Anywhere
◗ Rising sea levels
Global sea level rose on average by 1-2cm a decade during the
20th century. Sea level is predicted to rise by 10-90cm this
century.
Bangladesh, the Netherlands and cities such as New Orleans,
are near or below sea level and require dams to keep the sea at
bay.
More than 300 million people live within
one metre of average sea level and one
third of the world's population live near the
coast.
The main cause of sea level rise is thermal expansion of the
oceans: as water heats up its volume increases. Another cause
is melting glaciers and ice sheets.
Many heavily populated areas, for example,
If Greenland’s ice sheet melted completely, sea level would rise
by seven metres, although this would take many centuries.
Worst natural
disasters
since 1970
The system used to measure the size of an
earthquake is known as the Richter Scale. It is a
logarithmic scale which means that an earthquake
of magnitude nine (M9) is ten times greater than an
earthquake of magnitude eight.
appen
NASA
r of major environmental hazards that
on the global economy.
Hurricane Katrina. A record-breaking 27 tropical
storms formed in the Caribbean in 2005.
Impact
Over £1.8 trillion
Millions of people affected
Huge cost to the insurance industry
Major tsunami threat to the Atlantic,
according to some scientists
This dam threatens millions of people
lake natural dam
One in ten people worldwide live close
to a potentially dangerous volcano
A direct impact could destroy a city
Much of Bangladesh is on the flood plains of thr
◗ Tsunamis
◗ Landslides
Tsunamis are usually caused by undersea earthquakes,
volcanic eruptions or landslides.
Landslides kill and injure many people throughout the world
every year.
Eighty percent of all recorded tsunamis occur in the Pacific
Ocean – the most seismically active region of the planet.
The processes that cause landslides are well understood,
including erosion, saturated soil and deforestation.
Tsunamis in the Atlantic are rare but not impossible. An
earthquake off the coast of Portugal in 1755 caused a 12 metre
high tsunami that destroyed the city and left over 60,000 dead.
More storms with heavy rainfall, as predicted by climate
change models, will make some types of landslide more
common in the UK.
Some scientists believe that a volcano on La Palma in the
Canaries could collapse causing an enormous landslide into the
sea. This might create a tsunami 50 metres high that would
sweep around the Atlantic devastating the Canary Islands, the
west coast of Africa and the eastern coast of the United States.
Other scientists believe that a major tsunami is unlikely as the
landslide would slip gradually into the sea.
NERC’s British Geological Survey (BGS) has recorded more
landslides across the UK in recent years.
BGS has used its understanding of landslides and geological
data to make maps of likely landslide hazards.
These maps help land managers to keep land stable and
protect life and property.
A tsunami early warning system has been operating in the
Pacific since 1965.
An Indian Ocean early warning system will
begin operations in 2006 followed by an Atlantic
Ocean system in 2007.
Landslides destroy infrastructure.
The Indian Ocean tsunami,
Boxing Day 2004.
◗ Floods
In the last few decades flooding has killed more
people than any other natural hazard.
Between 1975 and 2001 the annual number of
flash floods across Europe increased.
Five million people in England and Wales are at risk from
flooding every year.
UK assets worth £132.2 billion are at risk from coastal floods.
Climate change scientists say that while summer rainfall in
Britain will reduce, the storms that come will be more severe,
causing more flooding.
◗ Storm surges
When hurricane Katrina hit New Orleans in August 2005 the
accompanying storm surge broke through the sea defences and
swamped the city, causing more damage than the strong winds.
Britain’s worst recent storm surge occurred in 1953. It
devastated much of the east coast of England and killed 304
people in the UK.
Better land management reduces flood risk.
The Flood Estimation Handbook, produced by scientists at
NERC’s Centre for Ecology & Hydrology, gives guidance on
rainfall and flood frequency, which are predicted to become
more common in the UK.
ree major rivers.
Maps produced by NERC’s British
Geological Survey show the extent
of floodplains and coastal areas at
risk of flooding, aiding flood
prediction and management.
NERC’s Flood Risk from Extreme
Events programme is addressing
environmental problems associated
with flood risk including those
caused by climate change.
Since the storm the Thames Barrier was built, along with 36
additional tidal barriers and 200 miles of flood walls.
Use of the Thames Barrier has increased from once every two
years in the 1980s to an average of six times a year over the
past five years. The decision to raise or lower the Thames
Barrier is based on data from NERC’s Proudman Oceanographic
Laboratory. The cost of getting this wrong and London flooding
would run in to billions of pounds.
Storm surges were responsible for the deaths of 300,000 people
in Bangladesh in 1970 and a further 200,000 in the 1980s.
Climate change could result in more hurricanes, increasing the
frequency of large storm surges.
Scientists can normally accurately predict storm surges several
days before they happen.
When a tropical storm’s wind speed
exceeds 118 kilometres an hour it
becomes known as a typhoon in the
northwest Pacific, a cyclone in the
Indian Ocean and around Australia,
or a hurricane in the Atlantic.
◗ Tropical storms
Of all natural hazards tropical storms are probably the
easiest to monitor and predict. Warnings are given
sometimes days in advance and forecasters can
accurately determine their strength and direction, yet they
can still cause havoc.
The UK does not have a tropical climate so hurricanes in
the strict sense do not hit our shores, but hurricane-force
winds do sometimes strike.
◗ Near Earth Objects
Many scientists believe that a huge crater beneath the Yucatan
peninsula in the Gulf of Mexico is proof that an asteroid collided
with Earth 65 million years ago, wiping out the dinosaurs and
much other life on this planet.
Scientists take the threat of another devastating impact very
seriously. An asteroid one kilometre in diameter could kill one
billion people. The last asteroid of this size collided with Earth
900,000 years ago.
Asteroids of 100-250 metres across are more frequent and a
direct impact could destroy a city. A 100-metre rock strikes on
average every 50 years, a 250-metre rock every 3,000 years.
Scientists can precisely predict the time and location of potential
impacts and there is a realistic chance that disaster could be
averted by deflecting the rock away from a collision course.
The Near Earth Objects Information Centre in Leicester, UK, is
monitoring asteroids and comets large enough to cause
substantial damage to planet Earth.
◗ Space weather
Solar flares cause power blackouts and can disrupt
communication systems and navigational aids.
The insurance, telecommunications and aerospace industries
need better space-weather forecasts to protect expensive
spacecraft.
NERC’s British Geological Survey is helping to monitor solar
activity and advising power companies on mitigation strategies.
NERC’s British Antarctic Survey has set up instruments across
Antarctica to improve space-weather prediction.
Climate models predict more ferocious storms in a warmer
world. Recent research suggests that wind speeds
increase by three percent when sea-surface temperatures
rise by half a degree centigrade. Global average
temperatures have risen by around 0.7°C since 1860.
◗ Drought
Cracked earth and dry riverbeds signal the onset of
drought. In developing countries crop failures and untold
human suffering usually follow.
Worldwide, the ten hottest years on record have all
occurred since 1990. Computer models predict that some
regions of Africa will become even drier in the future.
Improved seasonal weather forecasting can prepare
communities for drought, helping to mitigate its effects.
NERC scientists are investigating how regional weather
conditions are connected. For example, we know
unseasonal European weather, and El Niño in the Pacific,
can weaken Indian monsoons. And high surface
temperatures in the Atlantic Ocean may have caused the
2005 Amazonian drought.
The West African monsoon is under close scrutiny from
NERC scientists and African and European colleagues.
In the UK the economic implications of prolonged dry
periods are huge. Some types of clay shrink dramatically
when they dry out causing serious subsidence. In the last
30 years insurance claims for subsidence as a result of
shrinking clay soils have cost the UK economy over
£8.2 billion.
British Geological Survey scientists have made maps
showing areas of shrinkable clay hazard in Great Britain.
House builders can use these maps to built houses with
subsidence-resistant foundations in affected areas.
◗ What are we doing?
NERC scientists were actively involved in scientific
investigations following the devastating earthquake off the
coast of Sumatra, Boxing Day 2004. This work included:
mapping the sea floor, advice on rebuilding towns and
reducing freshwater contamination, helping create an early
warning system and assessing future tsunami hazards.
NERC manages Britain’s Earth observation budget and funds
satellite technology to increase knowledge of natural hazards.
NERC’s British Geological Survey monitors earthquakes and
volcanoes worldwide reducing uncertainties and improving
predictions.
NERC’s British Antarctic Survey scientists are training
instruments on the skies above Antarctica to monitor violent
solar flares that can destroy satellites.
NERC’s Proudman Oceanographic Laboratory (POL) hosts the
Permanent Service for Mean Sea Level – the global data bank
for information on sea level change. The decision to raise and
lower the Thames Barrier is based on POL data.
NERC’s Centre for Ecology & Hydrology is working on flood and
drought forecasts and their ecological impacts.
In 2005, the UK government created the Natural Hazard
Working Group. A number of NERC scientists sat on this group.
In their report, published in June 2005, they highlighted the
need for an international panel to advise governments on
potential natural hazards and recommended governments build
a coordinated warning system for the major natural hazards.
For information on natural hazard monitoring systems visit
www.nerc.ac.uk
Designed and produced by NERC Communications, Swindon. Printed by TL Visuals Ltd, Bristol. March 06.
◗ Contacts
For more information about NERC research on natural
hazards contact:
Centre for Ecology & Hydrology
Tel: 01487 772400 www.ceh.ac.uk
Natural Environment Research Council
Tel: 01793 411500 www.nerc.ac.uk
NERC Centre for the Observation and Modelling of
Earthquakes and Tectonics (COMET)
Tel: 01865 272000 http://comet.nerc.ac.uk
British Antarctic Survey
Tel: 01223 221400 www.antarctica.ac.uk
National Oceanography Centre, Southampton
Tel: 023 8059 6666 www.noc.soton.ac.uk
British Geological Survey
Tel: 0115 9363100 www.bgs.ac.uk
Proudman Oceanographic Laboratory
Tel: 0151 795 4800 www.pol.ac.uk
This briefing note draws on NERC-funded work and reports such as: The Role of Science in Physical Natural
Hazard Assessment (the Natural Hazard Working Group, 2005), Sparks, S. & Self. S. et al., 2005:
Super-eruptions: global effects and future threats: (The Geological Society of London), Hazard and Risk Science
Review 2005 (Benfield Hazard Research Centre).