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.
Q Volcanoes Q Earthquakes
One in ten of the world’s population live close to active or Earthquakes can occur anywhere but major earthquakes
potentially active volcanoes. tend to happen along fault lines in the Earth’s crust.
On average 50-60 volcanoes are active each year. Around 1,500 Although there are thousands of earthquakes each year only
volcanoes have been active in the last 10,000 years. a few damage towns or cities.
Volcanoes rarely erupt without warning, but scientists monitor The British Geological Survey
only a few of the world’s volcanoes. 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. There is still no reliable way to
predict earthquakes despite 40
The main hazards associated with volcanoes are: lava flows, years of research, but statistics
pyroclastic flows (fast moving hot rocks and debris), explosions and geological knowledge can
and mudflows. Secondary hazards include tsunamis and indicate where large
changes to regional and global climates causing temperature earthquakes are likely and what
drops, famine and disease. their effects will be.
Fine volcanic ash can stop a jet engine. Many major earthquake zones
such as California and Japan An earthquake reduced the town
In 1988 scientists suggested there would be an increase in are extremely well monitored. of Bam in Iran to rubble in 2003.
volcanic activity on the Caribbean island of Montserrat Recently, scientists have
sometime in the mid-1990s. The volcano erupted in 1995 but developed systems to transmit
good monitoring procedures meant fatalities were few, though warnings immediately after an earthquake that will give
damage to the surrounding area was extensive. distant cities time to shut down critical facilities.
Volcanic eruptions have far reaching effects on regional and A few months before the Indian Ocean earthquake in 2004,
global climate. All eruptions throw huge clouds of sulphur some seismologists warned that a large earthquake could
dioxide gas into the atmosphere. When Pinatubo in the strike the coast of Sumatra. There was no way to convert this W
Philippines erupted in 1991 a plume of gas spiraled into the information into practical measures at the time. d
atmosphere and enveloped the planet, lowering temperatures
by about 0.25 degrees centigrade for a few weeks. Collapsing buildings cause most deaths during an s
earthquake. Engineers can design homes and offices to
Volcanic activity is not entirely random. It is often seasonal, withstand earthquake shaking.
suggesting that environmental factors such as weather, climate
and sea level influence volcanoes. The volcano on Montserrat Japan is one of the most seismically active countries on the
seems to have a tendency for large eruptions in summer, maybe planet and geologists know there will be a major earthquake
because of increased rainfall. 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.
Natural disasters waiting to ha
In 2005, the Natural Hazard Working Group in the UK identified a number
Super-eruptions, large enough to cause a global disaster,
could either physically affect the entire planet or have a knock-on effect
occur on average every 100,000 years. The last super-
eruption was 74,000 years ago in Toba, Indonesia. Natural hazard Place
Earthquake Tokyo, Japan
Hurricane Katrina was the worst natural disaster in US history
with damages expected to top $100 billion. 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
Doug Webb/Alamy
Asteroid impact Anywhere
Q Rising sea levels
Global sea level rose on average by 1-2cm a decade during the Bangladesh, the Netherlands and cities such as New Orleans,
20th century. Sea level is predicted to rise by 10-90cm this are near or below sea level and require dams to keep the sea at
century. bay.
More than 300 million people live within The main cause of sea level rise is thermal expansion of the
one metre of average sea level and one oceans: as water heats up its volume increases. Another cause
third of the world's population live near the is melting glaciers and ice sheets.
coast.
If Greenland’s ice sheet melted completely, sea level would rise
Many heavily populated areas, for example, 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
Hurricane Katrina. A record-breaking 27 tropical
r of major environmental hazards that storms formed in the Caribbean in 2005.
NASA
on the global economy.
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
Q Tsunamis Q Landslides
Tsunamis are usually caused by undersea earthquakes, Landslides kill and injure many people throughout the world
volcanic eruptions or landslides. every year.
Eighty percent of all recorded tsunamis occur in the Pacific The processes that cause landslides are well understood,
Ocean – the most seismically active region of the planet. including erosion, saturated soil and deforestation.
Tsunamis in the Atlantic are rare but not impossible. An More storms with heavy rainfall, as predicted by climate
earthquake off the coast of Portugal in 1755 caused a 12 metre change models, will make some types of landslide more
high tsunami that destroyed the city and left over 60,000 dead. common in the UK.
Some scientists believe that a volcano on La Palma in the NERC’s British Geological Survey (BGS) has recorded more
Canaries could collapse causing an enormous landslide into the landslides across the UK in recent years.
sea. This might create a tsunami 50 metres high that would
sweep around the Atlantic devastating the Canary Islands, the BGS has used its understanding of landslides and geological
west coast of Africa and the eastern coast of the United States. data to make maps of likely landslide hazards.
Other scientists believe that a major tsunami is unlikely as the
landslide would slip gradually into the sea. These maps help land managers to keep land stable and
protect life and property.
A tsunami early warning system has been operating in the
Landslides destroy infrastructure.
Pacific since 1965.
An Indian Ocean early warning system will The Indian Ocean tsunami,
begin operations in 2006 followed by an Atlantic Boxing Day 2004.
Ocean system in 2007.
Q 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.
Q Storm surges
When hurricane Katrina hit New Orleans in August 2005 the
UK assets worth £132.2 billion are at risk from coastal floods. accompanying storm surge broke through the sea defences and
swamped the city, causing more damage than the strong winds.
Climate change scientists say that while summer rainfall in
Britain will reduce, the storms that come will be more severe, Britain’s worst recent storm surge occurred in 1953. It
causing more flooding. devastated much of the east coast of England and killed 304
people in the UK.
Better land management reduces flood risk.
Since the storm the Thames Barrier was built, along with 36
The Flood Estimation Handbook, produced by scientists at additional tidal barriers and 200 miles of flood walls.
NERC’s Centre for Ecology & Hydrology, gives guidance on
rainfall and flood frequency, which are predicted to become Use of the Thames Barrier has increased from once every two
more common in the UK. 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
Maps produced by NERC’s British Barrier is based on data from NERC’s Proudman Oceanographic
Geological Survey show the extent Laboratory. The cost of getting this wrong and London flooding
of floodplains and coastal areas at would run in to billions of pounds.
risk of flooding, aiding flood
prediction and management. Storm surges were responsible for the deaths of 300,000 people
in Bangladesh in 1970 and a further 200,000 in the 1980s.
NERC’s Flood Risk from Extreme
Events programme is addressing Climate change could result in more hurricanes, increasing the
environmental problems associated frequency of large storm surges.
with flood risk including those
caused by climate change. Scientists can normally accurately predict storm surges several
days before they happen.
ree major rivers.
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.
Q 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.
Q Near Earth Objects Climate models predict more ferocious storms in a warmer
world. Recent research suggests that wind speeds
Many scientists believe that a huge crater beneath the Yucatan increase by three percent when sea-surface temperatures
peninsula in the Gulf of Mexico is proof that an asteroid collided rise by half a degree centigrade. Global average
with Earth 65 million years ago, wiping out the dinosaurs and temperatures have risen by around 0.7°C since 1860.
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
Q Drought
900,000 years ago. Cracked earth and dry riverbeds signal the onset of
drought. In developing countries crop failures and untold
Asteroids of 100-250 metres across are more frequent and a human suffering usually follow.
direct impact could destroy a city. A 100-metre rock strikes on
average every 50 years, a 250-metre rock every 3,000 years. Worldwide, the ten hottest years on record have all
occurred since 1990. Computer models predict that some
Scientists can precisely predict the time and location of potential regions of Africa will become even drier in the future.
impacts and there is a realistic chance that disaster could be
averted by deflecting the rock away from a collision course. Improved seasonal weather forecasting can prepare
communities for drought, helping to mitigate its effects.
The Near Earth Objects Information Centre in Leicester, UK, is NERC scientists are investigating how regional weather
monitoring asteroids and comets large enough to cause conditions are connected. For example, we know
substantial damage to planet Earth. 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.
Q Space weather The West African monsoon is under close scrutiny from
Solar flares cause power blackouts and can disrupt NERC scientists and African and European colleagues.
communication systems and navigational aids.
In the UK the economic implications of prolonged dry
The insurance, telecommunications and aerospace industries periods are huge. Some types of clay shrink dramatically
need better space-weather forecasts to protect expensive when they dry out causing serious subsidence. In the last
spacecraft. 30 years insurance claims for subsidence as a result of
shrinking clay soils have cost the UK economy over
NERC’s British Geological Survey is helping to monitor solar £8.2 billion.
activity and advising power companies on mitigation strategies.
British Geological Survey scientists have made maps
NERC’s British Antarctic Survey has set up instruments across showing areas of shrinkable clay hazard in Great Britain.
Antarctica to improve space-weather prediction. House builders can use these maps to built houses with
subsidence-resistant foundations in affected areas.
Q 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.
Q Contacts Centre for Ecology & Hydrology
For more information about NERC research on natural Tel: 01487 772400 www.ceh.ac.uk
hazards contact:
NERC Centre for the Observation and Modelling of
Natural Environment Research Council Earthquakes and Tectonics (COMET)
Tel: 01793 411500 www.nerc.ac.uk Tel: 01865 272000 http://comet.nerc.ac.uk
British Antarctic Survey National Oceanography Centre, Southampton
Tel: 01223 221400 www.antarctica.ac.uk Tel: 023 8059 6666 www.noc.soton.ac.uk
British Geological Survey Proudman Oceanographic Laboratory
Tel: 0115 9363100 www.bgs.ac.uk 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).