Natural Hazards

Earthquakes and Volcanoes

Primary and Secondary Effects

VOLCANO: ICELAND Case Study

• April 2010
• North American Plate and Eurasian Plate moving away from eachother- constructive
• ash cloud rose 11,000m into air
• lava flows
• melted 150m thick ice cap = major flooding
• ash filled rivers = blockaging
• 20 farms destroyed from ash = costly
• Airspace closed across Europe - 17,000 flights cancelled a day
• cost airlines $2 billion
• £102 lost in London from tourist income

VOLCANO: ECUADOR case study

• South Colombia, 400km from the West Coast -- 2006
• 10km ash cloud into sky
• huge lava flows
• up to 5cm of ash
• pyroclasric flows raced down slopes - destroyed 7 villages and 5,000 people homeless.
• 6 died
• hot ash = breathing difficulties
• lava and ash covered fertile farmlands & ruined crops and livestock
• roads impassable, local airports closed

EARTHQUAKE: JAVA, INDONESIA Case Study

• 6,000 died and 37,000 injuried
• 154,000 homes destoyed, leaving 1.5 million homeless
• aftershocks 
• business ruined and loss of income
• Hindu Temple badly damaged
• Overall damage - US$3 billion

CONSTRUCTIVE

• plates move away from eachother & magma rises
• volcanoes gently erupt all the time
• small earthquakes from friction between mantle and moving plate
• type of crust does not matter

COLLISION

• two plates hit eachother and fold mountains form. Varied sized earthquakes form
• need the Same type of crust

CONSERVATIVE

• two plates move alongside eachother & create large earthquakes
• type of crust does not matter

DESTRUCTIVE

• oceanic plate sinks underneath the less dense continental plate. Oceanic plate melts at bottom = volcano!
• sudden movement of the plate releases this pressure and causes earthquakes

Why live in Volcanic areas?

• Geothermal Energy - hot rocks below ground heats water to create steam which dives turbines. Provides 70% of energy need in New Zealand
• Tourism - volcanic landscapes with beautifuk scenery. Jobs from tourist attractions
• Fertile Soils - volcanic rocks are rich in minerals and when whethered, form fertile soils = ideal for growing crops
• Raw Materials - raw materials for many products come from volcanoes
• Mineral Extraction - valuble minerals can be extracted when volcanic activity occurs

Composite Volcanoes

• lava is acidic
• created along destructive plate margins
• lava is viscous so creates steep mountains

Shield Volcanoes

• lava is basic
• occur along constructive plate margins.

Kashmir Case Study - 2005

• Indian Plate and Eurasian Plate colliding. Mountainous area on the boarder of India

Effects

• 79,000 killed, 100,000 injured
• building collapsed 
• millions of homes destroyed
• diseases spread - contaminated water
• harsh winter = people died and only harsh tents to live
• loss of jobs
• schools and books damaged
• overal cost $5 billion

Responses

• military helicopters take injured and military hospitals opened
• food and supplies carried from other countries for free
• Red-Cross built water supplies

LA Case Study

• conservative plate boundary
• 1994

Effects

• 9 bridges collapsed
• 7 killed
• motorists trapped under rubble
• landslides moves homes down slopes
• 12,500 buildings damaged

Responses

• all schools re-opened after a week
• electricity supplies repaired within hours
• 80,000 new housing units built
• food handed out by popular stadium

Monsterrat Case Study - 1995

• North and South American plates being subducted under the Caribbean plate
• August 1995 people evacuated North of Monsterrat
• April 1996 - everyone forced to leave capital city of Plymouth
• 1997 - south of island covered in hot ash
• 2005 - south of island out of bounds. Population has increased to over 8000
• present day - volcano is still erupting. People are re-building from damage

Mount St Helens

• Western Northern America, Washington

The Eruption

• Pyroclastic Flows - 7000 animals kiled. 61 died. 
• Ash Cloud - ruined crops and farming machinery. cost was $175 billion. Made roads unstable
• Shape of Mountain - top was blocked by old solidified lava. After eruption - side had blown out and the top had collapsed
• Landslides - snow at the top melted and caused mudslides. They flowed down river alleys at 35m per second.

Long Term Effects

• US Government gave $951 million in aid to rebuilt industry in area
• area now tourist attracton - local economy wealthier than before
• increased risk of flooding due to new landscape

How might we prepare?

• Earthquake shaking maps
• Education
• Building codes -strict building regulations
• Earthquake proof builidings
• 'Appropriate Technology'
• Retrofitting - addings things to old buildings to make it earthquake resistant

Bamboo homes in Costa Rica was 'appropriate technology' 

Earthquake Proof Buildings

• roof weights to counter shock waves
• Cross bracing to give added strength
• Automatic window shutters to prevent falling glass
• Automatic sprinkler system to prevent fires
• rubber shock absorbers

How might we prepare?

• Emergency kits
• volcanic hazard maps
• restriciting access and evacuaiton
• monitoring of volcano
• improved building design

Evacuation in Java, Indonesia Case Study: EVACUATION

• evacuation on May 2006 from the volcano they called Mount Merapi
• Orange Code - Children and elderly women taken to emergency shelters
• Red Code (highest level) - village people forced to leave 

Mount Etna, Italy Case Study: REDUCING THE ERUPTION ITSELF

• bulldozers built earth and rock walls to direct lava away from villages
• planes and helicopters dropped cold water to cool and slow down the lava flow
• in the past - lava diverted away by using military bombing and dynamite 

Sloping Roofs - ash slides off instead of collapsing home

Air Filter systems - stop ash coming into homes

Plastic Roof coverings - ash wont be able to corrode the roof

Sealing doors and windows - ash particles cant get in 

They form where the sea surface temperatures are over 27oC and form between 10o and 30o North and South of the equator.

How do they form?

• several thunderstorms drift over warm seas
• the warm air from the sea surface combines with the thunderstorms and warm air begins to rise
• more warm air rises, and due to the Earth's rotations, starts to move in a spiral. It cools an condenses forming clouds, releasing much energy.
• the air starts to rise faster and cooler air is sucked downwards. Windspeed starts to increase.
• the tropical storm drifts over the ocean, picking up warm moist air. Cold air is drawn into the eye.

Forecast -- Prepare -- Act

Forecast

• can be accessed on internet. Regularly updated.
• includes an area of uncertainty, where the hurricane may strike within a 3-day or 5-day period.
• people who live within the area should prepare 
• they also show, wind speed, current centre location, day and what time, predicted path

Prepare

• education programmes for how to respond
• school lessons, posters leaflets giving advice on drawing up a family disaster plan, putting together an emergency kit and simple methods of protecting their homes
• tropical storms are closely monitored by angencies like the Nation Hurricane Centre

How can LEDC's prepare?

• training locals in how to organise others in evacuation
• educating women on what to wear incase they need to swim
• building homes on stilts and cyclone shelters

Physical

• damage to buildings
• roads and infrastucture damaged
• loss of animal habitats 
• sea fish killed

Social

• trauma and stress
• water-borne diseases
• job losses due to damage to industries
• food and water shortages

Economic 

• repair and insurance claims
• loss of income from closed business
• crops destroyed

Hurricane Hanna

• 550 died
• City of Gonaives badly damaged
• tin-roofed homes across country destroyed
• leaving 1 millions people homeless
• Much of low-lying Gonaives was flooded
• roads impassable
• - other parts of Haiti - whole villages buried under mudslides
• - little natural defence from mud slides due to forests being removed
• - crops destroyed along with cows and goats
• - people left with no food or income

What did they do?

• United Nations troops has to supervise food aid distribution
• three days later, another hurricane hit Haiti taking 74 more lives and worsening the food crisis

• many people think climate change from global warming has increased the number of storms
• other believe that it has stayed the same
• scientists say it will start to decline in the future

Why are opinions divided?

• satellite technology has only been used to monitor since the late 1960's
• before -- accounts from ships' logs, aeroplane reseach flights and simple weather recording instruments were used
• scientists beliveed that the strenght of the storms were greater than what was actually recorded at the time
• there is a natural cycle of variations in the number of hurricanes

Increases

• number of tropical storms has doubled in the last 100 years
• since 1995, they have become more frequent and more intense
• due to global warming, sea surfaces have risen by 0.5 oC in the last few decades

Stays the Same

• do not have enough evidence linking global warming to changes in the number of tropical storms
• short term changed to the number of tropical storms may not be due to the actions of people
• changes to the number of tropical storms
• the changes are part of a natural cycle

Decreases

• technology predicts that the number of tropical storms will fall after 2080

Natural Causes

• lightening
• spontaneous heating
• volcanic eruptions
• hot, dry weather
• droughts
• Santa Ana Winds 
• South facing slopes - sun dries out vegetation

Human Causes

• accidents
• broken bottles act as magnifier
• slash and burn - method used by farmers to clear land to grow crops
• arson
• sparks, chimneys, BBQ's

Combo of both!!!

California Wildfires Case Study: 2007

• destroyed over 200,000 hectares of grassland and woodland
• 640,000 people had to evacuate their homes
• 9 died, 85 injured
• over 1,800 homes destroyed
• damage cost US $1.6 billion.
• trauma from seeing loss of homes
• clouds of smoke blotted out the sun and raised levels of air polltuon to three times the normal level
• caused breathing problems
• business and factories had to close
• distrupted important trade
• farms and crops damaged and dead
• many species of animals killed in teh blaze

Colorado - 2012

• extremely dry winter before
• arsonists
• dry thunderstorms

Laguna Fire, California - 1970

• started by downed power lines
• during Santa Ana winds 

Tasmanian Fires, Australia - 1967

• had its driest 8 motnh period since 1885.
• several bushfires from extremely dry and hot weather
• some were caused by deliberate burning

Responses to wildfires

• public educated on how they start
• fire line/ fire breaks
• removing dead leaves and branches
• backfires
• public advised to have a family evacuation plan
• wildfire risk map
• people evacuated
• given advice on burning things to reduce sparks
• air drops: released from aircraft onto fire
• areas sprayed ahead of fire to stop from spreading

Smokey Bear Case Study

• Climate change has an effect on the number of wildfires
• other scientists feel that periods of increased wildfires are part of a natural cycle where there are periods of higher temps and lower rainfall.

Calfornia Wildfires due to Climate Change Case Study

• vegetation grew heavier than normal and tehn ignites during long draughts
• parts of the United States may experience several wet years followed by several drier than normal
• during these periods, wildfires can spread very quickly
• droughts or heat waves would lead to wildfires larger than ever before

Climate Change could lead to more and larger wildfires

• researchers say - the are burned by wildfires could double by teh end of teh century of the climate warms