Hazards Flashcards
(17 cards)
1995 Monseratt volcanic eruption facts
- the carrilleon - 12 miles Long, 3km wide
Located:
- Boundary between carribean and North American Plate - destuctive plate margin (more damaging)
- section of the island known as soufrère hill
affected, with 50% Population evacuated to the North
complex stratovolcano (also known as a composite volcano)
Andesitic and some rhyolitic lava = high viscosity = greater hazard
Benioff zone
Speed of onset = rapid
Associated with island arc’s often have partial wet melts = this allows water-bearing sediments to be subducted into mantle and as temperatures rise water is released and the amount of volatiles are increased so increasing the scale of the hazard event
Stats:
- VEI = 4
- 23 died In 1997
- 2/3 island covered in ash
- Port + Aport closed + farmland destroyed +
- Forest fires started due to pyroclastic flows
- £41 million given in aid by British government
Prediction:
- The Montserrat Volcano Observatory (MVO) was established in 1996, providing monitoring and early warnings for next eruption (also a long term response)
- Scientists used seismometers, gas sensors, and satellite imaging to track changes.
Preparedness
- Initially limited, but improved over time.
- Emergency plans and evacuation routes were developed as risk increased.
- By mid-1997, evacuation drills and hazard maps were in place.
- However, the initial response was slow, and some residents were caught off-guard by the major eruption in June 1997
Primary impacts:
lava flows, tephra, volcanic gases, pyroclastic flows
Secondary impacts:
Lahars
Short-Term Responses:
- Evacuation of over 7,000 people, mainly from the south
- British Navy and aid agencies helped transport evacuees and deliver emergency supplies.
- Temporary shelters/housing set up in the north of the island and buildings reinforced
- Exclusion zone established around the volcano to prevent access to dangerous areas.
- Ash and debris cleared where possible.
Long-Term Responses:
- UK government provided over £420 million in aid over several years.
- New infrastructure built in the north, including a new capital (Little Bay) and airport.
- Incentives and support for people to relocate, both within Montserrat and to the UK.
- Long-term rebuilding of economy, focusing on tourism and geothermal energy.
Recovery:
5-10 years
Criticisms:
- Early response seen as slow by locals.
- Many people were left in temporary shelters for years.
- Economic decline and mass emigration (population fell by over 60%).
2010 Haiti earthquake
Tuesday 12th January 2010
Located:
15 miles southwest of Haitian capital Port -au- Prince.
Stats:
- VIII - IX mercalli intensity scale
Magnitude 7.0 - followed by two aftershocks
magnitude 5.9 and 5.5
220,000 killed, 300,000 injured, 1.5m became homeless
North American plate sliding past Caribbean Plate - conservative plate margin
Focus on 5miles (depth)
the shallow-focus earthquake created more intense, localised shaking.
Transport + communication damaged, Poor Sanitation + health, looting occured
80 % of population live on $2 or less per day
46 people per square kilometer
Secondary hazards:
- Landslides
- Fires
- Cholera outbreak
Prediction: CANNOT PREDICT EQ’s
No prediction systems in place before the earthquake.
Preparation:
Infrastructure was weak.
70% of the population lived in informal housing with no earthquake-resistant design.
The capital, Port-au-Prince, had poor building codes, with buildings constructed from substandard materials.
Haiti had no national emergency response plan or efficient disaster management system in place.
Lack of public education on disaster risk meant many were unaware of how to react during an earthquake.
Mitigation:
20% buildings were earthquake resistant
Short-Term Responses:
International aid provided food, water, and medical care.
US sent 3,500 troops to help.
Temporary shelters set up for over 800,000 people.
Emergency hospitals and rescue teams deployed.
Long-Term Responses:
$100 million pledged by the World Bank; debt relief given.
Reconstruction of hospitals, schools, and housing.
IGO’s attempt to improve building standards/building codes and disaster management plans.
NGOs ran clean water, health, and employment schemes.
Education programmes = “Build back better”
Recovery time:
5-10 years
Criticisms:
Poor coordination and slow aid delivery.
Over-reliance on foreign aid.
Many still in camps years later.
Challenges such as poverty (80% of the population) and political instability slowed progress.
Ongoing efforts to create more earthquake-resistant infrastructure, but much remains to be done.
CORRUPT GOVERNMENT
11th of March 2011 Japan Earthquake and tsunami
Location:
- Tohoku - 100km off the coast of Japan
- Japan is located on the Pacific Ring of Fire (75% earthquakes occur here)
Occurred along the Benioff zone
Stats:
- IX - XI on mercalli intensity scale
- Magnitude 9.0 - 5th strongest globally
- Focus 25km /15 miles
- 18,000-20,000 killed, 6000 Injured, 300,000 homeless
- Convergent/destructive plate boundary - oceanic pacific
Plate is subducted beneath Eurasian plate
Despite having a deeper focus, the subduction zone dynamics caused a more widespread release of energy
338 people per square kilometer
Secondary hazards:
- Liquefaction
- Tsunami
- Landslides
- Flooding
Prediction: CANNOT PREDICT EQ’s
- A highly advanced seismic monitoring system
- Over 1,000 seismometers and early warning systems
- Alerts were sent to phones and TV stations seconds before the shaking began
Preparedness:
- Strict building codes meant many structures withstood the quake.
- Regular earthquake drills and public education campaigns.
- Tsunami warning systems were in place, but failed to anticipate the 10–40m waves.
- Evacuation shelters existed, but many were overwhelmed or destroyed.
Response:
- Good Education/training for earthquakes
- Good initial preparedness but slow/uncoordinated response from government
Short-Term Responses:
Automatic shutdown of 11 nuclear plants occurred, but Fukushima was overwhelmed by the tsunami, leading to a radiation crisis.
100,000 soldiers sent for rescue.
70,000 emergency shelters/temporary homes costing = £144 bn
120 countries provided aid
Nuclear evacuation zones set up.
Quick clearance of roads and airports = 25 million tonnes of debris moved
Long-Term Responses:
$235bn in economic losses = $300 billion reconstruction plan.
Improved sea walls/tsunami barriers and warning systems.
Stricter building codes and regular drills for nuclear plants
Mental health and community support.
Recovery:
5-10 years
Criticisms:
Delays at Fukushima nuclear plant.
Communities disrupted by relocation.
2011 Japan Tsunami – Summary
Date & Cause: 11 March 2011, caused by a magnitude 9.0 earthquake at a destructive plate boundary.
Tsunami: Waves up to 40m high, reached the coast in 30 minutes.
Reached 10km inland
Fukushima nuclear meltdown, radiation released.
Effects:
300,000+ displaced, radiation contamination.
Evaluation:
Fast and organised response due to Japan’s development.
Failures included underestimating tsunami size and nuclear risk.
2010 Eyjafjallajokull (E15) Iceland volcanic eruption
Location:
Constructive plate boundary between North American and Eurasian plate (less damaging)
Stats:
- VEI = 4
Glacier above the volcano caused flooding over 100x capacity
Horticulture cost £3million a day and Europe lost $2.6 billion GDP
Ash made fertile Soil
Speed of onset = not rapid
stratovolcano (also known as a composite volcano)
basaltic lava = lower viscosity = lower hazard
Prediction:
The volcano was closely monitored by the Icelandic Meteorological Office using:
- Seismometers (to detect earthquakes)
- GPS and ground deformation sensors
- Gas detectors and satellite imagery
Preparedness:
Emergency response plans were in place, including evacuation procedures.
Local residents near the volcano were evacuated quickly (approx. 800 people).
The air traffic authorities were prepared to monitor and respond to ash cloud risks.
Primary impacts:
lava flows, pyroclastic flows, ash falls, gas eruptions, tephra
Secondary impacts:
jökulhlaups
Short-Term Responses:
Over 100,000 flights cancelled to avoid ash cloud damage to aircraft.
Airspace closed across much of Europe for 6 days.
700 Local residents evacuated due to ashfall and flooding from glacial melt.
Emergency services provided masks and shelter for locals.
Long-Term Responses:
Volcanic ash monitoring improved with satellite and radar systems.
Ash contaminated water and caused respiratory illness
Development of international aviation protocols for ash clouds.
Tourism promoted after eruption to support local economy = Year after eruption tourist centre was built in Iceland
Recovery:
1-2 years
Criticisms:
Some argued the airspace closure was too cautious.
High economic cost – airlines lost around $1.7 billion.
Asian Tsunami
Affected 18 countries in south-east Asia and Africa
Lead to over 225,000 deaths in 12 countries
Bulk in Indonesia 170,000 deaths + Sri Lanka over 35,000 deaths
Economic damage of US$10 billion
Most of Sri Lanka’s fishing boats were destroyed
Tourism was impacted as people were reluctant to visit the areas
17 million people were displaced
90,000 buildings were destroyed in Sri Lanka
Severe damage to mangroves and coral reefs
Disaster modification
Event: Before the event occurs
- Earthquake resistant buildings
- Hazard risk mapping using GIS, land use zoning, draining crater lakes, barriers and channels to divert lava flows
- Tsunami = land use zoning, offshore barriers, sea walls, replant mangrove forests
Vulnerability, increasing resilience: Before event occurs
land use zoning
Hazard resistant buildings
Hazard risk mapping
Evacuation routes
Earthquake drills
Storage of food, water and medical supplies
Monitoring and warning systems
Loss: After the event occurs
Evacuation
Search and rescue teams
Emergency aid = food, water, medical
Short-term aid = shelter, water/electricity supplies
Development aid = help with reconstruction
Insurance = to help people rebuild
Local communities = support each other
Aid may be provided by:
Non-governmental Organisations (NGOs) such as the Red Cross, Medicin San Frontiers and Disasters Emergency Committee
Intergovernmental Organisations (IGOs) such as the UN and World Bank
National and local government
Hazard management cycle/disaster risk poverty index/parks hazard response model/disaster modification
Hazard
Response
Recovery
Mitigation
Preparedness
How quality of life changes over time after a hazard event
How poverty increases vulnerability to natural disasters
The procedures put in place in order to protect from disasters = hazard resistant buildings etc
Prediction and forecasting
Prediction is knowing when (temporal scale) and where (spatial scale) a hazard will occur
Forecasting gives a percentage chance of a hazard occurring over a set period of time
Cannot predict earthquakes
There are signs of warning before an eruption of volcanoes
For earthquake induced tsunamis you cannot predict the earthquake itself
Ocean monitoring technology can be used to detect tsunami = warnings issued to coastal areas which may be affected
In the 2011 Japanese tsunami the height of the tsunami was underestimated so the warnings were not accurate
Volcano types
Types of Volcanoes:
Shield Volcano
Wide, gently sloping shape
Frequent, non-explosive eruptions
Runny basaltic lava (low silica)
Found at constructive boundaries and hotspots
Example: Mauna Loa, Hawaii
Composite Volcano (also called Stratovolcano)
Tall, steep-sided with layers of lava and ash
Explosive, dangerous eruptions
Andesitic or rhyolitic lava (thicker, more viscous)
Found at destructive (convergent) plate boundaries
Examples: Mount Fuji (Japan), Mount St. Helens (USA) Monseratt
Hazard profiles/Modified Mercalli Intensity Scale/Moment Magnitude Scale (MMS)/Volcanic explosively index (VEI)
The Modified Mercalli Intensity Scale is used to measure the intensity - The scale goes from I to XII
The MMS goes from 1 which are not felt by humans to 10
The MMS is a logarithmic scale which means that a 6 on the scale is a ten times increase in amplitude from a 5
The energy release is 32 times greater
The Volcanic Explosivity Index (VEI) is used to measure the size of an eruption
This can not be measured on a scientific instrument so is calculated based on a series of measurements and observations
These include:
Height of material ejected into the atmosphere
Volume of material
Duration of the eruption
This is a logarithmic scale from 0-8
Hazard profiles can be used to compare tectonic hazard events
Hazard profiles usually include information about:
Magnitude
Speed of onset
Areal extent
Duration
Frequency
Spatial predictability
The Degg model
Suggests a disaster occurs where a natural hazard event meets a vulnerable population
Resilience vs vulnerability
Affects communities
Pressure and release model
Pressure = vulnerabilities
Release = need to reduce the hazard or the vulnerability
Hazard risk equation
Risk = Hazard x venerability/capacity to cope
What factors influence vulnerability?
Governance
Geological factors = population density, isolation and accessibility, degree of urbanisation
Hazard profiles
(magnitude, speed of onset and areal extent, duration,
frequency, spatial predictability) are important in understanding hazard impacts.
Theory of tectonics
1912 = Wegeners theory of continental drift
1940 = Sonar and Radar used to reveal the shape of the ocean floors (Harry Hess)
1960s = Crust samples gathered and radiometric dating carried out
1963 = Theory of sea floor spreading proposed by Wilson
1965 = Wilson and Hess propose the theory of plate tectonics combining sea floor spreading with continental drift
Scientists agree that the plates move, but there is still debate over the mechanisms that cause the movement
