Tectonic processes and Hazards Flashcards
What was the name of the man who first Proposed the Tectonic Plate theory?
Alfred Weneger
What was the name given to Weneger’s theory?
Continental Drift Theory
What did Weneger base his theory upon?
Fossils from similar species were found oceans apart, (fossils from east SA were found on west Africa and these continents fit together)
Similar geology on different continents
Shapes of continents fit together
Why did people not accept Weneger’s theory at first?
Because he couldn’t explain why the continents had moved
What did the invention of Sonar reveal?
That there were geological features on the sea floor, people began to measure sea depth
What property of the mantle was discovered in 1919 using seismic waves and how did this help Weneger to prove his theory?
The mantle is Semi-Plastic, this meant that Convection currents existed in the mantle.
A convection current helped Weneger put a reason behind his theory.
What did scientists map in 1954 where they discovered a worldwide pattern?
Volcanic eruptions and earthquake epicentres.
What was the name of Hess & Dietz’s developed theory?
Sea Floor Spreading
What are the principles of sea floor spreading?
Magma rises from the mantle through a fault, this then cools underwater forming new crust. This new crust is made at the boundary ridge and forces existing crust outwards.
What is Palaeomagnetism?
Palaeomagnetism is where magnetic directions of older rock were found to face different directions than that of newer rock. Showing the sea floor was moving.
How was palaeomagnetism significant to Hess & Dietz?
It helped them to give evidence for their theory of sea floor spreading, helping it to be accepted by scientists.
Why was the first commercial GPS significant in proving plate theory?
Allowed people to track movement of the crust themselves
people could conduct independent research
Explained the tectonic theory.
What boundaries do volcanos form on?
Divergent and Convergent (Subduction)
How is the Volcanic Explosivity Index (VEI) calculated
Volume of Ejecta Height of eruption Qualitative descriptions Past activity Height of Ash Cloud
What are the 3 main typed of lava
Andesitic, Basaltic and Rhyolitic
Why are Andesitic and Rhyolitic lava more explosive than Basaltic lava
Because they have a high viscosity and high gas content
At what volcano type would you find Basaltic Lava
Shield
What are Pyroclastic Flows?
A mixture of hot rock, lava, ash and gas that is ejected from the volcano.
Travels at +60mph and is often fatal
What is the cast study for pyroclastic flows?
Montserrat , Caribbean, 1995
At what boundaries do Earthquakes occur
Conservative, Convergent (both destructive and constructive)
What is the Benioff Zone?
The line of smaller seismic hazards along the subducted plate
What is an intra-plate earthquake?
an earthquake that occurs not at a plate boundary
Caused by stresses at an ancient fault line that can sometimes crack.
Define a Natural Hazard
A naturally occuring process or event that has the potential to affect people
Define a natural disaster
A major natural hazard that causes significant social, environmental or economic damage
Define vulnerability
The ability to anticipate, cope with and recover from a natural hazard
How are Island arcs formed
When 2 oceanic plates meet and 1 is subducted
magma rises from the trench and cools forming underwater volcanos, these volcanos can eventually get so big they reach the waters surface forming and island arc
What is the name given to the area surrounding NA, Asia and NZ that has very high tectonic activity
The Pacific Ring of Fire
What are P waves
P waves are the fastest waves
they are a longitudinal wave
The travel through both solids and liquids
Not very damaging
What are S waves
Slower waves
Only travel through solids
transverse waves
Much more damaging
What are Love Waves
They are the slowest waves
Only found at larger earthquakes and near epicentre
The most destructive wave type
Give 2 examples of primary effects of earthquakes
Ground Shaking
Crustal Fracturing
Give 3 examples of secondary effects of earthquakes
Liquifaction
Landslides/ Avalanches
Tsunamis
What are the general socio-economic impacts of volcanic eruptions
Death
Buildings and infrastructure destroyed
Houses destroyed
Increased Unemployment
Young people leaving the area (top-heavy population pyramid)
What scale is used to measure volcanic eruptions
Volcanic Explosivity Index (VEI)
What can scientists use to predict volcanic eruptions
Small earthquakes cause by pressure inside the volcano
Changes on the surface of the volcano and it pushes outwards
Change in the tilt of the volcano as the magma moves inside
Gas leaks out of the volcano
Describe how a tsunami is formed
Earth quake or landslide underwater throws a column of water into the air
This falls back down sending a very fast wave in all directions
This wave travels until it reaches a coastline
The friction caused by the sea bed at shallower water causes ‘wave shoalling’
This is where the wave is compressed and increases in height
Then it hits the shore
Give examples of impacts of a Tsunami
Damage to buildings and infrastructure
Small islands could be completely destroyed
Death (drowning, hit by debris)
How can a Tsunami be predicted?
like an earthquake, it is difficult to predict a tsunami
Early warning systems have been set up in the Pacific Ocean which uses buoys to monitor changes in sea level
Give an example of when a Tsunami warning system was used
Japan 2011, warnings were sent out only 3 minutes after the earthquake which gave people enough time to evacuate before the tsunami hit
However, it underestimated the size of the tsunami so many people didn’t evacuate
Describe causes and impacts of a case study example of a tsunami in an LIC
Indian Ocean tsunami, December 2004
mag 9 earthquake
Many countries affected were LICs so had no warning system
230,000 died
1.7 million left homeless
Thailand, $25 million per month lost from tourism
Water supplies and soil contaminated by salt
What is the Hazard-Risk equation?
Risk = (Hazard x Vulnerability) / Capacity to cope
What is the case study for Earthquakes in contrasting countries?
Haiti vs Japan
Compare and contrast the impacts of the Haiti 2010 and Japan 2011 earthquakes
Haiti. Japan
mag 7.0 mag 9.0
300,000 dead 20,000 dead
1.3 million homeless 130,000 homeless
$14 billion costs $240 billion
Social impacts were far worse in Haiti however economic damages were worse in Japan
What is the Degg’s Model?
Shows the relationship between hazards and a vulnerability and how both are required to cause a natural disaster
Describe the PAR model
Shows a countries vulnerability to hazards
3 stages that cause vulnerability: Root causes, Dynamic pressures, unsafe conditions
one stage causes the next and combined with a hazard event they lead to disaster
Describe the PAR model for the Haiti 2010 earthquake
Root causes:
Heavily in debt
Corrupt government
80% of population lived below poverty line
Dynamic Pressures:
No disaster preparation or management systems
Rapid urbanisation with slum-like housing
Deforestation and soil degradation allowed landslides
Unsafe conditions: Liquefaction amplified seismic waves Unsafe housing Buildings were constructed quickly and cheaply Poor infrastructure meant poor response <50% of people had access to clean water
Give a case study example of an earthquake in an emerging (BRIC) country?
Sichuan, China 2008
Magnitude 7.9 earthquake
How did the impacts of the Sichuan earthquake differ to those in Haiti?
They were similar as many people were injured and there was a lot of economic loss. Also some buildings were not safely built so fell easier
However, China’s government sent 130,000 soldiers and relief workers to the area
Medical services were restored
People most at risk were relocated
Government gave $10 billion for rebuilding
Within 2 weeks many houses were being rebuilt
What steps had Japan made to prepare for the 2011 earthquake?
Buildings built to withstand earthquakes
Educated population on how to act in an earthquake
10-metre high tsunami walls
offices and homes have emergency kits
Early warning systems
What did Japan do in response to the earthquake in 2011?
110,000 troops deployed immediately
All radio and TV shows broadcast what to do
Bank of Japan offered $183 billion to support economy
Japan accepted recovery aid from over 20 countries
Assess the statement that ‘the world is becoming more hazardous’
Number of natural disasters has risen dramatically since 1960
This could be down to improved monitoring and reporting
Geophysical disasters have stayed at a fairly constant rate, meteorological hazards have increased drastically
Less people die now than in the past
average economic damages for a disaster have increased from $20 billion to $100 billion in just 20 years
Why might data on natural disasters be inaccurate?
The focus is on rescue not data collection
There are differences in data collection and classification
Some hazards occur in remote areas and aren’t as well documented
What would have a faster speed of onset, Earthquake or Volcanic eruption?
Earthquake
What would have a longer duration, earthquake or volcanic eruption
Volcanic eruption
What would have the more widespread areal extent, earthquake or volcanic eruption
Earthquake
What has the most predictable spatial predictability, earthquake or volcanic eruption
Both are predictable because they only tend to happen on plate boundries
What has a higher frequency, earthquake or volcanic eruption
Earthquake
Give the case study example for a multiple hazard zone
The Philippines
Give examples of the range of hazards that occur in the Pilippines
Volcanos and earthquakes - located on the pacific ring of fire
Tsunamis - located in the Pacific, the most tsunami-prone ocean
Hurricanes - Sits in the South East-Asian Typhoon belt. Has 15 typhoons per year
Steep topography- makes landslides common
What factors are increasing the Philippines vulnerability to hazards?
Rapid urbanisation and high population density
The poor live on the coast and are exposed to storms and tsunamis
25% of population live in poverty
What are the 4 stages of the Hazard management cycle?
Mitigation
Preparedness
Response
Recovery
Give examples of hazard mitigation
Plan zoning and Land use
Enforce building codes
Build defences e.g tsunami walls
Hazard resistant design
Give examples of hazard preparedness (hazard management cycle)
Implement early warning systems
Organise services and evacuation
Raise awareness, e.g earthquake drills
Give examples of hazard response
Search and rescue of missing people
Restore infrastructure as quickly as possible
Ensure medical care and law enforcement continue
Give examples of short term hazard recovery
Restore health, power, transport, water and financial services
Remove debris and clean up
Provide food and shelter for those effected
Give examples of long term hazard recovery
Rebuild homes, schools, infrastructure and business
Some countries ‘build back better’ where infrastructure improves when it is rebuild after as hazard
What is the name of the model which describes how countries respond to a hazard?
The Park Model
How might the shape of the park model differ between an LIC and a HIC?
In a HIC the curve would be shorter as there is quicker response and reconstruction is quicker
In a LIC the curve would be longer and may never reach a normal level again as they can’t afford to fully reconstruct
Give some examples of hazard adaption strategies
Hi-Tech monitoring - GIS, Early warning systems, Satellites to transmit data, Mobile Phones
Crisis mapping - After Haiti 2010, a map was created showing all people who are in need of food etc for volunteers to use
Modelling hazard impacts - using algorithms to predict likely impacts of hazards
Public education - regular drills, making emergency kits, etc
Who are the key players in managing loss?
Aid donors
NGO’s
Insurance companies
Local communities
What are the different ways aid can be provided for a tectonic hazard?
Cash
Personnel
Services
Equipment
How are NGO’s involved in managing loss?
When a countries government is struggling to do it themselves
Provide funds, co-ordinate search and rescue and start reconstruction
NGO’s can assist in recovery by rebuilding schools, medical centres and housing
How are insurance companies involved in managing loss?
They help to cover economic losses of businesses or individuals after a hazard
$54 billion was spent in 2011 as a result of earthquakes
How are local communities involved in managing loss?
They are often very involved in search and rescue
Especially in isolated, rural communities
