Unit 4 tectonics

what do we mean by risk?

the probability of a hazard occuring and creating loss of lives and livelihoods

why do some people place themselves within the risk area of a hazard?

• hazards are unpredictable and people may perceive an area they live in to be safe

• lack of alternative locations to live especially if you are poorer

• an assessment that economic benefits outweigh the costs e.g. areas of rich volcanic soil for farming.

what do we mean by vulnerability?

the susceptibility of an individual or community to the impacts of hazards.

what is the risk equation?

risk= frequency of hazard x level of vulnerability divided by the capacity of a population to cope.

what makes an area more likely to be at risk of hazards?

• closeness to location of hazard

• infrastructure quality and building design

• population density is high

what makes an area less likely to be at risk from hazards?

high quality, aseismic designed buildings

lower pop density

higher predictability level

what is the pressure and release model of vulnerability?

explains how levels of vulnerability can be increased and decreased by 3 key factors:

1. causes

2. pressures

3. conditions

what can the difference in vulnerability explain?

explains why similar haards can have such difference of impacts

The pressure model shows?

the increasing in vulnerability

what does the release model show?

the reduction of vulnerability

what does a hazard profile show?

a comparison of different hazards based on their physical characteristics

what physical characteristics are included within the hazard profile?

• magnitude

• speed of onset

• aereal extent

• duration

• frequency

• predictability

example of similar hazard profiles:

what two tectonic events case studies have similar hazard profiles?

Loma Prieta 1989 and 2010 Haiti Earthquake

RESPONSES TO TECTONIC HAZARDS:

what 3 things are key to reducing vulnerability to hazards?

monitoring

predicting

warning

why is prediction key to reducing vulnerability?

• warn people and gives them enough time to evacuate

• prepare for a hazard event

• manage the impacts more effectively

• minimises loss of life

PREDICTION OF EARTHQUAKES?

• precise earthquake prediction of exact time and location is very difficult

• it is possible to identify WHERE they will strike but not when it will strike

what are some of the key ways that earthquake-prone areas are monitored?

• tilt meter and gravity meter which measures small movements around a fault

• radon gas meter- levels of radon gas dissolved in water can increase before an earthquake

why are many of these techniques limited to conservative boundaries?

in a destructive plate boundary, the fault lines are not accessible to reach

(therefore it can be said that using prediction to reduce vulnerability to the impacts is limited)

CASE STUDY OF PREDICTION: SAN ANDREAS FAULT

how do the USGS predict future earthquakes?

use the location of past events and locations to predict future earthquakes

what is the probability that San Francisco will have an earthquake of a magnitude 6.7 or greater?

the probability is about 99%

how is prediction useful as a vulnerability reduction strategy?

it means people can be evacuated before the natural disaster occurs which can drastically reduce vulnerability.

THE SOUTHERN CALIFORNIA EARTHQUAKE CENTRE (SCEC) TERRA SHAKE PROJECT:

what does the ‘Terra-shake’ project aim to predict?

how the ground will shake based on geology

damage that the earthquake will create.

how could these predictions from the project reduce vulnerability?

Governments know how to try and manage the effects of the earthquake

They can reinforce infrastructure to be extremely safe

monitoring, prediction and warning of volcanic eruptions

how can volcanic eruptions give a suggestion as to when they will erupt?

preceded by a number of environmental changes that can be monitored to suggest as to the likelihood of an eruption

what environmental changes are seen before an eruption?

• seismic activity

• ground deformation- tilt metres and laser measures can detect changes in slope angle suggesting rising magma

• thermal changes

• gas emissions- detectors can measure the changes and emissions of these gases.

what will well managed areas prone to volcanic eruptions have (in terms of reducing vulnerability?)

• clear evacuation and management plans drawn up

how can satellites improve the prediction of eruptions?

• can help predict earthquakes months or even years in future

• heat emissions can be detected months or years before eruptions

• satellites use thermal imaging

• however, a diverse set of tools is needed to also predict the eruptions e.g. tilt meters, gas meters

PREDICTION AND WARNING OF TSUNAMIS:

how can tsunamis be triggered?

submarine earthquakes, volcanic eruptions or landslides.

how can tsunamis be predicted?

by monitoring earthquake activity

what can prediction of tsunamis lhen lead to (in terms of reducing vulnerability)

can be used to issue warnings to vulnerable populations so they can evacuate the area

however, what are the downsides of tsunami warning systems?

many false alarms which can lead to threat denial and financial loss

PACIFIC TSUNAMI WARNING AND MITIGATION SYSTEM:

based in honolulu, Hawaii what does this system do to monitor tsunamis?

uses a series of buoys to monitor wave motion following an earthquake.

system is known as DART (Deep-ocean Assessment and Reporting og Tsunamis)

how does this system warn countries around the Pacific?

analyses data and send tsunami threat advice to communities around the world.

calculate time which a tsunami will hit these areas and get this information out to the public through text messages and national broadcasts

once a warning is issued, how do at risk countries reduce the vulnerability of the at risk population?

• immediately announce evacuation.

the indian ocean tsunami warning system (IOTWS)

why was it formed?

in response to the tragic tsunami on Dec 26th 2004 which killed over 230,000 people around the Indian ocean region

MITIGATION AND ADAPTATION OF TECTONIC HAZARDS

when looking at responses and management of hazards, a framework was developed to divide the responses into 3 categories. what are these three categories?

1. MODIFY THE EVENT altering how the physical process of the event operates and affects people and property

2. MODIFY THE VULNERABILITY- reducing the impacts on people and property

3. MODIFY THE LOSS- minimising the losses through emergency services, short and longer term aid and insurance.

MODIFY THE EVENT- EARTHQUAKES

how can earthquake events be modified?

• through hazard resistant building design creating aseismic buildings.

what two categories can aseismic design be to benefit both HIC and LIC?

high tech for HIC

low tech for LIC

where are high tech solutions usually used?

used on public buildings such as hospitals, schools and power stations as well as private sector skyscrapers

what are some examples of high tech solutions?

• computer-controlled weights on roof to reduce movement

• 'birdcage’ interlocking steel frame- steel is strong and flexible.

• rubber shock- absorbers to absorb earth tremors

what are the limitations of high tech solutions?

high tech solutions are limited as generally only wealthy economically developed nations can afford to enforce the strict seismic and building codes that can reduce death rates

what is a key problem in earthquake prone areas (retro fitting)

alot of these cities are full of older buildings that need retro fitting to bring them up to the standards of aseismic building desgin.

why is strong governance important when trying to modify the event?

in earthquake prone areas where governments enforce strict buildings codes with aseismic design feautures the reduced vulnerability can be dramatic

give two case studies where the strength of governance was strong v weak?

Loma prieta earthquake 1989 (63 people died

Haiti 2010 earthquake where over 220,000 people died due to inadequate building codes and governance.

where was low cost aseismic design used (what country)

Pakistan following an earthquake in 2005 that killed over 85,000 people and left up to 3 million homeless.

what are some examples of low cost aesismic designs?

1. currogated iron roofs- lightweight and flexible

2. quake resistant houses built out of straw. Compressed bales between layers of plastic. This is cheap, flexible and lightweight

another example of why strong governance is needed:

Building failure in Turkish Earthquake 2023?

• following the earthquake disasters in the country, Turkish construction regulations were tightened and updated in 2018 requiring structures in earthquake prone areas to use high quality concrete reinforced with steel bars (expensive)

• however it is thought that courruption has led to many new buildings not being constructed with the new standards

MODIFY THE EVENT: Volcanoes

what volcanic hazard can be controlled?

lava flows

case study of controlling lava flows: 1973 Eldafell, Iceland

1.5 billion gallons seawater sprayed onto the lava flow was successfully used to cool and solidify lava and stop it advancing onto the harbour and destroying the fishing port

Eval of this strategy?

although it successfully managed to cool and stop the lava flow event from destroying property

however, this strategy is extremely limited as it requires a lot of money which makes it impractical for widespread use and is limited

case study of controlling lava flows 2:

MT ETNA SICILY

• explosives and machinery have been successful here to create artificial channels and barriers to divert lava flows away from villages such as Rocca in mutiple eruptions from Mt Etna

eval of this strategy?

this process requires a lot of effort and machinery, which requires a lot of money.

so therefore limited to a certain area with a certain level of development

MODIFY THE EVENT: TSUNAMI

what hard engineering options are being used to provide some protection to communities at risk?

high onshore walls for protection

what did the Japanese government do after the 2011 tsunami?

• government set aside $12 billion to repair and build nearly 400km of sea walls along the northeast coast

• these new structures are taller than the ones that stood before, rising up to 14.7m in some areas, supported by foundations that are around 25 metres deep in places

overall evaluation: are expensive hard engineering strategies an option for all countries?

no, because countries like LICs wont be able to afford these strategies. The ability to implement these strategies depends on development.

also countries famous for tourism and whose economies rely on tourism may not want to implement this due to the visual impact.

MODIFY THE VULNERABILITY:

how can this be done?

• through land use planning and zoning

• Community preparedness and education

how land use planning and zoning be used to modify the vulnerability for earthquakes

• tectonic hazard risk maps identify the most at risk areas. these can then be regulated by building codes

• making sure key public buildings are not positioned in locations of greatest risk (in high risk areas put parks, open spaces and low risk areas put residential and economic developments)

how land use planning and zoning be used to modify the vulnerability for volcanoes?

• volcanic hazard flow maps to show likely routes of lava flows, flooding and pyroclastic flows to prevent building in certain areas

how land use planning and zoning be used to modify the vulnerability for tsunamis?

• rezone the coastline of tsunami-prone areas, e.g. Crescent City, California, the area along the waterfront has been developed into public parks

• houses and businesses have been moved to higher ground following a tsunami in 1964.

how can community preparedness and education modify the vulnerability?

• educate communities about precursors to hazards to look for, how to evaluate an area and how to communicate following an event

• preparing the community to cope in light of a hazard; managing the emergency services during and after the event, and have clear recommendations for action in advance of a hazard with regular drills (especially key for earthquake events that occur with little warning)

what is an example of an organisation that provides earthquake preparedness education?

The Shake Out in USA

provides education and resources to countries around the world

what are some key strategies SHAKE OUT suggests that can be adopted by everyone to, minimize vulnerability

remove objects from over your head

pack emergency kits (food,water,charger,torch)

drop and rolling during the shaking

how do japan use education and community preparedness to reduce vulnerability?

In japan, 1st September every year is called National Disaster Prevention Day

everyone practices earthquake drills: students, emergency services and hospitals

wh are community preparedness and education strategies easier to implement in HIC?

better quality education infrastructure throughout te country

MODIFY THE LOSS:

what are the two key ways to minimise the loss?

• insurance

• aid

Insurance?

mainly available for wealthier nations

however, some insurance companies will nt insure property or businesses in high risk areas

Aid?

emergency aid is key to all areas following a tectonic hazard, but in particular poorer nations where they are less likely to have planning and aid in place

who is aid provided by?

governments

NGOs

private donations

CASE STUDY SUMMARIES EVALUATION:

what does the Eyjaffjallajokull, Iceland 2010 earthquake demonstrate? (volcanic)

demonstrates how the SCALE of the hazards can impact

well prepared and management was successful in reducing social impacts, depends on the type of hazard as it still has economic impacts

what does Montserrat 1995 demonstrate (volcanic)

• shows some successful management and evacuation (government set up exclusion zones and evacuated the population)

• economic impacts due to pyroclastic flow still happened

• they were able to save lives but unable to save infrastructure

what does nevado del ruiz, Columbia 1985 demonstrate? (volcanic: lahars)

• shows ineffective management and governance of the event

• failure of management as education about the volcano was poor and the government put out a late evacuation order

what does nyiragongo, Democratic republic of Congo demonstrate (volcanic: lava flows)

• shows a comparison of LEDCs and MEDCs in the response and management of lava flows

• economic development of the country is what success depends upon.

what does mount st helens, USA demonstrate (volcanic)

• observation of eruptions and their management, highlighting the importance of monitoring and preparedness.

• the eruption however, was a lateral eruption and didnt erupt out of the main vent( this meant the exclusion zone wasnt appropriate and SHOWS that prediction is not always accurate even in developed countries.

what did the 1989 Loma Prieta earthquake demonstrate?

• shows how we can reduce vulnerability through modification of buildings and education and how preparedness can reduce vulnerability

• shows comparison between LIC and HIC country

• shows how natural geology can play a role in the hazard

what does the 2010 Haiti Earthquake demonstrate?

• difference in economic development can play a significant role in the impacts of hazard

• shows how poor quality governance had detrimental impacts on the preparedness.

• after this event, Haiti also had a tropical storm move into the area (shows how natural geology can increase risk)

what does the Turkey 2023 earthquake demonstrate?

• shows how corruption of government officials can have detrimental impacts on infrastructure

• shows how poor regulation of ‘earthquake-proof’ buildings can increase the vulnerability to the event

what does the indian ocean boxing day 2004 tsunami demonstrate?

• shows the importance of a tsunami warning system

• shows how the aereal extent of a tsunami can affect multiple countries and regions and how a wider aereal extent can impact the vulnerability

what does the Japan 2011 tsunami demonstrate?

shows how the preparedness of a country can reduce the vulnerability (monitoring, warning systems)

also shows how a the economic development of a country allows for reduced vulnerability

however, still had economic impacts and was extremely costly