1.9 Impacts of Tectonic Hazards Flashcards
1.9a Strategies to modify the event
land-use zoning
land-use zoning is a process by which local government planners regulate how land in a community may be used (e.g. as residential, industrial, or recreational).
In areas at risk from volcanic eruptions and tsunami, land-use zoning is an effective way to protect both people and property.
The areas are divided into zones based on the likely type and level of damage from an eruption.
Land-use planners, and others, use hazard maps to make decisions about the appropriate use of land in each zone, as well as for preparatory tasks such as determining safe evacuation routes.
In areas at high risk from volcanic eruptions and tsunami
- any settlements tend to be limited, if they’re allowed at all
- certain types of structures and facilities will be prohibited, such as those that pose a risk if damaged (e.g. nuclear power stations), or those that are critical for a community to function (e.g. hospitals)
- some communities may be resettled if the risk is too high
- development in areas which provide natural protection will be limited (e.g. coastal mangrove forests, which act as buffers and reduce the impacts of tsunami waves).
Land-use zoning is common in wealthy countries, but less so in some developing countries.
1.9a Strategies to modify the event
hazard-resistant design and engineering defences
Collapsing buildings are one of the main causes of death and damage from tectonic hazards. Designing and constructing buildings that can withstand hazard events more effectively is key to protecting lives and property.
- new buildings and structures (such as bridges) can be designed to resist ground shaking during earthquakes
- the roofs of houses built near volcanoes can be sloped to reduce the amount of ash that builds up on them and thus reduce the risk of them collapsing under weight
- buildings at risk from tsunami can be elevated and also anchored to their foundations to stop them floating away
- existng buildings can be modified (called retrofitting) to make them safer, e.g. by strengthening their foundation
- protective structures, such as seawalls or retaining walls, ca be built to stop or slow the impact of tsunami waves and landslides
Not all hazard-resistant design needs to be expensive and high-tech. In Pakistan, some houses have been built from bales of straw held together by strong plastic netting so that during an earthquake the walls crack but the don’t collapse.
A modern earthquake-proof building may have
- rolling weights on roof to counteract shock waves
- panels of marble and glass flexibly anchored to steel superstructure
- reinforced lift shafts with tensioned cables
- ‘birdcage’ interlocking steel frame
- reinforced latticework foundations deep in bedrock
- rubber shock absorbers between foundations and superstructure
1.9a Strategies to modify the event
diversion of lava flow
Methods of diverting lava flows include building barriers, spraying lava with seawater and digging channels to try to divert the flows into safer directions.
In general they have been fairly ineffective
- the path taken by lava is hard to predict making it difficult to know where to build the walls or dig the channels
- the terrain has to be suitable (e.g. downward slope, so the diverted lava can easily flow away)
- stopping get lava from flowing towards one community may push it towards another
e.g. Mt Etna, Italy, 1983
1.9a Strategies to modify the event
modify the event
modify the event
1.9b Strategies to modify the vulnerability
high-tech monitoring
a
1.9b Strategies to modify the vulnerability
prediction
a
1.9b Strategies to modify the vulnerability
education
a
1.9b Strategies to modify the vulnerability
community preparedness and adaptation
a
1.9b Strategies to modify the vulnerability
modify the vulnerability
a
1.9c Strategies to modify the loss
short term aid
emergency aid includes providing food, clean water and shelter
short-term aid includes restoring water supplies and providing temporary shelter
1.9c Strategies to modify the loss
long term aid
longer-term aid includes reconstructing buildings and infrastructure, redeveloping the economy and managing programmes to reduce the impact of future disasters
1.9c Strategies to modify the loss
insurance
a
1.9c Strategies to modify the loss
the actions of affected communities
When a disaster strikes, its local people who are the first to respond and who often play an important role in the community’s recovery.
They are crucial in the immediate search-and-rescue efforts
In remote or isolated communities, it can take days or weeks for aid to arrive, so local people have to undertake the recovery steps themselves.
Community groups are also often involved in long-term strategies for rebuilding and improving resilience.
