Tectonic Hazards, 2.5- Living with the risk from Tectonic Hazards Flashcards
Why do some people live in hazardous areas?
Large Earthquakes and Volcanic eruptions don’t happen very often. They are not seen as a great threat on people’s lives.
People living in poverty may focus on other issues daily, like food, money, security and family.
Plate Margins often coincide with very favourable areas for settlement, such as costal areas where ports have developed.
Some people may not be aware of the risks of living close to a plate margin.
Volcanoes can bring benefits such as fertile soils, rocks for building, rich mineral deposits and hot water.
Fault lines associated with earthquakes can allow water supplies to reach the surface. This is particularly important in dry desert regions.
More effective monitoring of volcanoes and tsunami waves enable many people to receive warnings and evacuate before events happen
Better building design can withstand earthquakes so people may feel less at risk.
How does Iceland benefit from Volcanic Activity?
Hot water from within the Earth’s Crust provides heat and hot water for nearly 90% of all buildings in Iceland.
Volcanic rocks are used in constructions for roads and buildings.
Iceland’s dramatic landscape with waterfalls, volcanoes and mountain glaciers has become a huge draw for tourists. Tourism provides jobs for many people.
The naturally occurring hot water- some of which reaches the surface through cracks created by Earthquakes- is used to heat greenhouses and swimming pools,
Geothermal energy is used to generate 25% of the country’s electricity(most is hydroelectric power)
Thousands of Tourists visited Iceland after the recent eruption of Eyjafjallajökull in 2010
Monitoring
Using scientific equipment to detect warning signs of events such as a volcanic eruption.
Prediction
Using historical evidence and monitoring, scientists can make predictions about when and where a tectonic hazard may happen.
Protection
Designing buildings that will withstand tectonic hazards
Planning
Identifying and avoiding places at risk.
Monitoring in Volcanoes
As magma rises through a volcano it gives a number of warning signs that an eruption is likely to occur. All of the world’s active volcanoes are closely monitored by scientists. If an eruption seems likely, warnings can be issued and action taken to evacuate surrounding areas. Modern hi-tech equipment is used, some of which is located in the volcano itself.
How do scientists monitor volcanoes?
Remote Sensing- satellites detect heat and changes to the earthquake’s shape.
Seismicity- Seismographs record earthquakes
Ground Deformation- Changes to the shape of the volcano are measured using laser beams.
Geophysical measurements- detect changes in gravity as magma rises to the surface.
Gas- instruments detect gases released as magma rises.
Hydrology- Measurements of gases dissolved in water.
Monitoring in Earthquakes
Earthquakes happen, usually with little warning. There is some evidence of changes in water pressure, ground deformation and minor tremors prior to an earthquake, scientists have yet to discover useful ways to monitor and predict an earthquake.
Prediction in Volcanoes
The prediction of a volcanic eruption is based on scientific monitoring. In 2010 an increase in earthquake activity beneath the Eyjafjallajökull ice cap in Iceland enabled scientists to make accurate predictions about the eruptions that took place in March and April that year.
Prediction in Earthquakes
It is impossible to make accurate predictions about earthquakes due to the lack of clear-warning signs. However, scientists studying historical records of earthquakes at plate margins have identified locations that they believe are at greatest risk
Protection in Volcanoes
The sheer power of a volcanic eruption means that there is often little that can be done to protect people and property. However, it is possible to use earth embankments or explosives to divert lava flows away from property. This has been done on the slopes of Mount Etna in Italy
Protection in Earthquakes
Earthquake protection is the main way to reduce risk. It is possible to construct buildings and bridges to resist the ground shaking associated with an earthquake. In Chile, new buildings have reinforced concrete columns strengthened by a steel frame. Regular earthquake drills help people keep alert and be prepared.
It is possible to construct tsunami walls at the coast to protect people and important buildings like nuclear power stations.
Planning in Volcanoes
Hazards maps have been produced for many of the world’s most dangerous volcanoes, showing the likely areas to be effected. They can be used in planning to restrict certain land uses or to identify which areas need to be evacuated when an eruption is about to happen.
Planning in Earthquakes
Maps can be produced to show the effects of an earthquake or identify those areas most at risk from damage. High value-land uses such as hospitals, reservoirs and office blocks can then be protected in those vulnerable areas.
