Hazards

• A hazard is the threat of substantial loss of life, substantial impact upon life or damage to property that can be caused by an event
• The impacts of natural hazards depend on a number of general factors, such as the location of the hazard relative to areas of population and the magnitude and extent of the hazard.
• There are three main types of hazard, although each hazard has different driving forces:

  ◆ Geophysical – driven by the Earth’s own internal energy sources, for example, plate tectonics, volcanoes, seismic activity.

  ◆ Atmospheric – driven by processes at work in the atmosphere, for example, tropical storms, droughts.

  ◆ Hydrological – driven by water bodies, mainly the oceans, for example, floods, storm surges, tsunamis.
• Primary impacts are those that have an immediate effect on the affected area, such as destruction of infrastructure and buildings. Secondary impacts happen after the disaster has occurred, such as disease, economic recession and contamination of water supplies
• It is only by the presence of people that a natural event becomes a hazard. The pressure of an increasing population and subsequent demand for land has resulted in building in areas that are at increased risk.
• Fatalism

  Doing nothing can be seen as a defeatist attitude to take but it is an acceptance that hazards are natural events that we can do little to control and losses have to be accepted. In fact, interference with the natural processes can have a detrimental effect on ecosystems
• As technology increases, the methods of predicting hazardous events becomes more sophisticated. Remote sensing and seismic monitoring give clues to activity that may lead to a disaster and need to be acted upon. Advances in communications mean that information from all parts of the world can be shared and analysed quickly.
• Hazard Management Cycle

  Preparedness – large-scale events can rarely be prevented from happening, but education and raising public awareness can reduce the human causes and adjust behaviour to minimise the likely impact of the hazard. Knowing what to do in the immediate aftermath of an event can speed up the recovery process. In areas of high risk, the level of preparedness will be greater than in areas where such events are rare
• Hazard Management Cycle

  Response – the speed of response will depend on the effectiveness of the emergency plan that has been put in place. Immediate responses focus on saving lives and coordinating medical assistance. Damage assessment helps plan for recovery.
• Hazard Management Cycle

  Recovery – restoring the affected area to something approaching normality. In the short term this will be restoration of services so that longer-term planning and reconstruction to the pre-event levels can begin
• Hazard Management Cycle

  Mitigation – actions aimed at reducing the severity of an event and lessening its impacts.
• Park Model

  Relief - The immediate local and possibly global response in the form of aid, expertise and search and rescue.
• Park Model

  Rehabilitation - A longer phase lasting weeks or months, when infrastructure and services are restored, albeit possibly temporarily, to allow the reconstruction phase to begin as soon as possible.
• Park Model

  Reconstruction - Restoring to the same, or better, quality of life as before the event took place. This is likely to include measures to mitigate against a similar level of disruption if the event occurs again.
• While the Earth appears to be a perfect sphere when seen from space, it is in fact a geoid. This means that it bulges around the equator and is flatter at the poles. The cause of this is centrifugal forces, generated by the Earth’s rotation.
• Oceanic Crust – an occasionally broken layer of basaltic rocks known as sima (because they are made up of silica and magnesium). More dense.
• Continental Crust – bodies of mainly granitic rocks known as sial (because they are made up of silica and aluminium).
• Together, the crust and the upper mantle are known as the lithosphere.
• The rocks in the upper mantle are solid and sit on top of the asthenosphere, a layer of softer, almost plastic-like rock.
• The core is actually made up of two parts. The outer core is semi-liquid and is mainly iron; the inner core is solid and is made up of an iron-nickel alloy.