Natural Hazards & Disasters:
A natural hazard is a threat of a naturally occurring event that will have a negative effect on people or the environment. A natural disaster is a major adverse event resulting from natural processes of the Earth; examples include floods, volcanic eruptions, earthquakes, tsunamis, and other geologic processes. A natural disaster is the aftermath of an natural hazard and can cause loss of life or property damage, and typically leaves some economic damage in its wake, the severity of which depends on the affected population's resilience, or ability to recover. What is a bushfire? A bushfire is a wildfire that burns out of control spreading across vegetated regions of bushland. In order for a bushfire to be catastrophic, the right conditions must be present. Most bushfires happen in times when temperatures are high. In addition, conditions must be dry. Areas with dense undergrowth, as can be found in south-eastern Australia, are the most vulnerable to bushfire. There are many causes of bushfires – some result from natural events, some are deliberately lit and others are accidental and avoidable man made causes. Bushfires can originate from both human activity and natural causes with lightning the predominant natural source, accounting for about half of all ignitions in Australia. Fires of human origin currently account for the remainder and are classified as accidental or deliberate. Fires lit deliberately can be the result of arson or designed to achieve a beneficial outcome but experience sudden adverse weather conditions which results in their uncontrollable spread. Bushfires often start when dry winds blow inland from central Australia. While the winds bring dry weather, they also provide ventilation for the flames. Trees such as eucalypts are especially prone to fire because their leaves have a highly flammable oil. Dry leaves and bark are especially flammable. Where do they occur? The Australian climate is generally hot, dry and prone to drought. At any time of the year, some parts of Australia are prone to bushfires with the widely varied fire seasons reflected in the continent’s different weather patterns. For most of southern Australia, the danger period is summer and autumn. For New South Wales and southern Queensland, the peak risk usually occurs in spring and early summer. The Northern Territory experiences most of its fires in winter and spring. |
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