Natural Hazards: When Nature Strikes Back

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natural hazard flood

Natural hazards are naturally-occurring events of unusual intensity. As climate change continues to alter the planet’s climate, it is difficult to distinguish between problems with natural causes, and those that are, at the core, human-made. Human activities can occasionally make hazards worse, but can seldom do much to make them better, aside from cleaning up after the fact, or getting out of the way. In this article we’ll look at the some of most common, and most devastating, of the natural hazards around us.

Perhaps the most common of all natural hazards is flooding. Most of the world lives on the flood plains of rivers and along coastlines, the areas that experience the most flooding. Despite all of our efforts to control rivers and protect shorelines, flooding is a natural event, and continues to happen despite our best efforts. Recent changes in weather patterns are altering the frequency and intensity of rainfall over much of the world, which can lead to increased localized flooding in some areas.

Despite generations of effort, flooding is still next to impossible to control. At best, a warning can be provided, so that people can get out of the way. In the long run, the best way to avoid being caught by flooding is to avoid building on a floodplain. This is part of the current US government policy on flood control. Natural wetlands and vegetation are the best barriers to flooding, and it’s in our best interests to encourage their growth, and not clear them for buildings or farms.

While severe earthquakes are not very common, they can cause tremendous amounts of damage whenever and wherever they hit. They are difficult to predict, however, and almost impossible to avoid. The best way to mitigate earthquake hazards is with due care paid to building techniques and materials, which can go a long way to making a building largely “earthquake-proof”. Even at that, though, the most powerful earthquakes will flatten pretty much anything and everything.

natural hazard earthquake

Related to the earthquake is the tsunami, which is a powerful wave created by any underwater event which displaces a large amount of water. Earthquakes and underwater slope disturbances are the most common reasons. A tsunami can travel at over 800 km/h in the open ocean, and average wave heights once it hits land are approximately 9m, though heights of up to 30m have been recorded. Tsunamis, like earthquakes, are difficult to predict, but science is getting better at detecting them before they hit the coasts. Interestingly, like floods, tsunami action can be mitigated by shore vegetation, which breaks up the wave and absorbs its energy.

Volcanoes can be explosively destructive events, like Mount St. Helens, or they can erupt continuously over long periods of time, like Mauna Loa, in Hawai’i. Volcanoes present a variety of threats, including lava flows, explosive eruptions, poisonous gases, and ash. Ash is the big killer, causing respiratory problems, blanketing fields, and choking rivers. Like earthquakes, volcanoes cannot be stopped, and predicting eruptions is difficult at best. Buildings cannot be designed to be volcano-proof, and the best form of mitigation is evacuation. Since predicting eruptions is still a tenuous proposition at best, warning times can be very short.

The warm waters of equatorial oceans and seas give rise to ideal conditions for the generation of hurricanes. These huge rotating storms can reach 1600km in diameter, with internal windspeeds of over 120 km/h. While the winds themselves can cause a great deal of destruction, most of the damage caused by a hurricane is from flooding, both from the extreme precipitation and storm surges. Storm surges are waves of water that can react 7 m or more in height, driven by the winds from the storm and the intense low-pressure system the storm travels along with. Like many natural hazards, the best defense is not to be there in the first place, but for many people that is not an option. As most hurricanes actually travel relatively slowly, at around 25-35 km/h, evacuation is the best route. Buildings can also be hurricane-proofed to an extent. Tree-planting may also be effective against storm surges and other flooding, much like against tsunamis.

There is considerable research that now suggests a link between global climate change and power and duration of hurricanes. Human actions could very well be making hurricanes worse.

Most research into natural hazards shows that there is very little humanity can do to prevent most of these hazards from occurring. For the most part, we are best served by getting out of their way. The only other recourse we have is to start getting our own house in order, replanting coastal forests, and stop fouling up the air with CO2.