Environment | Medio Ambiente Natural Disasters hurricanes, tornadoes, tsunamis, volcano eruptions and earthquakes.

Natural Disasters AvalanchesFloodsEarthquakes VolcanoesTornadoesTsunamis HurricanesLand slidesForest fires

What is an Avalanche? Why Do Avalanches Happen? ☛ Technically, an avalanche is any amount of snow sliding down a mountainside. It can be compared to a landslide, only with snow instead of earth. Another common term for avalanche is “snowslide” ☛ As an avalanche becomes nearer to the bottom of the slope, it gains speed and power, this can cause even the smallest of snowslides to be a major disaste ☛ An avalanche can be composed of many different kinds of snow depending on the region, temperature and weather. ☛ The snow packed down on the surface cannot support itself with all the weight. When another factor is introduced, such as a person’s step, this helps to loosen the snow and an avalanche occurs. Major temperature changes, rapid wind speed and man- made influences are the main causers of why avalanches occur. ☛ Most avalanches begin within weak layers of snow, which evolve within the snowpack or form on top of the snow and become buried. Eventually these weak layers can no longer hold up the weight on the overlying snow, and will give way causing the snow above them to break free and slide downhill.

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At the surface, it erupts to form lava flows and ash deposits. Over time as the volcano continues to erupt, it will get bigger and bigger.

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What is a Tsunami? ☛ A tsunami (Japanese for "harbour wave") is series of huge ocean waves caused by a rapid, large-scale disturbance of the sea water. ☛ Tsunamis can be caused by submarine volcanic eruptions, submarine landslides, meteor impact, and major earthquakes occuring beneath the seabed causing large vertical movements. ☛ In deep water, tsunami waves are less than a meter high, but they can travel at speeds exceeding 800 kilometres per hour and can easily cross an entire ocean basin. When they reach shallow water or narrow inlets the waves slow down and the height can build into a wall of water which causes devastation on the shore. ☛ Earthquake-induced movement of the ocean floor most often generates tsunamis. If a major earthquake or landslide occurs close to shore, the first wave in a series could reach the beach in a few minutes, even before a warning is issued.

The Pacific “Ring of Fire” is the most common place for tsunamis to happen, due to the number of volcanic eruptions and earthquakes.

 The waves of a tsunami are not the same as normal waves, which are formed by the wind. Wind waves flow in a circular fashion, the tops of the waves curling back under themselves.  The water of a tsunami wave behaves in a very different way. In deep ocean waters a tsunami wave may only be a foot high, but it can be 60 miles long and it can travel across the top of the ocean at up to 500 miles an hour. That is the speed of a jet airplane!  When the wave reaches shallower water near a coastline, the water at the bottom of the wave slows down, but water at the top keeps moving fast. The energy this produces can create a wave that rapidly increases in height, sometimes up to 100 feet high, that crashes into the coast and floods the land. The water can reach 1000 feet inland and can be strong enough to destroy houses and trees.

What is a tornado? ➜ A tornado is a violent rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes are capable of tremendous destruction with wind speeds of up to 300 mph. They can destroy large buildings, uproot trees and hurl vehicles hundreds of yards. They can also drive straw into trees. ➜ Most tornadoes form from thunderstorms. You need warm, moist air and cool, dry air. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere

Natural Disasters AvalanchesFloodsEarthquakes VolcanoesTornadoesTsunamis HurricanesLand slidesForest fires

What do these have in common? ➜ They are catastrophic events caused by nature or the natural processes of the earth ➜ They cause adverse effects to people

Disasters in Chile? List of Recent relevant earthquakes in Chile: Chile - M 9.5 Fatalities 1, Taltal, Chile - M 7.0 Fatalities La Ligua, Chile - M 7.4 Fatalities Valparaiso region, Chile - M 7.5 Fatalities offshore Valparaiso, Chile - M 7.8 Fatalities Near Coast of Northern Chile - M Chile-Argentina Border Region - M Near the Coast of Central Chile - M Bio-Bio, Chile - M Tarapaca, Chile - M 7.8 Fatalities Antofagasta, Chile - M 7.7 Fatalities Antofagasta, Chile - M Tarapaca, Chile - M Offshore Tarapaca, Chile - M Offshore Bio-Bio, Chile - M 8.8 Fatalities 547

Environment | Medio Ambiente Natural Disasters hurricanes, tornadoes, tsunamis, volcano eruptions and earthquakes.