Hazards caused by volcanoes

There are two types of hurricane flows, one being fluid and the other very sticky. The fluid flow is caused by hotter lava moving at a faster pace and being aple to spread over large masses of land. Very sticky have much cooler lava and often form lava domes because they do not have the momentum to expand as far. Many times on TV lava is shown to be extremely fast, but rarley lava is unavoidable. Unfortuntley though the lava is nearly impossible to slow or stop.

Pyroclastic density currents are created by a combinations of rock, ash and hot gases. They travel at exteme speeds often hundreds of miles per hour and are pushed by gravity. These dilute turbulents are caused when lava mixes violently with water. The currents often have trails they follow such as valleys and other land structures like those. Do to the speed and heat of these currents the lava destorys anything it comes in contacts with. An example of the destruction a pyroclastic density currents  can cause is a no entry zone on the Caribbean island of Montserrat which was one Plymouth city. Lava from the Soufrière Hills volcano caused lava domes which collapsed and taveled through valleys destroying many of the homes in the area.

Another dangerous aspect of hurricanes is pyroclastic falls or volcanoe fallouts. This occurs when fragmented rock large and small is launched from the volcanoe and falls a long distance from the volcanoe. Depending on how far the material falls from the volcanoe determines the decrease in size of the deposit. These are called Tephra falls they are not dangerous unless you are hit by one and more than likley no one would be that close to the volcanoe. The ash can cause a enourmous mount of damge including destrcustion of vegetation, parts in vehicles, can destroy delicate objects, dent medals, become embedded in wood, and contain toxic chemicals. The chemicals can cause severe damage to the nearby enviornment such as the water. If the Tephra gets wet and ends up on buildings then often it will cause the buildings to collapse due to its extreme weight. The clouds created by pyroclastic material can even block the sun and lower temperatures.

Lahars are volcanic debri mudflows they are created when the debri mixes with water, “through rapid melting of snow and ice during an eruption, from heavy rainfall on loose volcanic debris, when a volcano erupts through a crater lake, or when a crater lake drains because of overflow or wall collapse.(Jessica Ball) ” They are fast can expand to reach large amounts of land, and will run over and cover any things in its path. Fortunatley these can be forseen allowing people to escape and sometimes they can be sent in another direction.

Gases are the most harmful hazard to humans. The gases released by volcanoes are carbon dioxide (CO2), sulfur dioxide (SO2), hydrogen sulfide (H2S), fluorine gas (F2) all are potential killers in the correct situations.

 

Volcanic Hazards

Many types of hazards are associated with volcanoes

Article by Jessica Ball

http://geology.com/volcanoes/volcanic-hazards/

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