Volcano Hazards William

Volcano Hazards By William Kidd 8RG

Pyroclastic Flow What is a Pyroclastic flow? Pyroclastic flows are hot fluidized masses of rock fragments and gases that can move rapidly. Pyroclastic flows can happen in many different ways. Small Pyroclastic flows can move as fast as 10 to 30 m/s while larger flows can move at rates of 200 m/s.

Lava Flows Lava flows are the least hazardous of all results from a volcanic eruption. Lava flows don’t move very fast so people rarely get killed by them, but the lava is very hot, between 550 degrees C and 1400 degrees C. There are 2 different types of lava flows, the first one is called Pahoehoe which is smooth and looks like a blob; and the other one is called ‘a’a which is thicker than a phahoehoe, with a sharp and pointy shape.

Ash Clouds Ash clouds are serious hazards if you are in a aircraft. The famous incident in Jakarta some years ago, a BA Jumbo jet flew into the ash cloud and all four engines flamed out. On Sunday, May 18 1980 when Mt. St. Helens erupted the wall of ash clouds traveled nearly 20 kilometers outward. In the end, almost 390 square kilometers of forest was destroyed. Now you know how it is affecting far greater areas and many more people than other volcanic hazards.

Volcanic Bombs A volcanic bomb is a mass of molten rock, larger than 65 mm (2.5 inches) in diameter. Volcanic bombs are formed when a volcano ejects viscous fragments of lava during an eruption. The big rocks which you see at the back are volcanic bombs.

Poisonous Gases The type of gas that is released into the Atmosphere is water vapour(H2o) followed by Carbon dioxide(Co2) and Sulfur dioxide(So2). Volcanoes can also release other gases, such as: Hydrogen sulfide(H2s), Hydrogen(H2), Carbon monoxide (Co), Hydrogen chloride (Hcl), Hydrogen Fluoride (HF) and lastly Helium (He).

Lahars Lahars are one of the greatest volcanic hazards. They are similar to Pyroclastic flows, but contain more water. Lahars usually travel down valleys. The speed of Lahars sweeps cars off the roads. They can stream down mountains at 100 miles per hour. People cannot usually outrun a Lahars. Even if the car starts, unless they are prepared to drive 20 miles at 100 miles per hour, they still may not survive. Lahars can destroy everything in its often miles long path.

Examples Where these hazards happened and the Effects they have had Pyroclastic flow: On the 24th and 25th August AD79 the volcano, Vesuvius erupted in Italy. On the 25th a Pyroclastic flow hit the town of Pompeii, Mt. Vesuvius was 7 km away from Pompeii. Mt. St. Helens eruption included a Pyroclastic flow that swept down the mountains, flattening forests, overtaking vehicles and killing lots of people. Lahars: When Vesuvius erupted, Pompeii was buried under ash, but the nearby town Herculaneum was hit by a Lahars that totally buried the town. Lava Flows: It happened in Ethiopia, the volcanic explosion spewed out lava across a huge area of 300 sq km. Volcanic Bombs: When Mt. Asama erupted in February 2009, it was throwing rocks 1km from the crater.

Thank You for watching my presentation about: Volcano Hazards I hope you enjoyed it! Pictures: www.google.com Information: By me and a computer Sound/Music: Microsoft PowerPoint Videos: Internet Explorer Thank You!