sábado, 31 de octubre de 2009

Pompeii: The last day - Pompeya: el último día

Está actividad fue publicada en curso pasado en Nothig de Nothig, uno de nuestros Blog de Aula de la Sección Europea. Trata de manera interdisciplinar los contenidos asociados al estudio de las manifestaciones de la energía interna terrestre en 2º curso de la ESO. Plantea actividades iniciales de motivación (un texto histórico de Plinio el Joven y un corto vídeo sobre la vida en Pompeya); de desarrollo (localización geográfica de la ciudad, su relación con las placas tectónicas, estructura volcánica y diferentes tipos de voclanes) y de autoevaluación (test final).




"You could hear women lamenting, children crying, men shouting. There were some so afraid of death that they prayed for death. Many raised their hands to the gods, and even more believed that there were no gods any longer and that this was one unending night for the world."
—Pliny the Younger, circa A.D. 97 to 109














WHAT HAPPENED HERE

August 25, A.D. 79

It all lasted 19 hours.

Then, there was only a long, deathly silence. Pompeii lay buried for nearly 1,700 years. It wasn't until 1748 that archaeologists began slowly uncovering the ancient city, preserved under 9 feet of volcanic ash and frozen in time by Pliny the Younger's vivid report.

About three-fifths of the city has been liberated from the solidified volcanic ash and pumice that engulfed it. But many questions remained unanswered for a long time.

What was life like under the volcano? What exactly did happen that summer day in A.D. 79? Here we take a look into the latest findings.



WHY IS VESUVIUS LOCATED WHERE IT IS? GLOBAL PERSPECTIVE






Vesuvius is near a place where one section of the Earth's surface is being pushed down below another section. These sections are called plates. When plates grind against one another two things can result--earthquakes and volcanoes. Volcanoes begin to form when the rocks of the lower plate get pushed deep into the Earth. There they are heated, until they melt, forming magma, one kind of liquid rock. Because magma is less dense than the solid rock around it, it is pushed upward. If this magma finds a weak place at the Earth's surface, it may break through and form a volcano.

Subduction

WHAT KIND OF VOLCANO IS VESUVIUS? VOLCANO TYPES




Vesuvius is a stratovolcano (or composite volcano), made up of alternate layers of ash and lava. Stratovolcanoes normally have two different kinds of eruptions. One kind produces mostly ash and cinders. The other kind produces lava. In Vesuvius these two types of eruption have not been seen to happen together.


INSIDE A VOLCANO





This is a type of volcano called a stratovolcano. You can see how this very tall volcano has been built up by layers of ash and lava from previous eruptions. The volcano is currently dormant. But it is about to re-awaken!

Because it is lighter than solid rock, magma (molten rock) has been rising to form a huge pool, called a magma chamber, beneath the volcano. The volcano will erupt when gases held within the magma burst out explosively, now that they are under less pressure than when the magma was deeper within the earth.

The explosive escape of the gases from the magma causes a violent eruption which literally "blows the top" off the volcano. Gas, blobs of magma (now called lava), chunks of rock, and fine debris called volcanic ash are blasted upwards. (The ash, because it is very light, may reach heights sufficient to endanger jet airplanes.)




Because the fragments of rock and ash (pyroclastics) are heavier than air and may not mix with enough air to remain high aloft, they may surge down the sides of the volcano as dangerous "pyroclastic flows."

Within the flow, heavier particles sink and the lighter particles and gases are displaced upwards. The flow meanwhile surges along like a boiling cloud. Pyroclastic flows can travel at speeds greater than 100 miles per hour and can be as hot as the inside of a kiln. Such flows killed 29,000 people in the 1902 eruption of Mount Pelée, Martinique.

WOULD YOU SURVIVE?

The volcanic eruption of Mount Vesuvius in A.D. 79 caught most of the Roman population off guard. Would you have made it?


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