HAZARDS OF VOLCANOES
       People normally think that when a volcano erupts that red lava will spray and flow down the sides of the volcanic mountain.  People think so because of the pictures seen on TV and in books.  Well, there are really two types of eruptions.  Explosive, like Mt. St. Helens, and effusive, like in Hawaii.  Effusive volcanoes usually result in gently flowing lava flows usually leading to the ocean, but sometimes, such as times that have occurred in the past, effusive volcanoes can go explosive.  By the Year 2000 (NOW) 500 million people will be in danger of volcanic hazards, and in the past 500 years, more than 200,000 people have already died because of volcanic eruptions.  Sometimes, when an eruption in a volcano is explosive, a Tephra occurs.  A Tephra is when an explosive volcano erupt and sends pieces of rocks streaming into the atmosphere, and when the pieces are larger than 64 mm they are considered blocks or bombs.
                                                                  CAUSES OF ERUPTIONS
    Some of the reasons that a volcano erupts are if the lava is sticky or not; because if the lava is thin and runny then the gases can escape the lava easily; and an effusive volcano occurs, and the lava is flowing out of the vents. If the lava is sticky then the gases cannot get out, an explosive volcano occurs.  When a volcano occurs, the lava that is stored in the magma chambers has risen to the surface through the pressure coming from the center of the volcano, and the volcano erupts.  Volcanoes can only occur in certain places, usually on the edge of plate boundaries.  Some volcanoes occur at hot spots, which are under the ocean.  Some islands, such as Hawaii are formed by volcanoes.  The volcanoes erupt over time and the lava that comes out and builds up and the lava eventually reaches the surface of the water.  Hawaii, in total, is taller than Mt. Everest from base to peak.
                                                            SIGNS THAT AN ERUPTION IS LIKELY
    Most volcanoes that erupt do it without warning.  Usually they give pre eruption signs, but on some rare occasions, explosive volcanoes can just erupt.  Usually ,people can tell if a volcano is about to erupt, because there will be earthquakes of increasing intensity before the real eruption.  Volcanoes can also be predicted if there is a lot of steaming and fumarolic activity before the eruption.  Seismometers are used to track earthquakes due to the rise of magma in the volcano, so they will know somewhere around the time it will erupt.  Swelling of the ground on the surface can be detected by using precision and techniques that measure minute changes in slope, distance, or elevation at the ground surface.

                                                                                      MOUNT VESUVIUS
    Mount Vesuvius is located where the African Plate meets the Eurasian Plate, near Naples, Italy.  In A.D. 79 and 1631 destroyed the cities of Pompeii and other surrounding towns.  Vesuvius is surrounded by about 3,000,000 people, and is preparing for it's next large eruption that will be a catastrophe for both human and environmental ecosystems.  The eruptions of Vesuvius are seen as many emblems, death, deluge, and the Sterminator Vesevo by Leopardi.  During the eruption, more than 2000 people died, including Pliny the Elder a Roman naturalist.
    After the eruption, it was called a plinian explosion.  That means that the sticky magma was very gas rich, viscous magma explodes deep inside a volcano, (the vent serves as a gun barrel) and a tremendous blast shooting upward at twice the speed of sound, creating a vertical column of ash 20 miles high.  When it erupted in 1631, 3000 people were killed, and 5 towns destroyed.  Since the 79 A.D., it has erupted more than 50 times and is still active.

                                                                                            MOUNT PELEE
Mount Pelee is a cone shaped volcano that is 1400 meters high.  It takes up 100 square meters on the north part of Martinique.  The eruption was easily predicted because there were many forewarnings, such as the steam coming out of the vent on April 2nd.  On April 23rd, there were many earthshocks, and a thin rain of ash fell on the city, and on the 25th ash and pumice were spit out by the volcano.  The authorities didn't warn the residents about the volcanic eruption, because they did not expect it.  On the last days of April, the volcano was still spitting ash and the gaseous smell only got worse, not better.
        On the 7th of may, the residents were startled with an enormous roar.  On top of the volcano, there were 2 vents that were glowing hot with the magma that was eager to leap out of the magma chambers.  On the next day, the volcano erupted.  Two enormous black clouds of ash (also known as nuees ardentes) were thrown out of the two vents, one going straight up and one following the slope downward.  This avalanche of heat was moving down the slope right towards St. Pierre.  Only two out of thirty thousand were able to survive the volcanic blast.
 

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