Volcanic eruptions have caused some of the worst disasters in the world. They can wipe out entire cities and kill thousands of people. The name of volcano comes from Roman term. It derives from Vulcan which is the name of Roman fire god. Romans believed that Vulcan lived on a volcanic Italian coast. Romans called the island Vulcano. According to scientists, volcanic eruptions are divided in to four basic groups. They are commonly known as Hawaiian, Strombolian, Vulcanian, and Peleean. The term of Hawaiian eruptions are named after the volcanoes in Hawaii. These volcanic eruptions are the least violent type.
They produce highly fluid lava which flows quietly. This gradually builds up a shield volcano. Strombolian eruptions are named after Stromboli. These result from the constant release of gas from the magma. As the gas escapes, it produces tephra that piles up, turning into a cinder cone. Strombolian eruptions happen when sticky magma plugs the central vent. This makes the magmatic gas build up pressure until it blasts. The magma is turned into volcanic dust and bombs. Vulcanian eruption which comes from the ancient Roman belief, are more violent than the strombolian eruption.
Vulcanian eruption happens and brings magma which is more viscous. Vulcanian explosions are usually larger and noisier than the Strombolian eruptions. Paleean eruptions are famous as the most violent kind of volcanic eruptions. The name of Paleean comes from the eruption of Mount Pelee, Martinique in 1902. It killed almost 38 thousands people. A Peleean eruption occurs when the magmatic gas build up tremendous pressure. This causes violent explosions with glowing clouds of hot ash and dust. Tornadoes are known as one of the most damaging disasters.
A tornado is a very powerful column of winds which spirals around a center of low atmospheric pressure. A tornado will look like a large black funnel which hangs down from a storm cloud. The name “tornado” derives from the Latin “tonare”. It means “to thunder. ” While the Spanish developed the word into “tornear” which means “to turn or twist”. T his is why a tornado is sometimes called twister or cyclone. The winds inside a twister can spin around at speeds up to 500 miles an hour, but it usually travels at roughly 300 miles an hour.
This speed twisting makes a tornado the most dangerous storm. The average tornado has a diameter of about 200 to 300 yards. The smaller tornadoes are known as satellite tornadoes. These small offspring, about 50 yards acro ss, can be very fierce and do lots of damage. The forming of a tornado can be very quick. Sometimes it can form in a minute or less. A tornado can travel across the ground at high speeds, then it can sudden ly vanish. Most tornadoes last less than twenty minutes and travel less than 15 miles. However, the super storms sometimes travel over 100 miles before they are exhausted.