logging in or signing up GEOGRAPHY PROJECT theDDNJ Download Post to : URL : Related Presentations : Let's Connect Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 155 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: August 06, 2010 This Presentation is Public Favorites: 1 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript Slide 1: Volcanoes Parts of a Volcano : Parts of a Volcano Slide 3: Volcanoes are formed when there is a crack in the crust and magma starts to flow out. Lava then cools to form the first layer. Following eruptions happen over time thus, building up slopes of the volcano. How Volcanoes are formed Different dangers of volcanoes : Different dangers of volcanoes People may suffocate due to inhaling the volcanic ashes and poisonous gases. Flying rocks that are still molten on the inside. Lava / *Pyroclastic flows. *Pyroclastic flows : They are hot ashes flowing down the mountain at rapid speed. Slide 5: Active: Volcanoes that might erupt anytime. E.g. Sakurajima &Kilauea(Hawaii) Dormant: Volcanoes that have not erupted for a long time. E.g. Mount Fuji(Japan) Extinct: When there are no records of it erupting. 3 Types of Volcanoes Slide 6: Some volcanoes explode very violently, destroying everything in their reach within minutes, while other volcanoes release lava so slowly, that you can safely walk all around. There are three types of volcanoes: Active, Dormant, Extinct. More Information : Results of what happened to Pompeii after a pyroclastic flow Slide 8: Composite (Stratovolcano): It has steep slopes and lava cools rapidly, building up high slopes. It usually has secondary pipes. Shield Volcano: Gentle slopes and lava is more liquid and flows faster. 2 different forms of volcanoes Slide 9: Close Monitoring of active volcanoes to identify sudden changes in a volcano’s behaviors. Early warning systems and evacuation routes Barriers and channels constructed to redirect flow of lava or protect themselves from danger. Precautions Slide 10: When the molten lava cools down, it hardens and gradually turns into fertile soil for farmers to plant crops. The area becomes a tourist attraction Precious rocks like diamonds can be found. Increase land mass after an eruption. Advantages of living near a Volcano Slide 11: Take away people’s lives. Destroy the settlement of villagers living there. Change the environment Disadvantages of living near a volcano Slide 12: There are 3 types of crustal movements: Convergent, transform and divergent respectively. Convergent: Plates moving towards each other forming volcanoes and fold mountains. Divergent: Plates moving away from each other forming rift valleys and ocean trenches. Transform: Plates sliding past each other, forming fault lines and causing earthquakes. Crustal movements Slide 13: The main vent is a hole that is in the volcano and when the volcano is ready to erupt the lava is at the top of the main vent. The magma goes up the main vent slowly while it is still getting hotter. When the magma is about half way up the main vent it turns into lava. Lava is a very hot liquid which burns the remaining rocks from the magma. The lava slowly continues up the main vent. While going up the lava continues to get hotter and hotter. (continue at the next page…) How a Volcano erupts Slide 14: Ash and rocks are collected as the lava gets hotter while it continues its way up the main vent. Building up pressure while lava is at the top of the main vent and the volcano erupts. The lava blasts out of the volcano along with ash, rocks, and a cloud of dust that is very thick. The ash and rock crumble to the ground, but the lava is either moving down the volcano side very slowly or at a high speed. The lava burns down almost everything in its way, and it sometimes leaves bits of things burning. The lava from the volcano can cool fast, or sometimes the lava will slowly cool down from its intense heat. A volcano literally blows its top off. One of the volcanoes that has blown its top from an explosion is Mt. St. Helens. It has erupted more than once. How a volcano erupts Slide 15: Volcanoes that are under water take a longer time than if they are on land because they are under water. The water slows down the magma and lava but if the volcano is on land the lava and magma can move quicker up the main vent. It just depends on the environment how fast the volcano can make the magma. It makes lava and the volcano makes an explosion. If the volcano is under water the cooled lava will probably make an island. The Hawaiian Islands is an example of island made by a chain of volcanoes. Water and land Volcanoes Slide 16: Mount Tambora caused one of the most massive eruption is at Sumbawa in Indonesia, which lasted from 5th April 1815 to 10th April. After the eruption, there was a heavy ash-fall. It filled the globe and prevented sunrays from reaching Earth. This caused famine and lasted for 1 year. This was called ‘The year without summer’. At least 92,000 people lost their lives. One of the largest Eruptions Slide 17: Question: What was the biggest volcanic eruption in history? Answer: History only gets you back so far, but let's see. The biggest eruption since the rise of science.The year 1800, would be Tambora in 1815. The biggest one we have direct written records of would be Santorini, around 1630 BCE. However, the Taupo eruption of New Zealand in the year 186 was larger—only no one lived there at the time. Question: What are volcanoes? Answer: The word "volcano" comes from the Roman God of Fire, Vulcanus. Also the small volcanic island of Vulcano in the Eolian Islands off Sicily, was called after that god. The island was highly active in Ancient times and people believed its crater was the chimney of the Vulcanus' forge, where the hot lava and ash coming out from the crater were the visible evidence of his activity to forge weapons for the other gods. FAQ’s Slide 18: Question: How do you find out if a volcano is going to erupt? Answer:Study the volcano's eruptive behaviour in the past and ideally, you also try to find out whether there were any signs of change before its eruptions. Such changes might be: unusual seismic activity (i.e. earthquakes at the volcano), visible or otherwise detectable deformation of the ground (i.e. opening of cracks, swelling of the whole mountain etc.), changes in composition and temperature of fumarolic gases and so on. Question: Which is the world’s largest volcano? Answer:The largest volcano on earth is Mauna Loa on Hawai'i Big Island. It is a massive shield volcano constructed by countless lava flows. When measured from the base to the top, the pile of lavas measures more than 17,000 m (56,000 ft)! FAQ’s Slide 19: CREDITS… Geography Project Done by: Dion Nicholas Jun Wei Danish Pictures: www.google.com You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.