Outline :- Introduction Process of volcanic eruption Types of volcanic eruption Reasons of volcanic eruption Effect of volcanic eruption Safety tips
Introduction A volcano is a mountain where lava (hot, liquid rock) comes from a magma chamber under the ground. Most volcanoes have a volcanic crater at the top. When a volcano is active, materials come out of it. The materials include lava, steam, gaseous sulphur compounds, ash and broken rock pieces. Worldwide, 50 to 60 volcanoes erupt each year.
Process of eruption Volcanic activity, or volcanism, is directly related to plate tectonics, and most active volcanoes are located near plate boundaries. As spreading or sinking lithospheric plates interact with other Earth materials, magma, or molten rock, including a small component of dissolved gases, mostly water vapor and carbon dioxide , is produced. Magma that has emerged from a volcano onto Earth’s surface is called lava. Approximately two-thirds of all active volcanoes on Earth are located in the “ring of fire”.
Types of volcanic eruption Cylinder cone Shield Volcanoes Composite Cones or Stratovolcanoes Lava Dome
Reasons of volcanic eruption Due to Density-difference in Magma Pressure of Released Gases Injection of New Magma
Due to Density-difference in Magma
Pressure of Released Gases
Injection of New Magma
Effects of volcanic eruption
Safety tips As much as possible, stay away from active volcanoes. If you live near an active volcano, keep goggles and a mask in an emergency kit, along with a flashlight and a working, battery-operated radio. Know your evacuation route. Keep gas in your car.
IF A VOLCANO ERUPTS IN YOUR AREA Evacuate only as recommended by authorities to stay clear of lava, mud flows, and flying rocks and debris. Avoid river areas and low-lying regions. Before you leave the house, change into long-sleeved shirts and long pants and use goggles or eyeglasses, not contacts. Wear an emergency mask or hold a damp cloth over your face. If you are not evacuating, close windows and doors and block chimneys and other vents, to prevent ash from coming into the house. Be aware that ash may put excess weight on your roof and need to be swept away. Wear protection during cleanups.
reference http://www.nationalgeographic.com/environment/natural-disasters/volcano-safety-tips/ Introduction to Environmental Geology Edward keller K. S. Valdiya , Environmental Geology: Indian Context