Tag: earthquakes and volcanoes

The number of potentially active volcanoes on Earth is estimated to be about 1500, with 550 of these having erupted in recorded history. The total number of volcanoes throughout the entire world is unknown because not all volcanoes are accessible, known and recorded.

• Barren Island is located in the Andaman and Nicobar group of islands in India. It is the only active volcano in India.
• Hence option C is correct.

A caldera is a large depression formed when a volcano erupts and collapses. During a volcanic eruption, magma present in the magma chamber underneath the volcano is expelled, often forcefully.

Volcanic materials of various sorts are ejected through a pipe and the vent situated at the top of the pipe. The enlarged from of the volcanic vent is known a volcanic crater and caldera.

Stromboli is one of the most active volcanoes on Earth and has been erupting almost continuously since 1932. Because it has been active for much of the last 2,000 years and its eruptions are visible for long distances at night, it is known as the "Lighthouse of the Mediterranean". It is among the world's most visited volcanoes.

Mount Etna is Europe's highest and most active volcano. Towering above the city of Catania on the island of Sicily, it has been growing for about 500,000 years and is in the midst of a series of eruptions that began in 2001.

Lava flows from the volcano. Molten rock materials are generally called magma below the earth's surface while when they come out at the earth's face they are called lava. Lava is very hot and the temperature ranges between 700 to 1200 degrees Celsius.

A volcanic crater is a funnel shaped hollow at the top of the vent. It is formed as lava and gas and ash are blasted upwards from the main vent. Material falls back down to earth around the vent and slowly piles up forming a rim around it. The inside of the crater is kept clear by the force of upward moving material constantly removing any debris which falls there.

Lava is the molten rock expelled by a volcano during an eruption. A lava flow is a moving/outpouring of lava, which is created during a non-explosive effusive eruption. When it has stopped moving, lava solidifies to form igneous rock. The term lava flow is commonly shortened to lava. Although lava can be up to 100,000 times more viscous than water, lava can flow great distances before cooling and solidifying because of its thixotropic and shear thinning properties.

Magma is an extremely hot liquid and semi-liquid rock located under Earth's surface. Earth has a layered structure that consists of the inner core, outer core, mantle, and crust. Much of the planet's mantle consists of magma. When magma flows or erupts onto Earth's surface, it is called lava.