xercises
Answer the following questions briefly:
1. What are volcanoes? What are the different types of volcanic eruptions?
2. Name two different types of volcanic eruptions.
3. What are composite cones?
4. How is a crater formed?
5. How are lava plateaus formed? Give an example,
5. Name three intrusive landforms in a volcanic region.
7. Enlist some of the destructive effects of volcanoes.
3. Indicate the world distribution of active volcanoes.
9. Why is the Circum-Pacific Belt known as the 'Pacific Ring of Fire'?
Answers
1)A volcano is an opening in the earth's crust through which lava, volcanic ash, and gases escape. ... Beneath a volcano, liquid magma containing dissolved gases rises through cracks in the Earth's crust. As the magma rises, pressure decreases, allowing the gases to form bubbles..
2)There are two types of eruptions in terms of activity, explosive eruptions and effusive eruptions. Explosive eruptions are characterized by gas-driven explosions that propels magma and tephra. Effusive eruptions, meanwhile, are characterized by the outpouring of lava without significant explosive eruption.
3)Some of the Earth's grandest mountains are composite volcanoes--sometimes called stratovolcanoes. They are typically steep-sided, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their bases
4)Craters are formed by the outward explosion of rocks and other materials from a volcano. Calderas are formed by the inward collapse of a volcano's magma chamber. Craters are usually much smaller features than calderas, and calderas are sometimes considered giant craters.
5)Three intrusive landforms of the volcanic region are:
Composite volcano.
Mid-oceanic ridge.
Caldera lake.
6)Lava plateaus are formed by highly fluid basaltic lava during numerous successive eruptions through numerous vents without violent explosions (quiet eruptions). These eruptions are quiet because of low viscosity of lava, so that it is very fluid and contains a small amount of trapped gases.
7)Volcanic eruptions can cause earthquakes, fast floods, mud slides, and rock falls. Lava can travel very far and burn, bury, or damage anything in its path, including people, houses, and trees. The large amount of dust and ash can cause roofs to fall, makes it hard to breathe, and is normally very smelly.
8)Volcanoes are distributed all around the world, mostly along the edges of tectonic Plates, although there are intra-plate volcanoes that form from mantle Hotspots (eg, Hawaii). Some volcanic regions, such as Iceland, happen to occur where there is both a hotspot and a plate boundary.Aug 9,
9)The Ring of Fire, also referred to as the Circum-Pacific Belt, is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. ... The abundance of volcanoes and earthquakes along the Ring of Fire is caused by the amount of movement of tectonic plates in the area