GEOLOGY

Detailed explanation-1: -If magma is thick and sticky, gases cannot escape easily. Pressure builds up until the gases escape violently and explode. A good example is the eruption of Washington’s Mount St. Helens. In this type of eruption, the magma blasts into the air and breaks apart into pieces called tephra.

Detailed explanation-2: -Quiet Eruptions Volcanoes that have very hot, low-silica magma generally erupt quietly. In a quiet eruption, lava erupts in a stream of low-viscosity lava, called a lava flow. Lava flows from a quiet eruption can travel for great distances.

Detailed explanation-3: -The molten rock is called magma. Within the Earth, the weight of rock causes pressure to increase with depth (imagine the weight, or pressure, on your body if a million rocks were sitting on top of you!). The greater the depth, the greater the pressure.

Detailed explanation-4: -Magma contains dissolved gases, which provide the driving force that causes most volcanic eruptions. As magma rises towards the surface and pressure decreases, gases are released from the liquid portion of the magma (melt) and continue to travel upward and are eventually released into the atmosphere.

Detailed explanation-5: -As a result of its higher viscosity and gas content, intermediate magma builds up pressure below the Earth’s surface before it can be released as lava. This more gaseous and sticky lava tends to explode violently and cools as andesite rock.