Chapter 1 – The Working of a Volcano

 

Volcanoes are natural wonders that inspire and provoke fear at the same time. The volcanoes were a direct channel to Hades, as seen by the Greeks. The Romans believed it as the entrance to the hell. They even think that the Roman god of fire, Vulcan, lived deep inside the mountain. The stories go in all directions, and it was impossible for the ancient man to determine the exact reason, why there was an eruption of fire from a mountain. However, they did understand such plenty of activity was ongoing underneath the earths crust.

 

Earth is a made up of several massive plates consisting of rock, sand, and other sediments. The plates move consistently in all directions and colliding with each other at times. The coalition results in earthquakes and the development of a pressure zone results in volcanic eruptions. The Hot melted rock known as magma resides beneath the plates. The magma collapse in high-pressure regions called as magma chambers. When there is an expansion in the pressure, the magma in the chamber explodes upwards in a cataclysmic event. As soon as the magma reaches the Earth's surface, it becomes lava. Apart from the release of magma from the chamber, poisonous gases also vent through the channel. The primary constituent is water vapor or steam. However, there is a possibility that the gas or the steam also contains carbon dioxide, sulphur, nitrogen, hydrogen, carbon monoxide, and chlorine. There is also a chance for the existence of other gases. Apart from the release of magma and gases, the eruption also results in shooting of red-hot fragments that come in different sizes.

 

The different types of fragments that a volcano erupts are as follows:

 

  1. Blocks - large fragments made up of lava or crustal pieces
  2. Volcanic bombs - they form during the flight, which become harder and attain the shape of a spindle as they emerge from the volcano and fly through the air
  3. Bread crust bomb - the pyroclastic resembles the French bread with large cracks in the crust
  4. Lapilli - they are broken and smaller fragments about the size of walnuts
  5. Pumice – Pumice generates due to acidic lava and has a high content of the gas that produces magma bubbles. Additionally, the presence of air spaces in the bubbles formed due to the expanding gases allows it to float in water
  6. Peles Hair - it is a material that resembles spun glass. It is similar to the synthetic material, rock wool, known for installation

 

The content of silicone dioxide is excessive in lava. The amount varies from one eruption to another. The composition falls into three categories - basic, intermediate, and acidic. The basic category has less than 52% of silicone dioxide. The intermediate category has silicone dioxide between 52% and 66%. When silicone dioxide exceeds 66%, it falls in the acidic category.

 

As soon as the magma approaches the surface of the earth through cracks, holes, or fissures, it turns into the lava that spreads and shoots the hot melted rock. In a few instances, the lava covers thousands of square miles in the form of sheets. Of the different lava types, the liquid formation is capable of reaching farther distances. After it spreads and when the eruption settles down, the lava eventually cools and turns into a hard substance. The formation is of two types – pahoe and ‘aa’ type. The pahoe has a billowy surface that is smooth and resembles huge coils of rope. The AA type has jagged blocks in different angles with sharp edges and spiny escarpments.

 

There is a possibility for the exterior of the lava flow to become hard even when the inside layer is still hot and dripping. Under such circumstances, when the middle part flows away, it forms a tubular structure. There is a possibility for the tubular structure to run for miles. The longest volcanic tubular is the Northern California that extends 13.8 miles in length. Another example of the lava tube is the one at Idaho that is capable of holding the entire town’s population of 2,500. Another interesting formation is the lava tree, which forms due to the encasement of liquid lava over a tree trunk. The tree burns, leaving the details of its bark preserved in the cooled lava.