Ancient people believed that volcanoes were under the control of the gods. They believe that the volcanoes’ spectacular explosions, and eventual destruction to everything around it, are displays of the gods’ anger.

What are volcanoes?

In reality, volcanoes are vents in the Earth’s surface from which molten rock, debris, and steam are being released. There are around 1900 active volcanoes around the world, including those that have been active in historical times. Ninety percent (90%) of these are located along what we call the “Ring of Fire,” which is a band of volcanoes circling the edges of the Pacific Ocean.

How are volcanoes formed?

Most volcanoes are formed at the Earth’s plate boundaries, areas where huge slabs of rock meet in the lithosphere, the planet’s outer shell. As these land plates move and interact, they trigger a gradual series of events that can end with explosions. 

These events can happen slowly or really quick, and either the volcano grows from inside or it builds up as it adds layers of lava and ash outside of the volcano. In Mexico, a farmer finished plowing his corn field at around 4:30 p.m. when he noticed a vent open up in his field. He came back at 8:00 a.m. the next morning and found a young volcano towering 10 meters high. He witnessed the birth of Mount Paricutin.

How do volcanoes erupt?

Volcanoes erupt when magma, the molten rock deep in the Earth’s crust, rises towards the surface since its intense temperature creates pressure on the magma to push upwards. As magma comes out halfway along the volcano’s vent, it is called lava. 

As lava rises, dissolved gases and rocks are collected along the way. Once the lava reaches the top, it causes the volcano to erupt, blasting lava, rocks, and dust clouds across great distances. The lava is so hot, it burns everything that crosses its path until it slowly cools and hardens to become rocks or part of the volcano.

Two important traits that characterize volcanoes are explosiveness and viscosity. Lower amounts of dissolved gases lead to effusive, non-explosive eruptions, while high amounts of dissolved gases lead to more explosive eruptions. 

Meanwhile, magma’s silica content leads to less viscous magma. Low-viscosity magma often lets dissolving gases escape to the surface and erupting lava becomes more fluid or runny. High amounts of silica lead to high-viscosity magma, which often traps the dissolved gases. Pressure builds in the magma until the gases explode violently from the volcano’s vents.  The magma erupts as hard fragments of rock and ash.

Volcanoes typically alternate between short active periods and much longer, dormant periods. Although some volcanoes are considered extinct, almost any volcano is capable of rumbling to life again.

On that note, there are also different types of eruptions, from the slow and gradual release of lava to violent explosions that destroy the volcano itself.

When will volcanoes erupt?

Calculating the exact time of volcanic eruptions is still far from reach. However, analyzing volcanic activity helps scientists (volcanologists in particular), and residents surrounding the volcano as well, to determine whether a volcano would erupt or not. Although some volcanic eruptions occur without warning, most volcanoes provide various types of warning before eruption, such as streams of steam coming from the crater, detectable earthquakes, or changes in the temperature and chemistry of the ground and spring waters.

What is the volcano’s role in our ecosystem?

Whether the volcano is in a heavily-populated area or in a remote region, a volcanic eruption may result in staggering death tolls, as well as decimation of towns, industries, and vegetation. Lava can burn everything in its path, while volcanic ash causes breathing problems among humans and animals. And when ash is mixed with rain water, it creates a deadly surge of hot lahar flowing through rivers and towns.

However, volcanoes bring benefits as well. They provide valuable mineral deposits, fertile soil, and geothermal energy. Lava flows can even bring new land, and become home for new life.