- A volcano is a crack in the crust of a planet, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber beneath the surface. Volcanism is a process that has been occurring on Earth since the early stages of its evolution over 4 billion years ago.
- After 38 years, the world’s largest active volcano, Mauna Loa, erupted, spewing ash and debris.
A volcanic eruption’s process
- The deeper one goes beneath the Earth’s surface, the hotter it becomes.
- A geothermal gradient is the amount by which the temperature of the Earth increases with depth.
- A geothermal gradient is the flow of heat from the Earth’s warm interior to its surface.
- At a certain depth, this heat begins to melt the rocks, resulting in what geologists refer to as’magma.’
- Because magma is lighter than solid rock, it rises and collects in magma chambers.
- These magma chambers, which are found at a relatively shallow depth of 6-10 km below the surface, have the potential to cause volcanic eruptions.
- As magma accumulates in these chambers, it forces its way up through cracks and fissures in the Earth’s crust, causing volcanic eruption.
- Lava refers to the magma that surfaces on the Earth’s crust; this lava can be explosive at times.
- Chambers with the potential to cause volcanic eruptions are found at a relatively shallow depth of six to ten kilometres below the surface.
- As magma accumulates in these chambers, it pushes its way through cracks and fissures in the Earth’s crust. This is referred to as a volcanic eruption. Lava is the name given to magma that rises to the surface of the Earth’s crust.
Hawaiian volcanoes are distinct from other volcanoes.
- The majority of the world’s volcanoes form along the boundaries of Earth’s tectonic plates, which are massive expanses of our planet’s lithosphere that constantly shift and collide.
- When two tectonic plates collide, one often sinks deep beneath the other, creating a subduction zone.
- Temperatures and pressures rise as the descending landmass sinks deeper into the Earth, releasing water from the rocks.
- The water slightly lowers the melting point of the overlying rock, resulting in magma that can rise to the surface—the spark of life that can reawaken a dormant volcano.
- Not all volcanoes are caused by subduction. Another type of volcano formation is known as hotspot volcanism.
- In this case, a hotspot of magmatic activity in the middle of a tectonic plate can push up through the crust and form a volcano.
- Although the hotspot itself is thought to be mostly stationary, the tectonic plates continue their slow march to the surface, forming a line of volcanoes or islands. This mechanism is thought to be the driving force behind the Hawaiian volcanic chain.
Reasons for the explosive nature of some eruptions
- Runny magma produces less explosive volcanic eruptions, which are typically less dangerous.
- Because the magma is runny, gases can escape, resulting in a steady but relatively gentle flow of lava from the volcano’s mouth. This is the type of eruption that occurred at Mauna Loa.
- Thick and sticky magma makes it difficult for gases to escape consistently. This causes pressure to build up until a breaking point is reached.
- At this point, the gases all escape violently and simultaneously, resulting in an explosion.
- Lava blasts into the air, breaking up into tephra-like fragments. Mount Vesuvius, which destroyed Pompeii, is an example of an explosive volcano.
As urbanisation and globalisation increase, volcanoes have a greater impact on man and material. The effects have an impact on flora, fauna, and global warming, which can hasten climate change.