Natural Disasters Explained: Volcanoes

ShelterBox response volunteers and local Rotary club contacts assessing the need of a volcano in Indonesia this February.

ShelterBox response volunteers and local Rotary club contacts assessing the need of a volcano in Indonesia this February.

ShelterBox provides emergency shelter and vital supplies to support communities around the world overwhelmed by disaster and humanitarian crises. In the third of a series of features looking at the different types of natural disasters to which we respond, we consider the causes and impact of volcanic eruptions. 

Early this year, ShelterBox responded to a volcanic eruption from Mount Kelud on the heavily populated island of Java in Indonesia. This was the second eruption to rock the country in two weeks and resulted in the evacuation of more than 76,000 people with around 200,000 people being affected in all.

The dictionary definition of a volcano is ‘an opening in the earth’s crust from which molten lava, rock fragments, ashes, dust, and gases are ejected from below the earth’s surface’.

Volcanoes occur because the Earth’s crust is broken into 17 major tectonic plates that float on top of a hotter, softer layer in the Earth’s mantle and volcanoes are generally found where these plates are coming together or moving apart.
More than 75% of the world’s volcanoes, including Mount Kelud in Indonesia, occur along the Ring of Fire, a horseshoe shape that stretches from New Zealand, up to Alaska and down to the coasts of North and South America.

Volcanic eruptions can bring about some of Earth’s most dramatic and violent changes. Along with the ability to cause earthquakes, landslides and tsunamis, the lava, gases and debris emitted during volcanic eruptions can often destroy or change land beyond recognition.

Lava, the most well-known and visually stunning result of volcanic eruption, can reach temperatures of up to 1,200°C and will destroy or ignite everything in its path. While lava can bury buildings and farmland, it is usually possible to outrun the flow and evacuate the immediate area.

However, a much faster-moving threat comes in the form of pyroclastic flows, which are currents of hot gas and rock that hug the ground and move downhill at speeds of up to 450 miles per hour. The size of the rock can vary from tiny particles to boulders, which can flatten trees and buildings in their path. The temperatures of the material within the flow are so extreme that they will kill vegetation, animals and people instantly.

When pyroclastic flows come into contact with water they create lahars, which are mudflows with the consistency of the wet concrete. The lahars, which can be hundreds of metres wide, pick up speed and destroy everything in their path, burying land and wiping out infrastructure.

As both pyroclastic flows and lahars carry large amounts of volcanic deposits, this can lead to blocked rivers and extreme flooding, sometimes many miles downstream from a volcano.

Other erupted materials that can pose hazards are volcanic gases, such as sulfur dioxide and carbon dioxide, and volcanic ash.

Sulfur dioxide can lead to acid rain and air pollution, while high concentrations of carbon dioxide can collect in the soil, which can be lethal to vegetation, animals and people.

Mt Tuvuvur, Rabaul, East New Britain, PNG buried half of the regional capital in ash when it erupted in 1994. ShelterBox responded when it erupted again in 2006.

Mt Tavurvur, Rabaul, East New Britain, PNG buried half of the regional capital in ash when it erupted in 1994. ShelterBox responded when it erupted again in 2006.

Volcanic ash consists of tiny jagged pieces of rock and glass, which is spread over large areas by wind. The ash is abrasive, mildly corrosive and can block out sunlight.

When Mount Kelud erupted earlier this year, it sent a plume of ash ten miles into the air. The cloud continued to spread long after the eruption and travelled more than 300 miles to the west and northwest, leading to mass evacuations and the closure of seven airports.

Because the effects of volcanic eruption can be so destructive and far-reaching, ShelterBox takes great care to assess the needs of the affected communities before distributing aid.

Following the volcanic activity of Mount Kelud, a team of response volunteers travelled to Java to gain a clear picture of the disruption caused and whether ShelterBox would be needed to provide shelter for people who had left their homes. In this case, the team found that there was no unmet demand for shelter.

However, due to the frequency of volcanic activity around the world, ShelterBox is often called on to assess the needs of people living in the shadow of these geological phenomena and a team is currently in Colombia looking at the disruption caused by a volcano on the Ecuadorian border.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s