Disasters explained: Earthquakes

Facts and figures, FAQs and everything you need to know about earthquakes

Image: Nepal 2015

Earthquakes, also known as seismic events, occur across the world every day. Most of them are too small to cause any damage.

Yet, powerful quakes can hit hard and claim thousands of lives. A high annual death toll often results from major seismic events and subsequent tsunamis and other related disasters.

We explain everything you need to know about earthquakes here.

Afghanistan earthquake June 2022


ShelterBox is monitoring the aftermath of a 5.9 magnitude earthquake that struck remote parts of south-eastern Afghanistan. It happened in the early hours of the morning of 22 June when most people were asleep at home.

The quake has left at least 1,000 people dead so far, with the death toll expected to rise.

At ShelterBox we are gathering information from all possible sources to see whether there is a need for emergency shelter, and if we are well placed to help.

We have responded in Afghanistan four times, supporting people displaced by conflict and extreme weather events, such as flooding.

FAQs

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What is an earthquake and how are they caused?


To understand what causes an seismic event, it’s important to know what tectonic plates are and how they work.

Tectonic plates cover the surface of the earth. They are slow-moving, but they get stuck at their edges due to friction. And when the stress on the edge overcomes the friction, there is an earthquake. This releases energy in waves that travel through the earth’s crust and cause the shaking that we feel.

We call the point underground where the force builds, the focus. As the strength of the force varies, so do the scale of the quakes. And that’s why some are a lot more damaging than others.

An earthquake can trigger secondary hazards or disasters, that sometimes cause far more harm. For example, this includes landslides, tsunamis and flooding.

2 people on a motorcycle pass by a tilted, destroyed building in Nepal after the 2015 earthquake
In Kathmandu, Nepal, two people on a motorcycle pass by a destroyed building, after the 2015 earthquake. Image: Emily Whitfield-Wicks

What are the impacts of an earthquake?


An earthquake can be a scary or even traumatic event for a person to experience. These are some of the impacts that a disaster like this can have.

Aftershocks

Aftershocks are smaller quakes that happen after the largest shock of an earthquake sequence. They can continue over a period of weeks, months, or years. Most powerful mainshocks cause further larger, longer and many more aftershocks.

Liquefaction

Liquefaction is a physical process that can lead to ground failure. It causes clay-free soil deposits, like sands and silts, to temporarily lose their ‘solid’ strength. Thus they behave as thick fluids rather than as solids. The effect is very much like when you wiggle your toes in the sand close to the water.

Tsunamis

A tsunami is a series of giant waves caused by earthquakes or undersea volcanic eruptions.

It sends a surge of water onto land, often reaching heights of over 100 feet. Although tsunami waves do not reach great heights out in the depths of the ocean, as they enter shallower water they begin to grow in energy and height.

Tsunami waves can tear across the sea at speeds of 500 miles an hour. The depth of the ocean determines the speed – travelling as fast as a jet plane over deep waters and slowing down when reaching shallow waters.

Landslides

A landslide is the movement of a mass of rock, debris, or earth down a slope.

How does ShelterBox help?


A family sits outside a ShelterBox tent in Haiti
A family sits outside their ShelterBox tent in Haiti, after the devastating earthquake killed thousands in 2010.

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