Disasters explained: Earthquakes and landslides

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

Image: Emily Whitfield-Wicks

Earthquakes occur across the world every day. We don’t hear about all of them, because most of them are too small to cause any damage.

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

Find out everything you need to know about earthquakes and landslides here.

Earthquakes FAQs

Open all

What is an earthquake and how are earthquakes caused?


To understand what causes an earthquake, 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. When the stress on the edge overcomes the friction, there is an earthquake that releases energy in waves that travel through the earth’s crust and cause the shaking that we feel.

The point underground where the force is created is called the focus. As the strength of the force varies, so do the scale of the earthquakes. This explains why some earthquakes are a lot more damaging than others.

An earthquake can trigger secondary hazards or disasters, that sometimes cause far more harm than the actual earthquake. Landslides, tsunamis and flooding can often cause devastation across areas impacted by an earthquake.

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

Erti's story of recovery

When the 7.4 magnitude earthquake hit Sulawesi, Indonesia in 2018, 146 houses in Erti’s village were completely turned to rubble – including her own.

They stayed in a temporary shelter for a whole month until they were given vital ShelterBox aid. Erti and her family were given a sturdy ShelterBox tent, which they set up on the land where their house once stood.

What are the impacts of an earthquake?


An earthquake, depending on how powerful it is, can be a scary or even traumatic event for a person to experience. These are some of the impacts that an earthquake can have.

Aftershocks

Aftershocks are smaller earthquakes that happen after the largest shock of an earthquake sequence. Aftershocks can continue over a period of weeks, months, or years. Most commonly, powerful mainshocks are followed by larger, longer and more numerous aftershocks.

Liquefaction

Liquefaction is a physical process that can lead to ground failure. Liquefaction causes clay-free soil deposits, like sands and silts, to temporarily lose their ‘solid’ strength and 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 speed is determined by the depth of the ocean – travelling as fast as a jet plane over deep waters and slowing down when reaching shallow waters.

Landslides

A landslide can be described as the movement of a mass of rock, debris, or earth down a slope. Keep scrolling to find out more about landslides.

What is a landslide and how are landslides caused?


Landslides are movements of mass of rock, debris or earth down a slope. They are often triggered in slopes already on the verge of movement.

Earthquakes often cause damaging landslides, but other causes can be flooding, rainfall, snowmelt, changes in water level, stream erosion, changes in groundwater, volcanic activity, or disturbance by human activities.

Earthquake shaking and other factors can also induce landslides underwater. These landslides are called submarine landslides. These sometimes cause tsunamis that damage coastal areas.

Near populated areas, landslides are a major threat to people and property. In 2016, severe flooding in Sri Lanka caused major landslides, killing over 100 people and leaving thousands homeless. ShelterBox responded to the disaster, providing tents and other emergency aid items to badly-affected communities.

A man stands on top of a pile of mud in Sri Lanka
A man is standing on top of a pile of mud, following the deadly landslide in Sri Lanka in 2016.

Where do landslides occur?

Landslides can occur anywhere. Areas most prone to landslides include steep terrain, land previously destroyed by wildfires, land that has been modified by human activity.

For example deforestation or construction, areas along rivers or streams, or any areas where surface runoff is directed, or land is heavily saturated. (source: WHO)

Escaping a deadly landslide

In 2016, heavy monsoon flooding caused a deadly landslide in Sri Lanka, burying three villages and killing 170 people.

While Nadeera and her family fled for their lives, their home was destroyed. After the disaster, Nadeera’s house stood in ruins, toothbrushes and flip flops half-buried in mud.

The mountain where the village stood was too dangerous for people to move back to their homes and, after the tragic event, not many people wanted to. Nadeera’s family were able to move into a ShelterBox camp set up in a safe area around a kilometre away.

Their ShelterBox contained all of the essentials that the family needed to start returning to normality; from kitchen utensils to water carriers and solar lights.

How does ShelterBox help?


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

Explore more


Disasters explained: Hurricanes

Find out everything you need to know about hurricanes and typhoons.

Disasters explained: tsunamis

Tsunamis can destroy lives, homes, crops and roads in the blink of an eye. Learn more about what they are, what causes them and what the effects are.

Disasters explained: volcanoes

Learn what volcanoes are, how they erupt, and the effects of a volcano eruption.

Disasters explained: Wildfires

Wildfires burn millions of acres of land every year. Find out more about what they are, their connection with climate change, and facts about the 2020 Australia bushfires.

Natural Disasters Explained

Tsunamis, earthquakes, hurricanes, floods, volcanoes – everything you need to know about disasters.

Disasters explained: floods

Floods are among the most common and devastating disasters. Read more about why they happen and their effects.