Landslides can happen when heavy rain or floods weaken the ground by saturating soil with water.
The loosened ground can come apart and send masses of land careering down hills or cliff-edges.
Dr Mohammad Heidarzadeh, secretary general of the International Tsunami Commission, told MailOnline Norway is a prime spot for landslides because of the country’s soft clay soil.
He said: ‘The coast is made of loose clay material which when combined with heavy rainfall or intense wave action, becomes susceptible to failing and sliding.’
The scene of a landslide near Alta, Arctic Norway, seen Wednesday June 3, 2020, after a powerful landslide that took eight houses into the sea off northern Norway
Dr Heidarzadeh blamed the V-shape structure of the coast on causing a number of landslides over the years.
He added: ‘Another fact is the geomorphology of the coast and its V-shape structure. This is called Ria type coast in the technical literature. Ria type coasts are kind of a tourist attraction.’
A Ria coastline is an inlet formed when a river valley fills with water.
‘In terms of coastal resilience to disasters like this, they are problematic because the geological layers are aligned towards the sea. So if the formation is disturbed by heavy rainfall or other reasons, they tend to slide,’ he said.
Another way for the ground to become saturated is when ice melts. Norway can be covered in snow for the entire winter, but when it melts in the spring the soil can loosen.
According to the Climate Change Post, rainfall for more than three, ten or 30 days are the ‘most important parameters for triggering mudslides and landslides in southern and southwestern Norway in the past’.
It added: ‘Near-zero (freeze-thaw) events have become more frequent in most non-coastal parts of the country, especially in cold areas. More frequent near-zero events along with more heavy rainfall might trigger a larger number of rockfalls and rock slides due to decreased rock stability.’