Mudslides have killed at least 13 people in the US state of California after rain and flooding brought mud and debris onto roads and residential areas of Santa Barbara County.

The rainfall rate of more than 1.5 inches per hour in parts of Southern California overwhelmed the landscape with around half an inch per hour usually enough to trigger mudslides.

The terrain has been made more vulnerable to mudslides due to its recent wildfires. The Thomas Fire — the largest wildfire in California’s recorded history — has burned more than 281,000 acres in Santa Barbara and Ventura counties since it began in early December.

The fires made the soil unable to absorb large amounts of water — allowing the downpour to overpower the landscape.

Meanwhile, steep slopes around Santa Barbara make the area vulnerable to mudslides — with land going from thousands of feet above to sea level to sea level in just a few short miles.

Santa Barbara County had issued an evacuation order for about 7,000 residents, though many have disregarded the warning.

Last week the world’s insurers were revealed to have had to pay out a record amount due to natural disasters in 2017, with the US taking the lions share of losses, at 50 percent, driven by hurricanes Harvey, Irma and Maria.

Emergency services took to social media to share images that showed the extent of the damage.

US chat show host Oprah Winfrey, who has this week been rumoured to be considering a run for president, posted a photo to Instagram from her home in Montecito saying she was “praying for our community again in Santa Barbara”.