Why ground in south-west France is still burning from 2022 forest fire

Some parts of the ground in south-west France are still burning from a forest fire which started in 2022.

The soil of the Hostens Forest (Gironde) continues to burn from the inside - almost a year and a half after it initially started - due to the presence of an old lignite (natural coal) mine within the local soil.

The forest fires ignited this lignite within the subsoil and the combustible rock now continues to gradually burn out of the ground.

"We end up with several exits, several chimneys which evacuate the heat," Franck Uteau, an environmental engineer for the Gironde departmental council, told BFMTV.

A total of 20 hectares still have active outbreaks despite the rains of recent weeks.

Read more: Thousands evacuated as forest fire rages in south France tourist spot

Risk of new fires

Officials worry that in the event of a severe drought these could start new fires.

In an attempt to guard against such an eventuality local authorities are doubling their vigilance in the area.

In addition to the environmental risks there is also a danger for potential walkers as the collapse of ash pockets could drop a walker into an effective underground furnace.

Once the issue is resolved the department will aim to re-nature the forest.

The Gironde department and its municipalities are looking for ways to protect communities against forest fires.

Devastation of 2022

High temperatures have seen heightened forest fire warnings issued for parts of southern France in the past few years.

2022 was a particularly disastrous year, with a total of 19,821 fires burning 72,000ha across the country.

Four major wildfires hit Gironde in the summer of 2022. The last was a huge wildfire which burned around 3,500 hectares of forest in September that year.

The blazes forced around 1,800 locals to flee the area, particularly from the villages of Saumos and Sainte-Hélène, west of Bordeaux.

Read more: Gironde wildfire update: 1,200 locals evacuated, 3,600 hectares burned

Human carelessness and littering

In the past 15 years, there have been on average 15,000 wildfires each year, 90% of which are of human origin.

The public are advised to never smoke in forests, woods, or dry vegetation areas and to never discard cigarette butts in nature.

They are also reminded not to have barbecues or fires close to any vegetation and not to carry out mechanical work close to dry grass or vegetation.

Finally residents must clear their land of dry or built-up vegetation (débroussaillement) which is mandatory in some areas to reduce the risk of fire.

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