Malevolent acts or lack of vigilance, such as a discarded butt, are in the vast majority of cases responsible for fires, recalls Commander Jouassard.
The Var fire is "an extraordinary fire in terms of the speed at which it spread", with peaks of 8 km / h, which had never been recorded in France, specifies the spokesperson for the Civil security.
Climate change will increase the risk of fires and Civil Security is preparing for fires "as intense" in ten or fifteen years in the north of France.
The violent fire in the Var, which has already devastated 8,100 hectares, is still not extinguished on Thursday.
As weather conditions improve, firefighters expect a decisive day.
What are the causes of these big fires?
Commander Alexandre Jouassard, spokesperson for Civil Security, takes stock of the causes of forest fires.
What characterizes a major fire?
A major fire is differentiated first by its propagation, that is to say the size of the area burned and obviously, the direct impact for the populations.
A 500 ha fire in the middle of the countryside and a 500 ha fire with many homes directly affected do not have the same impact.
The duration of extinction is also a factor to be taken into consideration and it is often linked to the first point.
A fire that is as large as that in the Var obviously takes longer to put out.
Depending on the weather conditions, we are not allowed to leave hot spots or areas that could be reactivated by winds.
What are the causes of major fires in nature?
It is established by our statistics: 90% of forest fires are the result of human action, either a malicious act with arsonists, or by lack of vigilance with still people who throw cigarette butts, who carry out campfires, barbecues in areas where it is strictly forbidden to have hot spots.
Regarding the remaining 10%, these are natural risks.
It is often linked to lightning which can be a source of ignition and the start of fire.
Why do forest fires develop particularly in summer?
The weather conditions are unfavorable, because in recent days, we have had extreme temperatures in the Southeast.
There is also a low rate of hydrometry, that is, the level of humidity.
This is something to really take into consideration.
If the temperatures are high, but there is a lot of humidity, the forests will catch fire less quickly.
With a low hydrometry rate, which was the case in recent days, trees like stone pines ignite very quickly.
On the southern part, there was no significant water for a very long time.
The third point is the wind.
This is a very important factor because it can develop fires for a longer time and perform fire swings.
This means that when you are facing a fire, it passes quickly behind you, 300, 500, 600 m behind you, suddenly because the embers and the particles will be projected and will become sources of ignition. .
What makes the Var fire so special?
It is an extraordinary fire in the speed at which it has spread.
We had peaks at 8 km / h.
You have to imagine a flame front with building heights, 30 m high, at the speed of a person running a short jog.
It is impressive and we had not recorded these propagation speeds before in France.
In 2003, the speed of the fire in this same area was 1.5 or 2 km / h.
The area, that of the Moors, is also difficult to access.
To go inside the fire, there are no tracks and therefore, access must be created.
And the second element is this wind speed gain in the valley which is very dangerous.
If the fire rushes there, there may be a greater progression.
What are the medium-term projections concerning the risks of major fires in France due to climate change?
The 6th IPCC report last week finished driving the nail on this theme.
We obviously looked at what is happening in our European neighbors with fires of more than 50,000 ha in Sweden two years ago, in areas that are not normally sensitive to forest fires.
It is the same in Siberia.
Coordination work with Météo-France has been initiated so that we can anticipate these fires.
In the next ten or fifteen years, it is envisaged that there will be fires which could be as intense as those we have known there, but in the north of the territory, as in the Vosges, in Brittany.
This is why, this year, four bases have been created to accommodate teams in the Somme, the Vosges and Châteauroux.
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Fire in the Var: 8,100 hectares covered, times in the north, "decisive day" for firefighters
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