Fire near Saint-Gilles

What the satellites measured

This fire was tracked from 4 September at 05:08 to 5 September at 04:24, through 10 satellite detections. The detected extent reaches 346 ha.

Detected extent

346 ha

Cumulative power

65 MW

Peak power, one pixel

22 MW

VIIRS and MODIS detections

10

These four figures cover the polar orbits alone, the ones that measure an area. The pass table below also counts geostationary detections, more frequent but too coarse for geometry, and its power column sums a whole pass where the peak above is that of a single pixel.

“Detected extent” is not “burned area”: it is the union of the ground footprints of the satellite pixels, and a 375 m pixel counts in full even when only a forest edge is burning. Compared with press figures it is in practice one and a half to three times the area reported. Detections taken at the edge of the scan swath, too coarse to measure anything at all, are excluded. These figures come from thermal detection and are not an official assessment: only the emergency services and the competent authorities are authoritative.

Timeline

Extinguishedstarted on 23 August at 18:06 · contained on 23 August at 19:04 · extinguished on 27 August at 19:10

1. Presumed over27 August at 19:10

   No further news, a day of silence for an active fire, four for a contained one, and no recent satellite detection nearby: the register closed the entry on its own. This is a presumption, not an announcement, and a new report would reopen it.

2. Reported contained23 August at 19:04

   À Alès, Vauvert et Jonquières-Saint-Vincent, trois feux contenus par les sapeurs-pompiers du Gard · actu.fr Occitanie

3. First report23 August at 18:06

   À Vauvert, un incendie ravage une exploitation agricole · Midi Libre

A "contained" fire is no longer spreading but is not out: crews remain on site and it can flare up again. Statuses and areas come from press reports and official sources, matched automatically; they are not an official record : only the prefecture and the fire service are authoritative. An entry with no news for ten days is closed automatically, and each entry's history keeps track of who announced what, and when.

Replay how the fire spread

The map is framed on this fire and loads only its detections. The timeline below covers the whole known life of the fire, from the first trace, satellite or report, to the last announcement from emergency services, and the ticks on the bar mark those announcements. Detections often stop before containment: a fire stops radiating once it stops spreading, which is exactly when it is declared contained. “1 h” shows what is burning within an hour of the chosen moment : the map then follows the power curve below and empties when it falls. “12 h” stacks twelve hours , as the home map does, where stacking avoids an empty screen between two satellite passes. Both are true, but they say different things.

The detected extent

How the radiative power evolved

One point per satellite pass: the sum of the fire radiative power measured over the fire. This is the curve that says whether the fire eased off or picked up again, which no cumulative figure shows. The window covers 3 days; beyond that, clustering would merge two successive fires in the same place.

Satellite passes in detail

One other fire near Saint-Gilles

Separate fires, apart in time or in space, not pieces of this one. A single municipality can have several over one summer, and a forest massif often covers more than a hundred square kilometres.

• on 22 July137 ha

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