Fire near Fos-sur-Mer

What the satellites measured

This fire was tracked from 9 August at 02:48 to 7 September at 15:10, that is at least 30 days: the clustering window stops there, and the fire or heat source may be older, through 889 satellite detections. The detected extent reaches 1,058 ha.

Detected extent

1,058 ha

Cumulative power

3,888 MW

Peak power, one pixel

42 MW

VIIRS and MODIS detections

889

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

Activestarted on 3 September at 17:56

1. First report3 September at 17:56

   Important incendie en bordure d'une départementale à Istres : des moyens aériens sur place · actu.fr

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.

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 30 days; beyond that, clustering would merge two successive fires in the same place.

Satellite passes in detail

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