Fire near Martigues

What the satellites measured

This fire was tracked from 23 July at 02:48 to 29 July at 04:15, that is 6 days, through 33 satellite detections. The detected extent reaches 325 ha.

Detected extent

325 ha

Cumulative power

300 MW

Peak power

47 MW

Detections

33

“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 satellite detection and are not an official assessment: only the local fire and civil protection authorities are authoritative.

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

One other fire near Martigues

Separate fires, apart in time or in space, not pieces of this one. A single municipality can have several over one summer, and the forest of Fontainebleau alone covers 172 square kilometres.

• 20 to 29 July602 ha

Follow live

The map shows active fires in 3D, with smoke plumes, forecast wind, drop zones and the live position of the Canadair, Dash 8 and Air Tractor aircraft of the French Sécurité civile.