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Table 1 Alert level usage, descriptions and response advice given in JIR on 28 and 29 March 2007

From: Newspaper reporting of the April 2007 eruption of Piton de la Fournaise part 1: useful information or tabloid sensationalism?

Alert Level Advice
Vigilance Volcanique
(Volcano Watch)
“pre-alert”
“the possibility of an eruption at any time, in the days or weeks come”
(Martel-Asselin 2007d)
“This phase essentially aims to alert the state services to the case of an imminent eruption (Gendarmerie Service, County Fire and Relief, NFB, DDE, etc.). Consequently, there is no need to be alarmed and stockpile(!); Although one must not ignore the risk of activity outside of ‘enclos’. The response plan provides for the evacuation of inhabited areas if necessary (examples: Sainte-Rose 1977, Saint-Philippe 1986, Bois White 2002). But, be rest assured that, for now, this is not an issue”
(Martel-Asselin 2007e).
“Access to the ‘enclos’ remains authorized during the “pre-alert”, thus this phase relates essentially to hikers, who are encouraged to keep their eyes open and to remain alert to any unexpected event”
(Martel-Asselin 2007e).
Alert 1 “In the case of a seismic crisis and the ascent of magma towards the surface, alert 1 for an imminent eruption is issued and the ‘enclos’ is evacuated”
(Martel-Asselin 2007d).
Alert 2 “Alert 2 corresponds to magma arriving at the surface in a few minutes or within several hours … … … if the crisis aborts, then we return to a the phase of pre-alert”
(Martel-Asselin 2007d).
In case of a sudden eruption before evacuation can occur “Keep in mind that eruptions often start at the top of the volcano, inside the Dolomieu crater, and eruptive fissures frequently intersect the path that goes around the crater. In such cases, the only solution is to simply retrace ones steps by carefully following the trail. Do not risk going off of the track; on the slopes, you have every chance of getting lost in the very difficult terrain. If you feel that you are in real trouble, it is better to stay in a high area, and to move away without excessive haste. The edge of eruptive craters are particularly fragile: already destabilized, as demonstrated by the existing cracks, they may collapse (especially) because of the seismicity associated with the eruption”
(Martel-Asselin 2007e).