Piton de la Fournaise
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| Piton de la Fournaise | |
|---|---|
 The erupting lava met the water of the Indian Ocean during the August 2004 eruption. | |
| Elevation: | 2631 metres |
| Coordinates: | |
| Location: | Réunion, Indian Ocean |
| Type: | Shield volcano (active) |
| First ascent: | |
| Last eruption: | 2006 |
| Easiest route: | |
Piton de la Fournaise (French "peak of the furnace") is a shield volcano on Réunion island (a French territory) in the Indian Ocean. It is currently one of the most active volcanoes in the world, along with Kīlauea in the Hawaiian Islands (Pacific Ocean) and Mount Erebus on Ross Island.
The Piton de la Fournaise is often known locally as le Volcan (the Volcano); it is a major tourist attraction of Réunion island.
Geography
The top and southwest parts of the volcano are occupied by a large caldera, the enclos Fouché, bordered by high cliffs, known as remparts. This enclosure extends to the southwest up the sea; the lower slopes are known as the grand brûlé (great burnt). Most lava eruptions occur within the enclos, an area in which no one lives.On the volcano top, inside the enclos are several craters. The topmost crater is the cratère Bory. It touches the ''cratère Dolomieu'', which is by far the wider of the two. There are many smaller craters inside the enclos. There are two notable small craters known as formica leo, named for their similar shape to the anthill built by the lion ant; they are made of gravel laid out by phreatic eruptions.
Lava streams crossing the Grand Brûlé occasionally reach the sea, with spectacular results. Some of the beaches there are of a greenish colour, because of the olivine sand resulting from oceanite lavas. The Grand Brûlé is formed of solidified lava streams from various periods; the most recent ones are nude rock, while older ones are covered by dense wild vegetation.
Eruptions
Most eruptions of the Piton de la Fournaise are of the Hawaiian kind: fluid basaltic lava flowing out, with little or no projections. Occasionally, phreatic eruptions (when lava touches ground water) occur. In the 2000s, there have been as many as two eruptions a year, making the Piton de la Fournaise one of the most active volcanos in the world.Eruptions within the enclos are mostly harmless, for the enclos has no inhabitants and little infrastructure. The lava streams are kept between the remparts; they occasionally reach the sea. The only adverse consequence is that long lava streams extending to the sea will cross and destroy the N2 highway. In the early 2000s, the highway thus was destroyed once or more times a year; road engineering services then wait for the lava to cool off and build another stretch of road. It is worth noting that for months after an eruption, the core of the lava streams is still hot enough so that in rainy weather, vapor fumes appear upon them, even very close to the road. In such circumstances, the stones on the road side can become too hot to the touch.
Eruptions outside of the enclos, however, can pose serious hazards to the population. The village of Piton-Sainte-Rose was evacuated in 1977 before being struck by a lava stream, which destroyed several buildings. The stream crossed the highway and surrounded the local church, entered the front door, then stopped without destroying the building. The front entrance was later cleared out, and the church was brought back into service under the name of Notre-Dame des Laves ("our Lady of Lava").
Monitoring
Volcanic activity is constantly monitored by geophysical sensors (tiltmeters, extensometers, differential GPS receivers, etc.). The data from those various sensors is sent to s volcanologic observatory, located in Bourg-Murat northwest of the volcano. The observatory, founded in 1978 following the Piton-Sainte-Rose scare, is operated by the Institut de Physique du Globe de Paris (Geophysics Institute of Paris), in association with CNRS and the University of Réunion. The observatory staff watches the volcano continuously.Procedures specify several levels of alert, which are decided by the prefect of Réunion on the basis of scientific reports:
- pre-alert: warnings about possible evolutions; hikers accessing the enclos are warned about possible developments;
- level 1: an eruption will occur soon; the public may not access the enclos until specialists have examined the situation and set pathways for those willing to admire the eruption;
- level 2: an eruption is occurring inside the enclos;
- level 3: an eruption is occurring or will occur soon outside of the enclos; some villages may have to be evacuated for safety.
Visit
A high quality forestry road, followed by a good track, connects the highway of the plains in Bourg-Murat to the pas de Bellecombe, where a parking lot and a snack bar are available to visitors. The pas de Bellecombe is situated over the rempart cliffs and offers a good point of view over the northeast part of the enclos.A good stairway path descends from the pas to the enclos floor. This path is closed for safety reason at the beginnings of eruptions. Then, frequent white paint marks over rocks delimit a number of footpaths ascending the Dolomieu and the Bory.
Pedestrian visit inside the enclos are required to be in good physical condition, wearing hiking shoes, with a good supply of drinking water and food. They must be prepared to exercise caution. Weather can change very quickly, moving from bright sunlight and heat (with risks of heatstroke) to dense fog with cold and rain; in foggy weather, straying from paths is very risky. Visitors are advised to take the necessary precautions for sun, heat, cold and rain and not to stray from marked paths.
An excellent, albeit expensive, way to get a good sight of the volcano is to ride in the touristic helicopter flights offered by commercial companies on the island.
The lower parts of the Grand Brûlé can be visited from the N2 highway. Lava streams that have crossed the road are indicated by signs.
External links
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