Molten Mountain
In an explosion of molten fury, Piton de la Fournaise erupts, sending boiling rivers of lava hurtling downhill to tumble into the ocean below. At the beginning of the 1998 eruption, vents spawn along fissures, creating a wall of lava or curtain of fire. Gradually, the wall of fire collapses into a single fountain towering above the central vent. After several days the eruption turns to a quiescent lava effusion before the eruption finally comes to an end. This eruption was one of the longest of this century with 196 days duration from the beginning of March 9, 1998. The emitted volume was estimated at 50 million cubic metres, marking this eruption as one of the most voluminous during this century.
Since then the volcano has erupted every year.
Discovering the volcano
Leaving the coastal town of St. Pierre, the road immediately climbs. Bending in the trade winds, the fields of sugar cane soon give way to a wet forest. At La Plaine des Cafres, high altitude pastures, dotted with scattered volcano craters, are exactly half way between the imposing shape of the highest peak of Reunion, Piton des Neiges - Snows Peak, 3089 masl, and the volcanic moonlike landscape of La Fournaise. The last trees soon disappear and are replaced by sparse vegetation.
Discovering the volcano is very much like a journey into the unknown. Sharply bending roads lead the explorer into a different world. At the Pas des Sables, in the silence of the desert, one can view a huge moon-like plain. The site of Plaine des Sables - Sands Plain is impressive and invariably gives the irresistible feeling of walking upon ground that is both unexplored and hostile. Volcano Chisney produced countless tons of scoria on this strange nearly lifeless plain.
Crossing the hostile plain, cars stop at the viewpoint of La Fournaise, Pas de Bellecombe at 2311 m. One comes here face to face with a living volcano, a smoking mountain within approximately a 3 km distance. This is nature at its most dramatic. The main volcano cone is very close now, its majestic slopes streaked by grey and black lava flows.
From the viewpoint I take the path that shear-drops 200 metres down the Enclosure wall onto the caldera floor. The caldera called the Enclosure is a U-shaped area surrounded by high ramparts that force the lava to flow out on vast uninhabited slopes. Sometimes however the volcano takes the liberty to have a whim. It then belches its wrath out of the Enclosure, destroying villages on its route. This has happened twice in recent years, once in 1977 and once in 1986.
Once on the caldera floor, a clearly marked trial leaps across solidified lava towards the erupting volcano. The smoking hill of the Kapor crater on the north-eastern flank of the Piton de la Fournaise is visible all the way, making the difficult walk exciting.
Pahoehoe lava is quietly erupting on the slopes of Fournaise
Danger de mort
Danger of Death says the small board as one approaches the active volcano. The board reasons that the volcano is very active and as one walks over recently solidified lava tubes, they can break and one can fall into molten lava of more than 1000C. One is also advised not climb or come close to the active crater. But as I want to get as close as 5 metres to the lava flow, it is impossible to avoid crossing the lava tubes in their tens.
It is a dangerous and treacherous place. A hostile terrain, slippery footholds on jagged rocks, make navigating perilous. Ground can collapse any time without warning trapping victims with few means of escape. I walk very hesitantly over the collapsed tubes. Still very hot and the winter being very cold at the high-altitude volcano, it is a welcome foot-heater. Poisonous gases seep through cracks. Occasionally, some pockets of gas rob my lungs of oxygen, leaving me gasping for breath. The walk is becoming very difficult and I stop about 30 metres from the molten lava flow. I have no courage to walk further. Then I meet my Volcano Friend (I met him there - I left him there) and we walk together towards the flow. The adrenaline rush is very high, elevated by strong heat radiation and the smell of sulphuric gasses. Excitement overwhelms senses. I can hear a weird sound of flowing lava, like a pile of glass bottles being crushed a bulldozer.
Continuing uphill I arrive to the heart of the eruption - extremely peaceful lava erupting from the hillside with no indication of a crater. Slow extrusion of lava produces smooth-surface pahoehoe flows. Where lava reaches surface it pulses ferociously with occasional spattering. The motion of lava beneath corrugates the thin, solidified surface (ropy in appearance). A crew from the University of Reunion films this eruption, recording the details of the flow. Like pressure valves, a few red-hot spatter cones are relieving gas pressure from the underlying magma, causing the eruption to be non-violent. The escaping gases are extraordinarily noisy, making conversation impossible. The hissing sound is so loud I could not hear anything and the smell of the sulphur is very offensive.
The lava flows have turned the three kilometres of the caldera floor into an enormous delta-like flow. The panorama is very dramatic with the occasional comic scenes when lava pushes overlying crust upwards resembling humans walking in the middle of the flow. The flows heading downhill at high speeds are up to 10m wide. Like a liquid mountain, the entire hillside seems to be moving.
The slower, horizontal flows struggle to flow over the rugged terrain. Volcanic rubble often stops the lava from advancing. As a result, a lake of molten lava levels up to 3 metres above the surrounding ground. The pressure of lava eventually breaks the crust and the molten earth starts to flow towards me. Being only 5 metres from the dam wall, it seems pretty scary. However, this lava is too cold, therefore very viscous, and often blocks itself as it advances.
Walking towards the Kapor crater (meaning in the local Creole dialect Strong, Tough, Sturdy), the sulphuric smoke becomes very irritating and I start to cough incessantly. Dense streams of gas hiss from the fumaroles. Shifting winds blow the noxious clouds in different directions. Volcanologists measured up to 1% sulphuric gases contained in fumes coming out of the cracks. There is nothing more frightening in your life than to try to grasp for air. I hold my breath and wait for little bit of fresh air. All of the wet surfaces of the body, including the eyes, the nose and the mouth, can be damaged because water molecules dissolve the gases, forming acids that can cause injury.
Considering that the best way to survive is to return, the wind suddenly changes clearing the smog away. I proceed towards the cone. The foul air often returns. When walking under the Kapor crater, I observe several rocks falls. As soon as I can, I start to climb the opposite hill side of the main cone to avoid the danger of being buried under the avalanche. Continuous mushroom-like smoke blows from the crater, accompanied by jet-like sounds, suggest a vigorous eruptive activity inside.
Despite its eerie look during eruptions, La Fournaise is not a killer volcano. Its eruptive fountains are confined within fissures or craters and its lava moves slowly down its flanks, letting people ample time to escape. It is these types of volcanoes that people love to watch.
Enchanting Night
An official urges hikers, who climbed the volcano from the sea level, to return. They must reach the hiking path before the sun sets. We, who drove up the volcano, are allowed to stay for the night. With the sunset, the lava flows are becoming more illuminated. When the dark night blankets the island, gushing torrents of red-hot lava flow down the flanks of Fournaise like rivers of fire. There is no scale to measure by, no words to describe the view. Daylight deprives much of its enchanting terror, but in the darkness of the night, the incandescent glow from the rolling mass of pahoehoe lava is incredibly awesome.
Walking around is extremely difficult and dangerous. Numerous broken lava tubes require intricate legwork and keeping the balance is almost impossible. Using hand to help walking through this precarious terrain is impossible. The lava crust is too hot and too sharp to touch. Most of people sit down and watch the spectacle in silence. I join a few brave men that walk towards the site where small pahoehoe tongues struggle through the rugged terrain. Like small monsters the tongues suddenly appear from places nobody expects. Initially, a piece of solid crust collapses, exposing the red lava. The lava starts to extrude slowly like a giant snail engulfing the crust around. After a while the tongue begins to solidify and arrests its own flow. The tongue darkens, while others appear from behind the broken crusts. This theatre of fire is never-ending and never boring too. We look in enchantment. When too close (less than 2 metres) the heat radiation is unbearable. The surfaces of most pahoehoe flows are rolling or undulating. The "skin" on such flows is said to be flexible enough to support a man's weight and although the crust may bend, it does not break. However intriguing, I wouldnt try. I would rather sit there and watch the pulsating image of lava passing by. It is really an eerie sensation, very beautiful, it is all these different colours of reds, orange and yellows.
The red river of lava is pouring from a fissure below the Kapor crater. The crater itself is belching red-glared smoke.
The lava flow glows at staggering 1000C and we marvell at sheets of fire, kilometres in length, disappearing toward the costal plains. Red-hot lava flows, with large floating cinders rolling over one another down the side of the mountain, form beautiful fiery cascades. For a moment, lava is spattering at the source of the fluid lava fall from a small lava lake. A thin solidified crust covers the lake surface. Due to outflowing lava, the crust breaks and hot steam and sulphur bursts out. Then the lava lake is being refilled after a period of outflow.
Holding handkerchief over my mouth and nostrils to cut the power of the acidic fumes, I continue surveying the scene. The shimmering pahoehoe fronts advance slowly like snails. They make their unmistakable crackling sound, like a pile of broken glass in movement. The streams appear slow but they are unrelenting.
The fascinating atmosphere of night eruptions, where red and black mixes in stark contrast, is uncompromisingly addictive. I have spent three days watching the mountain run, with lava flow pulsating, spattering and flowing like a conveyor belt. It is my first erupting volcano and I have been initiated with the baptism of fire.
It is becoming increasingly cold, and, just after 22h00, the clouds move in. Everybody starts to leave. I have no torch with me, so I have to leave too. Following the crowd with torches, the fresh lavas are difficult to cross, so we advance slowly. After some 200 metres, the path over smooth old lavas allows us to walk faster. I often turn back in hope to see some lava flows. With no avail, I only see a faint reddish glow through the mist.
The 1998 Eruption
During the first weekend of March 1998, the Reunion volcanological observatory registered several seismic tremors from the depths of the Piton de la Fournaise (the Peak of the Furnace, 2632m). The volcano had already given several signs of awakening over the past year but then fell silent again. This time, however, the seismographic indications were more alarming. The observatory gave authorities two day warning of the impending crisis. It was only few hours before the eruption that short-term signs definitely signalled an impending eruption.
On Monday, 9 March 1998, between 15h05 and 15h10 a strong earthquake shook the massif of this small Indian Ocean island indicating that an eruption of the Furnace was imminent. Something must have happened but clouds soon covered the summit making observations impossible. Minutes later the first witness confirmed the news from the Pas de la Bellecombe: The volcano had erupted!
Eruptions first started from a fissure at an altitude of 2450m and quickly migrated northward to lower altitudes (1950m). The activity was focused at two fissures near the very bottom of the slope of Dolomieu and cones were forming at the place where lava fountains were most active. The lava, falling down like fireworks, started to flow slowly down the eastern slopes. A week later, cones up to 50m high were observed and lava was stationary 4 km east at an altitude of 1100m. Some of the lava fountains reached 50m heights, with a maximum temperature of 1167C.
Earthquakes at Piton de la Fournaise generally ceased after an eruption had broken out, but in this case they continued, hence the impending opening of a new eruptive fissure was forecast for the next few hours or days.
A second eruption, during the early hours of March 12, turned the south-western side of the Enclosure, giving rise to a 1.5 km flow. This much less productive eruptive fissure opened at an altitude of 2250m and built a spatter rampart 70m long, with a maximum lava temperature of 1157C.
The next few days, three fissures were active, totalling their lava output between 35-55 cubic metres per second. Venting was progressively restricted to limited stretches of three fissures where scoria cones started to grow reaching up to 40m. Activity at the three cones continued but progressively decreased until venting was restricted to Piton Kapor by 31 March. During late April, vigorous crater activity included lava fountains and gas-piston events. Eruption of the Piton de la Fournaise ended during the night between Sunday 20 and Monday 21 September 1998. This eruption was one of the longest of this century with 196 days duration from the beginning on March 9, 1998. The emitted volume was estimated at 50 million cubic metres, marking this eruption as one of the most voluminous during this century. Since then the volcano has erupted every year.
