Continuous extensometer and inclinometer variations have occurred since the beginning of April, and increased seismic activity has been recorded since the end of May. A short seismic crisis with 126 recorded events started at Piton de la Fournaise on 11 June 2001 at 1327. At 1350 extensometer variations indicated that a new eruption had started on the ESE flank, in the same area as the previous eruption on 27 March 2001. En echelon fissures started at about 2,500 elevation on the S flank, 200 m below the Dolomieu summit caldera. More fissures were located between 2,000 and 1,800 m elevation on the E flank at the southern base of crater Signal de l'Enclos and N of the Ducrot crater. Several lava flows descended the Grand Brûlé but their progression was very slow; at 1700 the front of the lava flow was still located at an elevation of 1,450 m. On the morning of 12 June, only the lower fissure at 1,800 m elevation was still active. It was ~200 m long, with several lava fountains 20-30 m high. The lava flow followed the northern border of the 27 March eruption and reached about 400 m elevation in the Grand Brûlé.

Geological Summary. Piton de la Fournaise is a massive basaltic shield volcano on the French island of Réunion in the western Indian Ocean. Much of its more than 530,000-year history overlapped with eruptions of the deeply dissected Piton des Neiges shield volcano to the NW. Three scarps formed at about 250,000, 65,000, and less than 5,000 years ago by progressive eastward slumping, leaving caldera-sized embayments open to the E and SE. Numerous pyroclastic cones are present on the floor of the scarps and their outer flanks. Most recorded eruptions have originated from the summit and flanks of Dolomieu, a 400-m-high lava shield that has grown within the youngest scarp, which is about 9 km wide and about 13 km from the western wall to the ocean on the E side. More than 150 eruptions, most of which have produced fluid basaltic lava flows, have occurred since the 17th century. Only six eruptions, in 1708, 1774, 1776, 1800, 1977, and 1986, have originated from fissures outside the scarps.

Sources: Observatoire Volcanologique du Piton de la Fournaise (OVPF), Observatoire Volcanologique du Piton de la Fournaise (OVPF)