Two fissures opened during the morning of 24 October on the E slope of Dolomieu Crater, within the caldera. The first fissure opened at 2,180 m altitude at 0830, and emitted an aa lava flow, which stopped the next day after traveling to 500 m altitude. The second fissure opened one hour after the first at 1,920 m altitude. Moderate explosive activity from this fissure built a single tephra cone until 26 October, when a second, immediately adjacent cone began to grow. Activity from the two cones remained fairly constant until lava fountaining began on 1 November. Fountains initially rose 200 m above the cones, but gradually declined until 10 November, when new lava covered 4 km². Fountaining re-intensified 10-13 November, and was succeeded on 14 November by effusion of basaltic lava flows, with velocities reaching 60 km/hour. No casualties or damage occurred. The eruption ended at 1250 on 17 November.

Further Reference. Kieffer, G., and Vincent, P.M., 1978, The October-November 1977 Eruption of Piton de la Fournaise (Réunion Island): A terminal eruption without terminal crater: C.R. Acad. Sci. Paris, serie D, v. 286, p. 1767-1770.

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.

Information Contacts: M. Krafft, Cernay.