Significant steam and ash explosions after 11 October occurred 30 October, 1, 6, and 7 November, and 5, 13, 14, 15, 17, 19, and 30 January [but see 2:2]. Two harmonic tremor events were recorded on 1 November and one on 6 November. No information on harmonic tremor is available after 7 November. [Both the number of earthquakes and seismic energy release declined after mid-November (table 5).]

Table 5. Number of earthquakes and total seismic energy release at Soufrière Guadeloupe, October 1976-May 1977. Courtesy of M. Feuillard.

Geological Summary. La Soufrière de la Guadeloupe volcano occupies the southern end of Basse-Terre, the western half of the island of Guadeloupe. Construction of the Grand Découverte volcano about 200,000 years ago was followed a Plinian eruption and caldera formation about 100,000 years later, and then by construction of the Carmichaël volcano within the caldera. Two episodes of edifice collapse and associated large debris avalanches formed the Carmichaël and Amic craters about 11,500 and 3,100 years ago, respectively. The present volcano subsequently grew within the Amic crater. The summit consists of a flat-topped lava dome, and several other domes occur on the southern flanks. Six phreatic explosive eruptions since 1690 opened radial fractures across the summit lava dome. The phreatic eruptions in 1976-77 caused severe economic disruption when Basse-Terre, the island's capital city immediately below the volcano, was evacuated.

Information Contacts: M. Feuillard, Lab. de Physique du Globe.