By late October, extrusion of lava into Soufrière's central crater had virtually stopped. The October extrusion rate was an order of magnitude less than that of late September and two orders of magnitude less than the May rate.

The mean diameter of the lava extrusion increased by only 1.5 m between 2 and 25 October, to 870 m, and the maximum height remained ~130 m. Vigorous steaming from the lava was continuing in late October, but the number of small local earthquakes recorded by the summit seismograph had declined markedly since early October.

Geological Summary. Soufrière St. Vincent is the northernmost and youngest volcano on St. Vincent Island. The NE rim of the 1.6-km wide summit crater is cut by a crater formed in 1812. The crater itself lies on the SW margin of a larger 2.2-km-wide caldera, which is breached widely to the SW as a result of slope failure. Frequent explosive eruptions after about 4,300 years ago produced pyroclastic deposits of the Yellow Tephra Formation, which cover much of the island. The first historical eruption took place in 1718; it and the 1812 eruption produced major explosions. Much of the northern end of the island was devastated by a major eruption in 1902 that coincided with the catastrophic Mont Pelée eruption on Martinique. A lava dome was emplaced in the summit crater in 1971 during a strictly effusive eruption, forming an island within a lake that filled the crater. A series of explosive eruptions in 1979 destroyed the 1971 dome and ejected the lake; a new dome was then built.

Information Contacts: J. Tomblin, UWI.