Within the Central Graben two calderas have formed and occupy most of the floor of the graben. The Trois Piton caldera is to the north and the Wotten Waven caldera to the south. Following the eruption of pumiceous material from these calderas, the Trois Pitons and Micotrin centers formed. Both of these are Pelean dome complexes with surrounding aprons of block and ash flow deposits (from nuées ardente type pyroclastic flows named by Alfred LaCroix when describing the 1902 eruption of Mt. Pelée ).
Arcuate cliffs truncate the southwestern flanks of the Plat Pays stratovolcano and form the eastern margin of a depression now occupied by the Morne Patates and Crabier Pelean dome complexes and their pyroclastic aprons. The villages of Soufriere and Scotts Head also lie within this structure. Although there has been much debate as to whether the structure is a caldera or a sector collapse scar, the problem was resolved by Anne Le Fraint and others in 2002 when detailed bathymetric studies revealed that not only does the collapse scar continue down to depths greater than 2000m, but three collapses have resulted in the most extensive debris avalanche fan found associated with the Lesser Antilles arc with an area of 3,500 sq.km. On the proximal part of the fan numerous megablocks up to 2.8km long and 240m high exist and it seems that Scotts Head is such a block.
For a detailed description of the seismic and geothermal activity and a discussion of the types of volcanic hazard presented by the different active volcanoes on Dominica the reader is referred to the soon to be published VOLCANIC HAZARD ATLAS OF THE LESSER ANTILLES by the SEISMIC RESEARCH UNIT of Trinidad.