Dominica has at least 8 potentially active volcanoes. One of these is Morne aux Diables, an isolated composite cone that forms a peninsula at the extreme northern end of the island. Measuring 7 kilometers diameter at its base and rising to a height of 856 meters, Morne aux Diables (creole language name meaning "Mountain of the Devils") is composed of a central complex of Pelean domes from which lithified block and ash flow deposits radiate out in all directions. A prominent fan of these lithified deposits extends southwest from the main dome complex to the Portsmouth-West Cabrits area. This center is complicated by the presence of five parasitic domes with their flank pyroclastic deposits forming an east-west belt across the southern side of the volcano.

Age dating suggests that the main cone building activity occurred between 1.5 and 1.0 million years ago. Exposed on the volcano's flanks are a number of unconsolidated valley-fill block and ash flow deposits suggesting more recent activity. One of these deposits on the north-east flank of the volcano has been recently dated at >46,000 years B.P. (before present). Photo of >26,000 year old charcoal/wood fragment found in pyroclastic deposit on flanks of Morne aux Diables.

A large gap exists between the dates obtained for the main edifice building phase of this volcano and the younger valley-fill deposits. This suggests that Morne aux Diables could be: 1) an extinct center from the age of 2.5 to 1.5 million years that was reactivated during the later Pleistocene; 2) a center with long repose periods; or 3) could simply be an artifact of the paucity of dates from this volcano.

Although there has been no historical eruptions at Morne aux Diables, there is evidence of potential activity from this center. This includes the presence of warm, acidic, sulfate-rich springs on the summit of the volcano, hot springs on the coast and the occurrence of shallow earthquake swarms partially located beneath the volcano, the most recent being 2003 and 2009. Other periods of such increased activity were in 2000, 1893 and 1841.

A prominent feature of Morne aux Diables is the Cold Soufriere, an area of cold spring activity in the northwestern crater. This feature is manifested as several clear to milky bubbling pools covering an area of ~25 square meters with temperatures ranging from 23-32 degrees C. An unmistakably strong Hydrogen Sulfide odour is present and vegetation is absent in the immediate area.

View Geological Map of Morne aux Diables

Credits:

• Smith A.L et al: Unpublished data.
• Lindsay, J.M; Smith, A.L; Roobol, M.J; & Stasiuk, M.V. 2005. Dominica. In: Lindsay, J.M., Robertson, R.E.A., Shepherd, J.B., & Ali, S. (eds) 2005. Volcanic Hazard Atlas of the Lesser Antilles - Seismic Research Unit, The University of the West Indies, Trinidad and Tobago, W.I, 1-48.