Previous   |    Next

doi:10.2204/iodp.proc.340.204.2016

Geological setting

Montserrat is situated in the Lesser Antilles Island arc formed from the westward subduction of the North American plate beneath the Caribbean plate (Pindell and Barrett, 1990). The Lesser Antilles arc is bifurcated from Dominica toward the north, resulting in a volcanically extinct easterly arc and a volcanically active western arc. Activity is thought to have migrated to the more westerly arc during the mid-Miocene as the consequence of changing subduction dynamics (Bouysse and Westercamp, 1990).

There are four volcanic centers on the island of Montserrat. For the past 290 ky, eruptive activity has focused at Soufrière Hills, with a brief interlude of activity at South Soufrière Hills at 120–150 ka (Harford et al., 2002). Activity at Centre Hills has been dated between 950 and 550 ka and at Silver Hills between 2600 and 1200 ka (Harford et al., 2002). Volcanic activity has been characterized by dome eruptions, landslides, and small vulcanian style eruptions based on observations of recent eruptions and studies on subaerial deposits (Kokelaar, 2002; Smith et al., 2007; Roobol and Smith, 1998).

An eruption of the Soufrière Hills volcano started in 1995, causing evacuation of much of the island, including the capital city of Plymouth. At the time of writing (2015), the southern part of the island is still within an exclusion zone. The last major eruption was in February 2010. This eruption sequence comprised multiple phases of dome building and dome collapse episodes that generated pyroclastic flows. In June 2003, the largest globally documented volcanic dome collapse in historical times occurred, 210 × 10⁶ m³ of material (Trofimovs et al., 2006, 2008).

Top of page   |    Previous   |    Next