Watt, Morne

Geography & Climate

Watt, Morne is located in Dominica, within the Lesser Antilles Volcanic Arc of the broader Middle America-Caribbean Volcanic Regions. Situated at 15.31° N, 61.30° W in the Northern Hemisphere, the volcano lies within a tropical climate zone. With a summit elevation of 1,224 meters above sea level, Watt, Morne is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Watt, Morne sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Dominica near Watt, Morne, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Watt, Morne has 5 recorded eruptions in the geological database, spanning from 1800 BCE to 1997 CE. The most powerful recorded event was an explosive event producing ash plumes up to several kilometers in 1880 CE, reaching VEI 2 on the Volcanic Explosivity Index. This eruption frequency indicates a moderately active volcanic system with periodic reawakenings. The most recent eruption in 1997 CE places this volcano within the modern era of volcanological observation.

Significance

With 5 recorded eruptions on file, Watt, Morne has enough documented activity to help scientists identify patterns in its eruptive behavior. Given its recent activity, Watt, Morne is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

Morne Watt (Watt Mountain) volcano lies SE of the Trois Piton/Micotrin lava-dome complex in SE Dominica, E of the capital city of Roseau. The two best-known volcanic features on Dominica, the Valley of Desolation and the Boiling Lake thermal areas, lie on the flank; both are major tourist attractions within the national park. Morne Anglais stratovolcano lies 4 km SW of Morne Watt. Soufrière Hills volcano, with dated pyroclastic-flow producing eruptions ~10,000 years ago, lies 3 km E. A major eruption from Morne Watt producing pyroclastic flows occurred ~1300 years ago. A moderately large phreatic explosion took place at the Valley of Desolation thermal area NE of Morne Watt in 1880, when ash fell over a 4-km-wide sector at the coast, 10 km from the vent. A smaller phreatic explosion occurred in July 1997, when ashfall was confined to the Valley of Desolation area. These mark the only known historical eruptions on the island.

— Smithsonian Institution, Global Volcanism Program