Volcanologists have identified 3 different phases in the evolution of mount Pelée volcano: an initial phase, an intermediate phase, and a modern phase...
In an initial phase, called "Paléo-Pelée" stage
, mount Pelee was a common stratovolcano
. The cone of paleo-Pelée is composed of many layers of lava flows and fragmented volcanic debris. Remains of the paleo-Pelée cone are still visible on the northern and western parts of the modern volcano.
A second stage, "intermediate phase
", started around 100, 000 years ago, after a long period of quiescence. This stage is marked by the formation of the Morne Macouba dome, then later on, the Morne Macouba caldera
During the intermediate phase, there were many eruptions which produced pyroclastic flows
. Around 25, 000 years ago, a large Southwest sector collapse occurred. This event is similar to the eruption of Mt. St. Helens in 1980.
This stage of the evolution has set up most of the actual mount Pelée cone, with pumice and pyroclastic flows deposits. More than 30 eruptions have been identified during the last 5 000 years of the volcano's activity.
3, 000 years ago, following a large pumice eruption, the Etang Sec caldera was then formed.
The 1902 eruption took place within the Etang Sec crater. This eruption produced many pyroclastic flows and formed a dome which filled the caldera.
The following eruption in 1929 formed a second dome in the Etang Sec caldera, and produced pyroclastic flows directed in the Blanche river valley. This last eruption is mainly responsible for the current morphology of mount Pelée.