The lower density sometimes allows them to flow over higher topograph hi hirrents are fully dilute; for example, during the eruption of Mount Pelée in 1902 a fully dilute current overwhelmed the city of Saint-Pierre and killed nearly 30,000 people.
The lower density sometimes allows them to flow over higher topographic features such as ridges and hills. Fronts of some pyroclastic density currents are fully dilute; for example, during the eruption of Mount Pelée in 1902 a fully dilute current overwhelmed the city of Saint-Pierre and killed nearly 30,000 people.