Pyroclastic Flows, Block and Ash Flows, Surges and the Laacher See Eruption

Abstract

World-famous volcanic eruptions that have become embodied into our cultural heritage include the A. D. 79 eruption of Vesuvius, the 1883 eruption of Krakatau, but especially the eruption of Montagne Pelee on 8 May 1902 at 07:52 h on the Caribbean Island of Martinique. This disaster, the major natural catastrophe that heralded the twentieth century, is a symbol for the destructive potential of nature, as well as for the hubris of man, who fails to take the power of nature seriously. A famous example of the folklore of volcanic disasters (sometimes only loosely based on facts) is the story of one of the few inhabitants of St. Pierre, Augustus Ciparis, who survived the devastation of the town being incarcerated in the dungeon of the town jail (Fig.11.1). Witness reports include observations of survivors on ships anchored in the harbor of St. Pierre, some of which were capsized due to the enormous force of the blasts. Scientists, who had rushed to the scene, for the first time observed and described glowing clouds speeding down the flanks of a volcano with velocities exceeding 200 km/h greatly expanding in transit. Lacroix (188), who studied the effects of the eruption in detail, called them nuees ardentes, a term used first in the nineteenth century by Fouque, but now replaced by the terms pyroclastic flow or pyroclastic density current.