Introduction

Although there has been extensive study of the materials and mechanisms of pyroclastic flow and its effects on the environment surrounding a volcano, there has been relatively little detailed analysis of their effects on buildings or other structures, presumably because it is relatively rare that pyroclastic flow strikes major structures or densely populated areas. Nevertheless, there are cases that provide some information. In particular, the eruptions of Mt. Pelée in 1902, one of the few instances other than the 79 eruption of Vesuvius where pyroclastic flow has struck a city, and the 1951 eruption of Mt. Lamington, where the effects of pyroclastic flow were very well documented by Australian volcanologist G.A. Taylor [1958].

From the perspective of structural behavior, the key characteristics of a pyroclastic flow are its kinetic energy--which depends on its mass density and its velocity-- its duration, and its direction; the temperature of the flow may also be a factor. The following discussion examines the general characteristics of the Pelée and Lamington eruptions, and identifies ranges of values for the flow characteristics.