Cellular automata for simulating lava flows: A method and examples of the Etnean eruptions

Abstract

This paper presents a bidimensional cellular model for simulating lava flows and its application to the simulation of the 1986–87 and 1991–92 Etnean eruptions. Lava flow is viewed as a dynamic system based on local interactions with discrete time and space, where space is represented by square cells. Each cell is characterized by specific values (the state) of the following selected physical parameters: altitude, lava thickness, lava temperature and lava outflows toward the neighbouring cells. Lava rheology is considered indirectly through its effect on lava thickness. The boundary values constraining a simulation are those describing underlying topography, lava discharge rate, eruption temperature, solidus temperature and rheology. The Cellular Automata model has been tested against growth data for Etna's 1986–87 and 1991–92 flow fields. Even though the data set is heterogeneous, the model and real flow field show strikingly similar growth patterns. The close similarity highlights the flexibility of the Cellular Automata approach; as a matter of fact it should be noted that the cell dimension can be chosen in order to define the approximation, to which the simulation must be developed and topography can be easily updated on account of solidification thanks to the discrete specification for space and time, thus allowing the simulation of multiple flows. first deals with the reduction of the dimension of the cells from 10 m to 5 m. This scale is better adapted to the study of medium and small events. The second is linked to the evolution of the transition algorithm so as to modify certain types of behaviour, such as tunneling, not easy to simulate in the current form.