THE CATANIA 1669 LAVA ERUPTIVE CRISIS: SIMULATION OF A NEW POSSIBLE ERUPTION 1 Crisci, G. M., 2 Di Gregorio, S., 1 Rongo, R., 1 Scarpelli, M, 2 Spataro, W. 1 Department of Earth Sciences, 2 Department of Mathematics {dig, rongo, spataro}@unical.it University of Calabria, Arcavacata, I-87036 Rende (CS), Italy Calvari, S. International Institute of Volcanology Piazza Roma, 2, I-95123 Catania, Italy ABSTRACT SCIARA ( Smart Cellular Interactive Automata for modeling the Rheology of Aetnean lava flows, to be read as “shea’rah”), our first two-dimensional Cellular Automata model for the simulation of lava flows, was tested and validated with success on several lava events like the 1986/87 Etnean eruption and the last phase of the 1991/93 Etnean one. Real and simulated events are satisfying within limits to forecast the surface covered by the lava flow. Moreover, improved versions have been adopted in testing other real lava flows of Mount Etna and of Reunion Island (Indian Ocean). The model has been applied with success in the determination of risk zones in the inhabited areas of Nicolosi, Pedara, S. Alfio and Zafferana (Sicily). The main goal of the present work has been the verification of the effects, in volcanic risk terms, in the Etnean area from Nicolosi to Catania, of a eruptive crisis similar to the event that occurred in 1669, as if the episode would happen nowadays. Catania has been severely interested in some major Etnean events in history, the most famous one being, namely, the 1669 eruption, involving 1 km 3 of lava during 130 days. The simulation of lava tubes and the usage of different histories within the experiments have been crucial in the determination of a new risk area for Catania. In fact, simulations carried out without the introduction of lava tubes, never involved the city, proving the fact that lava tubes, played a fundamental role in the 1669 Catania lava crisis. 1. INTRODUCTION In the past, the behaviour of many complex phenomena was investigated only from a qualitative perspective, when the formal models, describing them, were so hard that the main (at that time) computational modality, represented by the integration of differential equations, was impracticable. Consequently to the development of Computer Science in these years, the applicability limits have been elevated considerably because of the continuous rise of computing power; at the same time researches in Parallel Computing evidenced the relevant potentialities of Parallel Computing models to represent a valid alternative to Differential Calculus in the description of complex phenomena [1]. Cellular Automata (CA) capture the peculiar characteristics (Petitot [2] calls this property acentrism) of systems, which may be seen to evolve according exclusively to local interactions of their constituent parts [3, 4]; they guarantee computational universality, furthermore, modelling main aspects have been widely investigated from a theoretical viewpoint [5, 6].