Gino Mirocle Crisci

The simulation model SCIARA: the 1991 and 2001 lava flows at Mount Etna

Abstract Cellular Automata (CA), a paradigm of parallel computing, represent an alternative to differential equations for modelling and simulating very complex phenomena, whose evolution is based on local interactions of their constituent parts. A CA model for lava flow simulations, SCIARA (‘Simulation by Cellular Interactive Automata of the Rheology of Aetnean lava flows’) was developed and improved according to an empirical CA method for simulating macroscopic phenomena. Its last version, SCIARA-hex1, was applied to the 1991 lava flow of the 1991–1993 eruption of Etna. The simulation results are satisfying within limits to forecast the lava flow path. It was also applied during the eruption of Etna in the summer of 2001, when a new eruption threatened the town of Nicolosi. This ‘real time’ application proved that SCIARA is a reliable and flexible tool for forecasting lava flow paths and for assessing hazard in the Etnean area.

Predicting the impact of lava flows at Mount Etna, Italy

This work was sponsored by the Italian Ministry for Education, University and Research, FIRB project n° RBAU01RMZ4 “Lava flow simulations by Cellular Automata”, and by the National Civil Defence Department and INGV (National Institute of Geophysics and Volcanology), project V3_6/09 “V3_6 – Etna”.

Revisiting the 1669 Etnean eruptive crisis using a cellular automata model and implications for volcanic hazard in the Catania area

Abstract Cellular Automata provide an alternative approach to standard numerical methods for modelling some complex natural systems, the behaviour of which can be described in terms of local interactions of their constituent parts. SCIARA is a 2-D Cellular Automata model which simulates lava flows. It was tested on, validated by, and improved on several Etnean lava events such as the 1986–1987 eruption and the first and last phase of the 1991–1993 event. With respect to forecasting the surface covered by the lava flows, the best results were acceptable. The model has been used to determine hazard zones in the inhabited areas of Nicolosi, Pedara, S. Alfio and Zafferana (Sicily, Italy). The main goal of the current work in the Etnean area from Nicolosi to Catania has been the verification of the volcanic hazard effects of an eruptive crisis similar to the event that occurred in 1669. The simulation uses the volcanic data of the 1669 eruption with present-day morphology. Catania has been affected by some historical Etnean events, the most famous one being the 1669 eruption, involving 1 km 3 of lava erupted over the course of 120 days. The simulation of ephemeral vents and the use of different histories within the experiments have been crucial in the determination of a new hazard area for Catania. In fact, during the simulation the city was never affected without the introduction of ephemeral vents, proving the fact that lava tubes played a fundamental role in the 1669 Catania lava crisis.

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 Etnas 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 flexibilit...

SCIARA γ2: An improved cellular automata model for lava flows and applications to the 2002 Etnean crisis

Abstract Cellular automata are widely utilized for modelling and simulating complex dynamical systems whose evolution depends on the local interactions of their constituent parts. Simulation by Cellular Interactive Automata of the Rheology of Aetnean lava flows (SCIARA) is a Cellular Automata model for simulating lava flows; its release γ 2 introduces innovations to the empirical method for modelling macroscopic phenomena that was utilized in the previous releases. The lava flows are described as “blocks”, individuated by their barycentre co-ordinates and velocities. This approach is different from the previous releases of SCIARA and from cellular automata derived models for fluid-dynamical phenomena such as lattice-gas and lattice-Boltzmann models. Block specifications permit to obtain a more physical description of the phenomenon and a more accurate control of its development. SCIARA γ 2 was applied to the 2002 Etnean lava flows with satisfying results, obtaining better simulations in comparison with the previous releases.

Marine Antifouling for Underwater Archaeological Sites: TiO2 and Ag-Doped TiO2

Marine fouling plays a crucial role in the degradation of underwater archaeological sites. Limitation of fouling activity and its damages are one of the most critical issues for archaeologists and conservators. The common cleaning procedure, consisting in the manual removal of fouling, requires a continuous maintenance, while a proper inhibition of biological colonisation would provide a long-time protection against biofouling. On the other hand, the most used antifouling paints, especially for ship hulls, show considerable toxicity level. Since submerged archaeological sites are often included in environmental protected areas, more eco-friendly products must be used. We have explored the possibility to use titanium dioxide and Ag-doped titanium dioxide as antifouling agents. For this purpose, they have been synthetized by sol-gel method, and then XRD, XPS, and reflectance spectroscopy measurements have been carried out to gain structural information. The powders have been dispersed in a polymer and then applied to marble surface to evaluate the chromatic alteration induced by the treatments. By means of biological tests, it was possible to assess their behaviour as biofouling agents. Results show a decreasing of biofouling activity on treated stony surfaces.

Analysing Lava Risk for the Etnean Area: Simulation by Cellular Automata Methods

The model SCIARA, based on the “Cellular Automata” paradigm, is a versatile instrument whose scope is to analyse volcanic risk from lava flows.The possible fields of intervention are:[(a)] Long term forecasting of the flow direction at various eruption rates and points of emission by locating potential risk areas and permitting the creation of detailed maps of risk;[(b)] The possibility to follow the progress of an event and predict its evolution;[(c)] The verification of the possible effects of human intervention on real or simulated flows in stream deviation.A risk scenario has been developed for the Etnean territories of the towns of Nicolosi, Pedara and S. Alfio, simulating possible episodes with different vent locations along the fracture opened in the 1989 eruption and successively activated in the 1991–1993 eruption.The main characteristics of lava flows, that might be dangerous to the inhabited areas, have been analysed on the basis of the carried out Cellular Automata.

An analysis of the black crusts from the Seville Cathedral: A challenge to deepen the understanding of the relationships among microstructure, microchemical features and pollution sources

The Cathedral of Seville is one of the most important buildings in the whole of southern Spain. It suffers, like most of the historical buildings located in urban environments, from several degradation phenomena related to the high pollution level. Undoubtedly, the formation of black crusts plays a crucial role in the decay of the stone materials belonging to the church. Their formation occurs mainly on carbonate building materials, whose interaction with a sulfur oxide-enriched atmosphere leads to the transformation of calcium carbonate (calcite) into calcium sulfate dihydrate (gypsum) which, together with embedded carbonaceous particles, forms the black crusts on the stone surface. To better understand the composition and the formation dynamics of this degradation product and to identify the pollutant sources and evaluate their impact on the stone material, an analytical study was carried out on the black crust samples collected from different areas of the building. For a complete characterization of the black crusts, several techniques were used, including laser ablation inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy, micro infrared spectroscopy, optical and scanning electron microscopy. This battery of tests provided information about the nature and distribution of the mineralogical phases and the elements within the crusts and the crust-substrate interface, contributing to the identification of the major pollution sources responsible for the deterioration of the monument over time. In addition, the results revealed a relation among the height of sampling, the surface exposure and the concentration of heavy metals. Finally, information has been provided about the origin of the concentration gradients of some metals.

Pyroclastic flows modelling using cellular automata

Cellular automata (CA) and derived computational paradigms represent an alternative approach to differential equations to model and simulating complex fluid dynamical systems, whose evolution depends on the local interactions of their constituent parts. A new notion of CA was developed according to an empirical method for modelling macroscopic phenomena; its application to PYR, a CA model for simulating pyroclastic flows, generated PYR2, which permitted an improvement of the model and a more efficient implementation. PYR2 was utilised for the 1991 eruption of Mt. Pinatubo in the Philippines islands and for the 1996 eruption of the Soufriere Hills in the Montserrat Island. Results of the simulations are satisfactory if the comparison between real and simulated event is performed, considering the area involved by the event and the variations of thickness of the deposit, as generated by collapsing volcanic columns.

A new methodological approach for the chemical characterization of black crusts on building stones: a case study from the Catania city centre (Sicily, Italy)

Mineralogical, petrographic and chemical analyses were carried out on black crusts covering the stone surface of monuments and buildings of the historical city centre of Catania, one of the most beautiful Baroque places in eastern Sicily. Black crusts were studied through the careful and synergic employment of traditional techniques, including polarizing optical microscopy (POM), scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS), and infrared spectroscopic techniques (FT-IR), in combination with an innovative technique, i.e.laser ablation inductively coupled mass spectrometry (LA-ICP-MS). The validity of such an integrated approach to study black crusts has been recently demonstrated by the authors. The main goal of this study was to develop and test the reliability of the LA-ICP-MS method on black crusts in order to evaluate the degree of chemical contamination of examined stones and to determine the role of the different sources of pollution in Catania, both anthropogenic (domestic heating, industrial combustion, vehicular traffic) and natural (emissions by Mt Etna) in the formation of crusts. Results obtained demonstrated that this innovative approach has a double potential in the study of black crusts, since it allows the analysis of alteration and degradation processes induced by migration of specific chemical elements from the crust to substrate, and, at the same time, it represents a reliable indicator of the environmental pollution.