Anticipating the dynamics of chaotic maps

We study the regime of anticipated synchronization in unidirectionally coupled chaotic maps such that the slave map has its own output reinjected after a certain delay. For a class of simple maps, we give analytic conditions for the stability of the synchronized solution, and present results of numerical simulations of coupled 1D Bernoulli-like maps and 2D Baker maps, that agree well with the analytic predictions.Comment: Uses the elsart.cls (v2000) style (included). 9 pages, including 4 figures. New version contains minor modifications to text and figure

Operational volcanic ash monitoring during Etna volcanic crises

Operational systems able to monitor volcanic ash in real time and provide both critical eruption parameters and useful warnings to emergency responders and government agencies should be implemented in most volcanic observatories worldwide. Over the past ten years, more than fifty lava fountains occurred at Mt. Etna (Italy) that produced eruption columns more than 10 km a.s.l. and generated large tephra fallout around the volcano flanks. For civil protection purposes, there was the need to improve the already existing monitoring systems daily run at the Istituto Nazionale di Geofisica and Vulcanologia, mainly based on eruption scenarios (weak and strong plume scenarios). We present a new upgraded system that has multiple objectives: i) to have a fast system able to best identify the type of eruptive scenario; ii) to forecast the tephra deposit in near real time, i.e. within a few hours from the eruptive event; iii) to determine the area impacted by clasts larger than 5 cm that could severely injure hikers, guides, and volcanologists and damage infrastructures in proximity of Etna summit craters. This new system is based on the real-time estimate of column height from the analysis of images taken by SEVIRI satellite and by new calibrated cameras and using meteorological parameters obtained by local models.PublishedVienna , Austria6V. Pericolosità vulcanica e contributi alla stima del rischi

Near-Real-Time Tephra Fallout Assessment at Mt. Etna, Italy

During explosive eruptions, emergency responders and government agencies need to make fast decisions that should be based on an accurate forecast of tephra dispersal and assessment of the expected impact. Here, we propose a new operational tephra fallout monitoring and forecasting system based on quantitative volcanological observations and modelling. The new system runs at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (INGV-OE) and is able to provide a reliable hazard assessment to the National Department of Civil Protection (DPC) during explosive eruptions. The new operational system combines data from low-cost calibrated visible cameras and satellite images to estimate the variation of column height with time and model volcanic plume and fallout in near-real-time(NRT). The new system has three main objectives: (i) to determine column height in NRT using multiple sensors (calibrated cameras and satellite images); (ii) to compute isomass and isopleth maps of tephra deposits in NRT; (iii) to help the DPC to best select the eruption scenarios run daily by INGV-OE every three hours. A particular novel feature of the new system is the computation of an isopleth map, which helps to identify the region of sedimentation of large clasts (≥5 cm) that could cause injuries to tourists, hikers, guides, and scientists, as well as damage buildings in the proximity of the summit craters. The proposed system could be easily adapted to other volcano observatories worldwide.Publishedid 29876V. Pericolosità vulcanica e contributi alla stima del rischioJCR Journa

A new way to reduce the impact from tephra fallout during Etna explosive eruptions

The frequent number of explosive events at Mt. Etna, in Italy, over the last ten years, has made necessary the improvement of volcanic ash monitoring and forecasting system at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo (INGV-OE). Tephra fallout produced during Etna lava fountains largely impact the population living on the volcano flanks. In addition, during one of the most powerful paroxysms, large clasts fell in proximal areas injured tourists and hikers. To reduce risk, the Italian Department Civil Protection (DPC) asked and funded INGV-OE to do a research project finalized to three specific objectives. First, identify the plume scenario (i.e. weak plume scenario (WPS) and strong plume scenarios (SPS)) based on 1-D plume model. Second, forecast characteristics of tephra deposition using near real time observations. Third, identify the region possibly impacted by large clasts (>5 cm). Two algorithms were developed to measure the column height. One from the calibrated images of two visible cameras installed on the S and W flanks of the volcano, respectively; and the other one from satellite data using a procedure based on the computation of the volcanic plume-top brightness temperature at 10.8 mm. The analysis of lava fountains that occurred between 2011 and 2015 provided the opportunity to differentiate between weak, transitional and strong plumes. The uncertainty associated with eruption source parameters, while maintaining a fixed plume height, was also assessed. In the near future the implementation of these products into the INGV-OE - monitoring room will guarantee a better and timely information to civil protection authorities charged of risk prevention at different levels of responsibility.PublishedNapoli6V. Pericolosità vulcanica e contributi alla stima del rischi

Challenges in UV camera-based real-time SO2 flux monitoring: insights from 5 years of continuous observations at Etna ad Stromboli

The advent of UV cameras has recently paved the way to volcanic SO2 flux observations of much improved temporal and spatial resolution, and has thus contributed to expanding use and utility of SO2 fluxes in volcano monitoring. Recently, the first examples of permanent UV camera systems have appeared that are now opening the way to routine fully automated monitoring of the volcanic SO2 flux at high-rate, and continuously (daily hours only). In 2014, using funding from the FP7-ERC project “Bridge” (http://www.bridge.unipa.it/), we deployed a network of 4 permanent UV cameras at Etna and Stromboli volcanoes (Sicily) that has been operating regularly since then. Using a suite of custom-built codes, data streamed by the UV camera are automatically processed and telemetered, allowing nearly real-time visualization and analysis of SO2 fluxes. Here, we summarise the key results obtained during the last 5 years of continuous observations (2014-2018) to demonstrate potentials and challenges in real-time continuous SO2 flux monitoring with UV cameras. We show that the spatially resolved SO2 flux time-series delivered by the UV camera allow effectively tracking migration in volcanic activity from the Central to New South-East Crater (Etna), and shifts in degassing activity along the crater terrace (Stromboli). At both volcanoes, the high temporal of UV cameras allows capturing the escalation in active (strombolian) SO2 degassing that typically precedes onset of paroxysmal (Etna in 2014-2016) or effusive (Stromboli in 2014) activity, and to quantify for the first time the syn- explosive SO2 budget for larger-scale explosions, including 2 paroxysmal lava fountains (Etna) and 1 major explosion (Stromboli). We finally demonstrate the ability of our automatic camera systems to capture temporal changes in SO2 flux regime, and thus to “live” monitoring degassing and eruptive behaviors at active volcanoes.PublishedNapoli6V. Pericolosità vulcanica e contributi alla stima del rischi

The VEI 2 Christmas 2018 Etna Eruption: A Small But Intense Eruptive Event or the Starting Phase of a Larger One?

The Etna flank eruption that started on 24 December 2018 lasted a few days and involved the opening of an eruptive fissure, accompanied by a seismic swarm and shallow earthquakes, significant SO2 flux release, and by large and widespread ground deformation, especially on the eastern flank of the volcano. Lava fountains and ash plumes from the uppermost eruptive fissure accompanied the opening stage, causing disruption to Catania International Airport, and were followed by a quiet lava effusion within the barren Valle del Bove depression until 27 December. This was the first flank eruption to occur at Etna in the last decade, during which eruptive activity was confined to the summit craters and resulted in lava fountains and lava flow output from the crater rims. In this paper, we used ground and satellite remote sensing techniques to describe the sequence of events, quantify the erupted volumes of lava, gas, and tephra, and assess volcanic hazards.Publishedid 9056V. Pericolosità vulcanica e contributi alla stima del rischioJCR Journa

PyTirCam-1.0: A Python Model to Manage Thermal Infrared Camera Data

Thermal-infrared remote sensing is used to monitor and study hazardous volcanic phenomena. Thermal cameras are often used by monitoring centers and laboratories. A physical comprehension of their behavior is needed to perform quantitative measurements, which are strongly dependent on camera features and settings. This makes it possible to control the radiance measurements related to volcanic processes and, thus, to detect thermal anomalies, validate models, and extract source parameters. We review the theoretical background related to the camera behavior beside the main features affecting thermal measurements: Atmospheric transmission, object emissivity and reflectivity, camera characteristics, and external optics. We develop a Python package, PythTirCam-1.0, containing pyTirTran, a radiative transfer model based on the HITRAN database and the camera spectral response. This model is compared with the empirical algorithm implemented into a commercial camera. These two procedures are validated using a simple experiment involving pyTirConv, an algorithm developed to recover the radiometric thermal data from compressed images collected by monitoring centers. Python scripts corresponding to the described methods are provided as open-source code. This study can be applied to a wide variety of applications and, specifically, to different volcanic processes, from earth and space

First ground-based observations of mesopause temperature above the Easter-Mediterranean Part I: Multi-day oscillations and tides

The mesopause region (~90 km altitude) is the coldest region of our atmosphere, and is found at the boundary between the upper mesosphere and lower thermosphere. Ground-based spectrometers, which are sensitive to the emissions from the hydroxyl (OH*) airglow layer (lying at ~87 km altitude), are used to monitor the temperature variability within the mesosphere-lower-thermosphere (MLT), at high temporal resolution. The variability of the MLT region of the atmosphere is driven by momentum deposition from gravity waves, atmospheric tides and planetary waves. The displacement of air caused by these waves can produce strong temperature, wind and species concentration perturbations. In this study we present an analysis of 4-years of OH* rotational temperature data, acquired with the German Aerospace Center (DLR) GRIPS-10 (Ground Based Infrared P-branch Spectrometer) instrument, which was installed in Israel in November 2011. This instrument provided the first long-term ground-based observations of airglow emissions in the Eastern Mediterranean. We show the nocturnal mean temperature analysis, which includes time series as well as spectral analysis of the data. In addition, we obtain (migrating) tidal oscillation estimates from the high resolution (1 min) data, by using harmonic fitting, and we analyze the variability of planetary wave signatures in the residual temperature data, which are retrieved after the removal of the tidal harmonic fits from the data. In this analysis of the residual data we find a dominant quasi-5–7 day planetary wave influence on the mesopause temperatures above the Eastern Mediterranean

Diagnostic Multidisciplinary Investigations for Cultural Heritage at Etna Volcano: A Case Study from the 1669 Eruption in the Mother Church at the Old Settlement of Misterbianco

Misterbianco is located on the southern flank of Mt. Etna (Unesco site), in eastern Sicily (Italy). This site, also known as Monasterium Album, has a long and tormented history linked with volcanic activity of Mt. Etna and regional seismicity. This site received much attention in the 2000s when excavation works brought to light a 14th century church remains below the thick layer of the 1669 lava. This study documents the first diagnostic multidisciplinary survey performed at this site 350 years after the eruption: the investigations were performed by using techniques such as ground-penetrating radar, infrared thermography, a terrestrial laser scanner and a drone survey to analyze the site’s topography, to adequately map the hidden structures inside the building and to identify fractures and deformations in the church. Starting from the site history, we present the results of the multidisciplinary approach aimed at reconstructing the historical events that led to the damage in the church