Claudia Spinetti

Mt. Etna tropospheric ash retrieval and sensitivity analysis using moderate resolution imaging spectroradiometer measurements

A retrieval of tropospheric volcanic ash from Mt Etna has been carried out, using measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS). The NASA-MODIS satellite instrument acquires images in the 0.4 to 14 μm spectral range with a spatial resolution of 1 km at nadir. The eruption which occurred on 24 November 2006 is considered as a test case in this work. In order to derive the ash plume optical thickness, the particle effective radius and the total mass, the Brightness Temperature Difference procedure has been applied to MODIS channels 31 (centered at 11 μm) and 32 (centered at 12 μm). Channel 5 (centered at 1.24 μm) has been used to refine the cloud discrimination, exploiting the distinct reflectivity of meteorological and volcanic clouds in the near infrared spectral range. The detection of volcanic ash pixels has been significantly improved by applying an atmospheric water vapor correction to MODIS data. This procedure doubles the number of pixels identified as containing volcanic ash compared to the original method. The retrieved mean ash optical thickness at 0.55 μm, mean particle effective radius and the total ash mass in the plume are 0.4, 3.5 μm and 3620 tons, respectively. A detailed sensitivity analysis has been carried out to investigate errors in the retrieval caused by the uncertainty in various parameters: surface temperature and emissivity, plume geometry (altitude and thickness), ash type and atmospheric water vapor. Results show that the largest contributions to retrieval errors are from uncertainty in surface parameters, aerosol type and atmospheric water vapor. The total tropospheric volcanic ash retrieval errors are estimated to be 30%, 30% and 40% for mean AOT, mean effective radius and total mass retrieval, respectively.

Mt. Etna volcano high-resolution topography: airborne LiDAR modelling validated by GPS data

ABSTRACT High-resolution digital topography is essential for land management and planning in any type of territory as well as the reproduction of the Earth surface in a geocoded digital format that allows several Digital Earth applications. In a volcanic environment, Digital Elevation Models are a valid reference for multi-temporal analyses aimed to observe frequent changes of a volcano edifice and for the relative detailed morphological and structural analyses. For the first time, a DTM (Digital Terrain Model) and a DSM (Digital Surface Model) covering the entire Mt. Etna volcano (Italy) derived from the same airborne Light Detection and Ranging (LiDAR) are here presented. More than 250 million 3D LiDAR points have been processed to distinguish ground elements from natural and anthropic features. The end product is the highly accurate representation of Mt. Etna landscape (DSM) and ground topography (DTM) dated 2005. Both models have a high spatial resolution of 2 m and cover an area of 620 km2. The DTM has been validated by GPS ground control points. The vertical accuracy has been evaluated, resulting in a root-mean-square-error of ± 0.24 m. The DTM is available as electronic supplement and represents a valid support for various scientific studies.

Volcaniclastic flow hazard zonation in the Sub-Apennine Vesuvian area using GIS and remote sensing

Steep slopes mantled by pyroclastic deposits are favorable areas prone to generate hazardous volcaniclastic flows. In Italy, such a setting is well represented in the Campania Region, where pyroclastic deposits from the explosive activity of the Neapolitan volcanoes (Ischia, Campi Flegrei, and Somma-Vesuvius) cover the Apennine range bordering the Campanian Plain. In order to provide a useful contribution to the mitigation and prevention of these calamitous natural events, this work presents a multidisciplinary approach to improve the understanding of the volcaniclastic flow hazard zonation in an Apennine area of 340 km 2 surrounding the Somma-Vesuvius volcano. The disruption proneness index (DPI) was calculated in order to identify the drainage basins potentially prone to generate volcaniclastic flows. This index is obtained by combining satellite and morphometric data in a geographic information system (GIS) environment. It is calculated for 1100 drainage basins, considering the main parameters influencing the slope stability (slope angle, basin shape factor, curvature, relative relief, aspect, and land cover). The land cover mapping is obtained from Landsat data and airborne high-resolution images, while the morphometric parameters are derived from a digital elevation model (DEM) with a cell size of 10 m. The result is a zonation map that classifies the drainage basins according to different degrees of proneness to generate volcaniclastic flows (low, moderate, high, and very high). The drainage basins falling within high and very high classes are 66%, while 28% fall in the moderate class, and the remaining 6% fall in the low proneness class.

Volcanic ash retrieval at Mt. Etna using Avhrr and Modis data

The volcanic ash detection procedures are based on Brightness Temperature Difference (BTD) algorithm using the thermal infrared channels centred around 11 and 12 microns of a multispectral satellite sensor. The Mie code has been is included in the retrieval procedure to compute the ash optical properties from the ash microphysical characteristics. The simulations has been carried out using MODTRAN radiative transfer model. The Nasa-Modis and the Noaa-Avhrr measurements of Mt. Etna eruptive plume occurred in November 2006 have been analyzed to retrieve the plume optical thickness, the particle effective radius and the size distribution.

Mt. Etna volcanic plume from ASTER and HYPERION data by ASI-SRV modules

Volcanic plumes represent a visible indicator of volcanic activity. They vary in space and time, strongly influenced by the quiescent or eruptive status of the volcano. Different volcanic activities, such as volcanic clouds and plumes, inject into the atmosphere gases and aerosol at different latitudes, altitudes and with different times of residence. Released by the magma, plumes are a turbulent mixture of gases, solid particles and liquid droplets, emitted at high temperature continuously from summit craters, fumarolic fields or during eruptive episodes.

ASI-Volcanic Risk System (SRV): A pilot project to develop EO data processing modules and products for volcanic activity monitoring, first results

The ASI-SRV (Sistema Rischio Vulcanico) project is devoted to the development of an integrated system based on EO and Non EO data to respond to specific needs of the Italian Civil Protection Department (DPC). ASI-SRV provides the capability to import many different EO and Non EO data into the system, it maintains a repository where the acquired data have to be stored and generates selected products which will be functional to the different volcanic activity phases. The processing modules for Radar and EO Optical sensors data allow to estimate a number of parameters which include: surface thermal proprieties, gas, aerosol and ash emissions and to characterize the volcanic products in terms of composition and geometry, surface deformations in terms of displacements and velocity. All the generated products are related to Italian actives volcanoes and three test sites have been chosen to demonstrate the capability of this integrated system: Vesuvio, Campi Flegrei (Campania region) and Etna (Sicilia region). In this paper the first results obtained by means of modules developed within the ASI-SRV project and dedicated to the processing of EO historical series are presented.

2012 hyperspectral airborne campaign on Etna: Multi data acquisition for ASI-PRISMA project

In the frame of the Italian Space Agency (ASI) Hyperspectral Space Mission PRISMA, the Istituto Nazionale di Geofisica e Vulcanologia coordinates the scientific project ASI-AGI aimed to develop specific algorithms and products for geophysical applications. Data validation and calibration activities have been focused on active volcanic areas and three test sites have been selected in Sicily, Italy. In the period 23-27 June 2012 the project team has organized an hyperspectral airborne and field measurements campaign over Mt. Etna, Paternò area and Ciclopi Islands investigating various surface targets using different instruments. The airborne and ground campaign have been planned during satellites passes of Hyperion and ASTER. The whole data set acquired during this campaign allowed the airborne data calibration and provide a suitable data set to simulate PRISMA data and to test the developed algorithms in the framework of the project.

Generation of Added Values Products Supporting Risk Analysis

Active volcanoes are spread all over the world and are located in specific areas correlated to geologic structures. In the last 10,000 years more than 1300 volcanoes have erupted, but only half of the eruptions have been reported in historical texts. It has been estimated that every year 50 volcanic eruption may occur threating about 10 % of the worldwide population. Considering the constant increase in human population and that many major cities are placed in the proximity of active volcanoes, the number of people subjected to the risks caused by volcanic eruptions is also increasing. Stated the problem dimension, it shall be defined the method to counter act the crisis scenario. A volcanic eruption can be faced under different point of view, on one side it can be deeply studied in order to improve the knowledge of geophysical mechanism which drives the eruption itself, on the other hand it is important to set up a service based on the integration of different dataset and aimed to deliver added values products toward whose are in charge to manage the risk associated. One response to last sentence is the Sistema Rischio Vulcanico (ASI-SRV) project funded by the Italian Space Agency (ASI) in the frame of the National Space Plan 2003-2005 under the Earth Observations section for natural risks management. The ASI-SRV Project is coordinated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) which is responsible, in Iyaly, at national level for the volcanic monitoring. The main goal of the ASISRV project is to define, develop and demonstrate tools and products, based on the integration Earth Observation data (EO) with data coming from the ground monitoring network developed at national and local level, to support the risk management decision procedures. The project philosophy is to implement, by incremental versions, specific modules which allow to process, store and visualize through a dedicated Web-GIS tools, added value information derived by EO and No EO data.

Development of a tool using satellite products for volcanic eruption monitoring

The availability of EO satellites in the last decades has offered the possibility to integrate the ground surveillance with satellite derived information increasing the knowledge of territory situation and phenomena characteristics during natural disasters. All member states of the European Union are affected by at least one major natural hazard such as Floods, Fires, Windstorms, Earthquakes, Volcanoes, Landslides, Rapid vertical ground displacements, and also by risks related to man-made activities such as chemical and nuclear accidents. The above mentioned risks can be mitigated through a better prevention and preparedness within a multi-risk joint effort of all actors in risk management and integration of societal needs. In this frame the EC FP6 Preview-Eurorisk project aims at developing new geo-information services for atmospheric, geophysical and man-made risk management at a European level; the End-Users of these services are represented by the Civil Defence Agencies of the different partner countries. In the Geophysical Cluster dedicated to earthquakes and volcanoes risks, a prototype system to support end-users (i.e. national Civil Protections) has been developed. The service separates the natural phenomena in 3 main phases: earlywarning, crisis management and post-crisis. The service prototype provides easy and rapid access to assets mapping, mapping, monitoring, forecasting and awareness of risk as well as damage assessment at European, regional and local levels according to the operative necessities of the End-Users. The system products chain consists in: inquiring the satellite data archives, extracting the information/parameter from Earth Observation data using already developed scientific modules producing numerical values or geo-coded thematic maps as products archived in the database system. The End-User interface consists in a Web-GIS system where products, in vector or raster format, are visualized and distributed according to the specific emergency phase.

ASI-SRV optical sensor data processing modules

The Project called Sistema Rischio Vulcanico (SRV) is funded by the Italian Space Agency (ASI) in the frame of the National Space Plan 2003-2005 under the Earth Observations section for natural risks management. The SRV Project is coordinated by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) which is responsible at national level for the volcanic monitoring. The main goal of the SRV project is to define, develop and demonstrate tools and products, based on the EO data, to support the risk management decision procedures. This is achieved through the development of data processing modules dedicated to the generation of specific products and to the dissemination of the information to the end-users in a form suitable for decision making. An important step of the project development regards the technical and scientific feasibility of the provided products.