Flavio Cannavò
Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, Department Member
- Time series analysis, Nonlinear Time Series, Ground deformation of active volanoes by GPS observations., Tectonic Lipari-Vulcano complex, Remote Sensing, Support Vector Machines, and 20 moreMachine Learning, Seismology, Geophysics, Earth Sciences, Linear Regression, Multi Class Classification, Artificial Intelligence, Climate Change, Signal Processing, Forecasting, Nonlinear dynamics, Time Series, Forecasting and Prediction Tools, Time-Series Analysis, Chaos, Non Linear Dynamics, Non-Linear Dynamics, Bifurcation, Stability and Chaos, and Predictabilityedit
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The most continuous and ubiquitous seismic signal on Earth is the microseism, closely related to ocean wave energy coupling with the solid Earth. A peculiar feature of microseism recorded in Antarctica is the link with the sea ice, making... more
The most continuous and ubiquitous seismic signal on Earth is the microseism, closely related to ocean wave energy coupling with the solid Earth. A peculiar feature of microseism recorded in Antarctica is the link with the sea ice, making the temporal pattern of microseism amplitudes different with respect to the microseism recorded in low-middle latitude regions. Indeed, during austral winters, in Antarctica the oceanic waves cannot efficiently excite seismic energy because of the sea ice in the Southern Ocean. Here, we quantitatively investigate the relationship between microseism, recorded along the Antarctic coasts, and sea ice concentration. In particular, we show a decrease in sea ice sensitivity of microseism, due to the increasing distance from the station recording the seismic signal. The influence seems to strongly reduce for distances above 1,000 km. Finally, we present an algorithm, based on machine learning techniques, allowing to spatially and temporally reconstruct th...
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This is deliverable D3.1 – Database Structure – of the H2020 FET-Open project NEWTON-g (GA No 801221). This document was produced in the framework of WP3 (On-field application).<br> The aim of this document is to present our... more
This is deliverable D3.1 – Database Structure – of the H2020 FET-Open project NEWTON-g (GA No 801221). This document was produced in the framework of WP3 (On-field application).<br> The aim of this document is to present our strategy for storing and sharing NEWTON-g data, in compliance with the FAIR guiding principles.
Structure and dynamics of fault systems can be investigated using repeating earthquakes as repeatable seismic sources, alongside ground deformation measurements. Here we utilise a dataset of repeating earthquakes which occurred between... more
Structure and dynamics of fault systems can be investigated using repeating earthquakes as repeatable seismic sources, alongside ground deformation measurements. Here we utilise a dataset of repeating earthquakes which occurred between 2000 and 2019 along the transtensive Pernicana fault system on the northeast flank of Mount Etna, Italy, to investigate the fault structure, as well as the triggering mechanisms of the seismicity. By grouping the repeating earthquakes into families and integrating the seismic data with GPS measurements of ground deformation, we identify four distinct portions of the fault. Each portion shows a different behaviour in terms of seismicity, repeating earthquakes and ground deformation, which we attribute to structural differences including a segmentation of the fault plane at depth. The recurrence intervals of repeating earthquake families display a low degree of regularity which suggests an episodic triggering mechanism, such as magma intrusion, rather t...
Research Interests: Geology and Seismology
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Volcanology, seismology and Earth Sciences in general, like all quantitative sciences, are increasingly dependent on the quantity and quality of data acquired [...]
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The detection of volcanic plumes produced during explosive eruptions is important to improve our understanding on dispersal processes and reduce risks to aviation operations. The ability of Global Position-ing System (GPS) to retrieve... more
The detection of volcanic plumes produced during explosive eruptions is important to improve our understanding on dispersal processes and reduce risks to aviation operations. The ability of Global Position-ing System (GPS) to retrieve volcanic plumes is one of the new challenges of the last years in volcanic plume detection. In this work, we analyze the Signal to Noise Ratio (SNR) data from 21 permanent stations of the GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, that are located on the Mt. Etna (Italy) flanks. Being one of the most explosive events since 2011, the eruption of November 23, 2013 was chosen as a test-case. Results show some variations in the SNR data that can be correlated with the presence of an ash-laden plume in the atmosphere. Benefits and limitations of the method are highlighted.
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Open conduit basaltic volcanoes can be potentially hazardous as the eruptive activity may turn suddenly from a steady state to highly explosive. Unexpected changes in explosion intensity are recurrent at Stromboli volcano, where major... more
Open conduit basaltic volcanoes can be potentially hazardous as the eruptive activity may turn suddenly from a steady state to highly explosive. Unexpected changes in explosion intensity are recurrent at Stromboli volcano, where major explosions and large-scale paroxysms sometimes break off the ordinary, Strombolian activity with little or no warning. Two powerful paroxysmal eruptions took place at Stromboli volcano during the summer 2019, causing widespread fires, consistent damages across the island, injuries and one fatality. Prediction of similar events is really challenging for the modern volcanology, though models propaedeutic to early-warning monitoring systems are not properly assessed yet in many volcanoes worldwide. Here, we present a multi-parametric study that combines petrological and geophysical data to investigate processes generating the two paroxysms. The time information derived by Li enrichments in plagioclase crystals correlates with tilt time series derived by s...
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Abstract Between February 6 and 12, 2016, an earthquake sequence affected the western sector of the Hyblean foreland domain in SE Sicily (Italy), a region characterized by several disastrous events, as the seismic history describes, of... more
Abstract Between February 6 and 12, 2016, an earthquake sequence affected the western sector of the Hyblean foreland domain in SE Sicily (Italy), a region characterized by several disastrous events, as the seismic history describes, of which little is still known about the seismogenic sources. Despite the low magnitude of most events (MLmax 4.3), the sequence represents one of the largest episodes of seismic strain release in the area over the last 30 years since the December 13, 1990 earthquake (ML = 5.4). Accurate seismic phase arrival times related to the seismic sequence were obtained by using a wave-correlation method which enabled a significant improvement in precision of earthquake locations, allowing to detect a N-S striking rupture area about 8 km deep. The N-S trending discontinuity well matches, in the near-surface, with the observed geological structures, in rather good agreement with the computed focal solutions which evidence a roughly N-S elongated structure characterized by a left-lateral kinematics. The detailed knowledge learned on the geometry of the fault surface activated by the seismic sequence, together with the characterization of earthquake source parameters, gave important constraints for a realistic estimation of seismic ground motion throughout stochastic simulations. The modeling technique was based on the comparison between instrumental signals of the strongest event of the sequence and the associated synthetic ones. This permitted to properly define the set of input parameters for the construction of a realistic scenario for a MW 6.1 earthquake, which provides the largest contribution to the seismic hazard for the investigated area.
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Global warming is making extreme wave events more intense and frequent. Hence, the importance of monitoring the sea state for marine risk assessment and mitigation is increasing day-by-day. In this work, we exploit the ubiquitous seismic... more
Global warming is making extreme wave events more intense and frequent. Hence, the importance of monitoring the sea state for marine risk assessment and mitigation is increasing day-by-day. In this work, we exploit the ubiquitous seismic noise generated by energy transfer from the ocean to the solid earth (called microseisms) to infer the sea wave height data provided by hindcast maps. To this aim, we use a combined approach based on statistical analysis and machine learning. In particular, a random forest model shows very promising results in the spatial and temporal reconstruction of sea wave height by microseisms. The observed dependence of input importance from the distance sea grid cell-seismic station suggests how the reliable monitoring of the sea state in a wide area by microseisms needs data recorded by dense networks, comprising stations evenly distributed along the coastlines.
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The Timpe Fault System is the source of very shallow but destructive earthquakes that affect several towns and villages on the eastern flank of Mt. Etna (Italy). In 1984, several seismic events, and specifically on October 25, caused one... more
The Timpe Fault System is the source of very shallow but destructive earthquakes that affect several towns and villages on the eastern flank of Mt. Etna (Italy). In 1984, several seismic events, and specifically on October 25, caused one fatality, 12 injuries and produced serious damage in the Zafferana and Acireale territories. This seismicity was mainly related to the activity of the Fiandaca Fault, one of the structures belonging to the Timpe Fault System.…
Research Interests: Geology and Seismology
Abstract This paper describes a visual processing technique for automatic frog (Xenopus Laevis sp.) localization and identification. The problem of frog identification is to process and classify an unknown frog image to determine the... more
Abstract This paper describes a visual processing technique for automatic frog (Xenopus Laevis sp.) localization and identification. The problem of frog identification is to process and classify an unknown frog image to determine the identity which is recorded previously on an image database. The frog skin pattern (ie texture) provides a unique feature for identification. Hence, the study investigates three different kind of features (ie Gabor filters, granulometry, threshold set compactness) to extract texture information. The classifier is built on nearest ...
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ABSTRACT [1] Since the second half of the 1990s, the eruptive activity of Mount Etna has provided evidence that both explosive and effusive eruptions display periodic variations in discharge and eruption style. In this work, a... more
ABSTRACT [1] Since the second half of the 1990s, the eruptive activity of Mount Etna has provided evidence that both explosive and effusive eruptions display periodic variations in discharge and eruption style. In this work, a multiparametric approach, consisting of comparing volcanological, geophysical, and geochemical data, was applied to explore the volcano&#39;s dynamics during 2009–2011. In particular, temporal and/or spatial variations of seismicity (volcano-tectonic earthquakes, volcanic tremor, and long-period and very long period events), ground deformation (GPS and tiltmeter data), and geochemistry (SO2 flux, CO2 flux, CO2/SO2 ratio) were studied to understand the volcanic activity, as well as to investigate magma movement in both deep and shallow portions of the plumbing system, feeding the 2011 eruptive period. After the volcano deflation, accompanying the onset of the 2008–2009 eruption, a new recharging phase began in August 2008. This new volcanic cycle evolved from an initial recharge phase of the intermediate-shallower plumbing system and inflation, followed by (i) accelerated displacement in the volcano&#39;s eastern flank since April 2009 and (ii) renewal of summit volcanic activity during the second half of 2010, culminating in 2011 in a cyclic eruptive behavior with 18 lava fountains from New Southeast Crater (NSEC). Furthermore, supported by the geochemical data, the inversion of ground deformation GPS data and the locations of the tremor sources are used here to constrain both the area and the depth range of magma degassing, allowing reconstructing the intermediate and shallow storage zones feeding the 2011 cyclic fountaining NSEC activity.
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The paucity of geodetic data acquired on active volcanoes can make the understanding of modelling magmatic systems quite difficult. In this study, we propose a novel approach, which allows improving the parameter estimation of analytical... more
The paucity of geodetic data acquired on active volcanoes can make the understanding of modelling magmatic systems quite difficult. In this study, we propose a novel approach, which allows improving the parameter estimation of analytical models of magmatic sources (e.g., shape, depth, dimensions, volume change, etc.) by means of a joint inversion of surface ground deformation data and P-axes of focal plane solutions. The methodology is first verified against a synthetic dataset of surface deformation and strain within the medium, and then applied to real data from an unrest episode occurred before the May 13 2008 eruption at Mt. Etna (Italy). The main results clearly indicate the joint inversion improves the accuracy of the estimated source parameters by about 70 %. The statistical tests indicate that the source depth is the parameter with the highest increment of accuracy. In addition, a sensitivity analysis confirms that displacements data are more useful to constrain the pressure and the horizontal location of the source than its depth, while the P-axes better constrain the depth estimation.
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We present an improved rendition of the geodetic velocity and strain fields in Sicily and southern Calabria obtained through the analysis of 18 years of GPS observations from continuous and survey station networks. The dense spatial... more
We present an improved rendition of the geodetic velocity and strain fields in Sicily and southern Calabria obtained through the analysis of 18 years of GPS observations from continuous and survey station networks. The dense spatial coverage of geodetic data provides precise quantitative estimates of previously established first-order active kinematic features, including: i) a narrow east-west-elongated belt of contraction (∼ 1–1.5 mm/yr) extending offshore northern Sicily from Ustica to Stromboli across the Aeolian Islands; ii) a ...
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Volcano observatories provide near real-time information and, ultimately, forecasts about volcano activity. For this reason, multiple physical and chemical parameters are continuously monitored. Here, we present a new method to... more
Volcano observatories provide near real-time information and, ultimately, forecasts about volcano activity. For this reason, multiple physical and chemical parameters are continuously monitored. Here, we present a new method to efficiently estimate the location and evolution of magmatic sources based on a stream of real-time surface deformation data, such as High-Rate GPS, and a free-geometry magmatic source model. The tool allows tracking inflation and deflation sources in time, providing estimates of where a volcano might erupt, which is important in understanding an on-going crisis. We show a successful simulated application to the pre-eruptive period of May 2008, at Mount Etna (Italy). The proposed methodology is able to track the fast dynamics of the magma migration by inverting the real-time data within seconds. This general method is suitable for integration in any volcano observatory. The method provides first order unsupervised and realistic estimates of the locations of ma...
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We present an improved evaluation of the current strain and stress fields in the Southern Apennines (Italy) obtained through a careful analysis of geodetic, seismological and borehole data. In particular, our analysis provides an updated... more
We present an improved evaluation of the current strain and stress fields in the Southern Apennines (Italy) obtained through a careful analysis of geodetic, seismological and borehole data. In particular, our analysis provides an updated comparison between the accrued strain recorded by geodetic data, and the strain released by seismic activity in a region hit by destructive historical earthquakes. To this end, we have used nine years of GPS observations (2001-2010) from a dense network of permanent stations, a data set of 73 well-constrained stress indicators (borehole breakouts and focal mechanisms of moderate-to-large earthquakes) and published estimations of the geological strain accommodated by active faults in the region. Although geodetic data are generally consistent with seismic and geological information, previously unknown features of the current deformation in southern Italy emerge from this analysis. The newly obtained GPS velocity field supports the well-established notion of a dominant NE-SW-oriented extension concentrated in a ˜50-km-wide belt along the topographic relief of the Apennines, as outlined by the distribution of seismogenic normal faults. Geodetic deformation is, however, non-uniform along the belt, with two patches of higher strain-rate and shear-stress accumulation in the north (Matese Mountains) and in the south (Irpinia area). Low geodetic strain-rates are found in the Bradano basin and Apulia plateau to the east. Along the Ionian Sea margin of southern Italy, in southern Apulia and eastern Basilicata and Calabria, geodetic velocities indicate NW-SE extension that is consistent with active shallow-crustal gravitational motion documented by geological studies. In the west, along the Tyrrhenian margin of the Campania region, the tectonic geodetic field is disturbed by volcanic processes. Comparison between the magnitude of the geodetic and the seismic strain rates (computed using a long historical seismicity catalogue) allow detecting areas of high correlation, particularly along the axis of the mountain chain, indicating that most of the geodetic strain is released by earthquakes. This relation does not hold for the instrumental seismic catalogue, as a consequence of the limited time span covered by instrumental data. In other areas (e.g. Murge plateau in central Apulia), where seismicity is very low or absent, the yet appreciable geodetic deformation might be accommodated in aseismic mode. Overall, the excellent match between the stress and the strain-rate directions in much of the Apennines indicates that both earthquakes and ground deformation patterns are driven by the same crustal forces.
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After a recharge phase begun in 2007, on May 13, 2008 a new eruption started on Mt. Etna volcano. The final intrusion was very fast, accompanied by a violent seismic swarm and marked ground deformation changes recorded at the permanent... more
After a recharge phase begun in 2007, on May 13, 2008 a new eruption started on Mt. Etna volcano. The final intrusion was very fast, accompanied by a violent seismic swarm and marked ground deformation changes recorded at the permanent tilt and GPS networks. The frame of the eruptive event and the associated phenomena (earthquakes, deformation, lava emission, fracture propagation) generated great concern and fears that the eruptive fractures might propagate dangerously downslope. We modelled the ground deformation pattern and inferred a double phase dike which explains both the mechanism of the vertical intrusion and also the attempt of the dike to propagate in the northern sector in its shallower part. We show that the 2008 intrusion was characterized by a mechanism which is new and different to the ones modelled in previous eruptions.
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On 1908 December 28 a Mw=7.1 earthquake struggled the cities of Messina and Reggio Calabria causing more than 100.000 casualties. Since that dramatic episode, geologists and geophysicists have attempted to understand the complex tectonic... more
On 1908 December 28 a Mw=7.1 earthquake struggled the cities of Messina and Reggio Calabria causing more than 100.000 casualties. Since that dramatic episode, geologists and geophysicists have attempted to understand the complex tectonic of the Calabro-Peloritan Arc, with the aim to improve the knowledge of the active faults of this area and the seismic hazard. In this work we have studied the deformation pattern along the southernmost part of the Calabro-Peloritan Arc through 12 years of GPS measurements. We present and discuss mayor results, in terms of rates of movements along the principal fault systems and of velocity field (computed in an Eurasian reference frame) and strain-rate field of the investigated area. In particular, we have found that a 0.15 μstrain/yr extension across the Messina Strait and across the Aeolian-Tindari-Letoianni fault system is acting. Moreover, an N-S compressive strain (0.65 μstrain/yr) is acting across Vulcano and Lipari Islands coupled with an extensional strain-rate of 0.15 μstrain/yr in E-W direction. The results are also investigated through a simplified analytical model of the local tectonic, taking into account the regional context at a larger scale (Eurasia-Africa convergence). The results inferred from the analytical inversion of geodetic velocities have been compared with structural and seismological data of the investigated area.
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After a recharge phase began in 2007, on 13 May 2008, a new eruption started at Mt. Etna volcano. The first hours of the eruption onset were accompanied by a strong seismicity (more than 230 seismic events located beneath the... more
After a recharge phase began in 2007, on 13 May 2008, a new eruption started at Mt. Etna volcano. The first hours of the eruption onset were accompanied by a strong seismicity (more than 230 seismic events located beneath the north-eastern summit area) the opening of some eruptive fracture systems and a few tens of centimetres of horizontal displacement at the GPS stations close to the summit area. All these features strongly depend by the local stress field within the volcano. In order to investigate these aspects, we deeply investigated the local stress field accompanying the 2008 Mt. Etna eruption onset, through the integration of GPS observation and seismological data. In particular, in a first step, we adopted a least square approach and, taking into account the network geometry and the deformation observed at each GPS site, we estimated the horizontal strain field. Then, assuming an isotropic and linear-elastic state, the horizontal stress was computed as stress orientations and stress magnitudes, through the Hooke’s law. A formal inversion of focal mechanisms computed for earthquakes occurred during the first days of the eruption, allowed us to obtain the 3D orientation of the three principal stress axes plus the stress ratio of the stress magnitudes. Main results will be discussed within the tectonic framework of the summit area of Mt. Etna, also considering structural data and mechanical constraints.
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Nowadays continuous GPS time series are considered a crucial product of GPS permanent networks, useful in many geo-science fields, such as active tectonics, seismology, crustal deformation and volcano monitoring (Altamimi et al. 2002,... more
Nowadays continuous GPS time series are considered a crucial product of GPS permanent networks, useful in many geo-science fields, such as active tectonics, seismology, crustal deformation and volcano monitoring (Altamimi et al. 2002, Elósegui et al. 2006, Aloisi et al. 2009). Although the GPS data elaboration software has increased in reliability, the time series are still affected by different kind of noise, from the intrinsic noise (e.g. thropospheric delay) to the un-modeled noise (e.g. cycle slips, satellite faults, parameters changing). Typically GPS Time Series present characteristic noise that is a linear combination of white noise and correlated colored noise, and this characteristic is fractal in the sense that is evident for every considered time scale or sampling rate. The un-modeled noise sources result in spikes, outliers and steps. These kind of errors can appreciably influence the estimation of velocities of the monitored sites. The outlier detection in generic time series is a widely treated problem in literature (Wei, 2005), while is not fully developed for the specific kind of GPS series. We propose a robust automatic procedure for cleaning the GPS time series from the outliers and, especially for long daily series, steps due to strong seismic or volcanic events or merely instrumentation changing such as antenna and receiver upgrades. The procedure is basically divided in two steps: a first step for the colored noise reduction and a second step for outlier detection through adaptive series segmentation. Both algorithms present novel ideas and are nearly unsupervised. In particular, we propose an algorithm to estimate an autoregressive model for colored noise in GPS time series in order to subtract the effect of non Gaussian noise on the series. This step is useful for the subsequent step (i.e. adaptive segmentation) which requires the hypothesis of Gaussian noise. The proposed algorithms are tested in a benchmark case study and the results confirm that the algorithms are effective and reasonable. Bibliography - Aloisi M., A. Bonaccorso, F. Cannavò, S. Gambino, M. Mattia, G. Puglisi, E. Boschi, A new dyke intrusion style for the Mount Etna May 2008 eruption modelled through continuous tilt and GPS data, Terra Nova, Volume 21 Issue 4 , Pages 316 - 321, doi: 10.1111/j.1365-3121.2009.00889.x (August 2009) - Altamimi Z., Sillard P., Boucher C., ITRF2000: A new release of the International Terrestrial Reference frame for earth science applications, J Geophys Res-Solid Earth, 107 (B10): art. no.-2214, (Oct 2002) - Elósegui, P., J. L. Davis, D. Oberlander, R. Baena, and G. Ekström , Accuracy of high-rate GPS for seismology, Geophys. Res. Lett., 33, L11308, doi:10.1029/2006GL026065 (2006) - Wei W. S., Time Series Analysis: Univariate and Multivariate Methods, Addison Wesley (2 edition), ISBN-10: 0321322169 (July, 2005)
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In these last years, an increasing interest in high rate GPS is clearly showed by the numbers of papers where this methodology is applied in seismology (Larson et al., 2003; Bock and Prawirodirdjo, 2004; Ji et al., 2004; Miyazaki et al.,... more
In these last years, an increasing interest in high rate GPS is clearly showed by the numbers of papers where this methodology is applied in seismology (Larson et al., 2003; Bock and Prawirodirdjo, 2004; Ji et al., 2004; Miyazaki et al., 2004; Elosegui et al., 2006.), in volcanology (Mattia et al., 2004), and in tsunami hazard evaluation (Blewitt et al., 2006). Sometime this technique is applied in "a posteriori", meaning that the data collected by the GPS stations are reprocessed and analysed, but the great potential of HRGPS is surely related to its application in the field of real time processing and to the big interest of the civil protection authorities in following dynamic processes related, for example, to the opening of a fracture field or to a dome extrusion during a volcanic eruption. Since 2002, the INGV (Istituto Nazionale di Geofisica e Vulcanologia) section of Catania (Italy) manage two real time high rate GPS networks in Stromboli and Etna volcanoes. In order to improve our capability to evaluate the volcanic risk and our knowledge of the deformative processes linked to magma movements at shallow depths, we developed a software tool finalised to the analysis of HRGPS data. This software tool, named iGeoPS©, runs in Matlab© framework and permits to analyze long series of HRGPS data sampled with any frequency. In particular, the tool can visualize raw data, statistically filter the raw data, sidereally filter the data, calculate power spectrum for specified windows (both in time and frequency content), display spectrograms of the signal, calculate statistics and RMS of the scatter of the data, and perform cross-correlation and trend analysis for different series. Moreover, iGeoPS© allows to do advanced non linear analysis such as fractal and chaotic analysis and integrates different non linear modelling techniques such as neural networks, fuzzy systems and wavelets. In this paper, after a brief introduction to the features of the developed tool, we summarize the main results related to the characteristics of the HRGPS signal and to the main volcanic events observed using this approach. Furthermore we show an analysis of data collected since 2003 on Mt.Etna where phenomena related to explosive activity, opening of fractures, tidal effects etc, clearly define the potential of this technique in volcano monitoring.
The unrest of Stromboli volcano leading to the February 27-April 2, 2007 eruptive period and the March 15 paroxysm is constrained by combining broadband seismic data and 1-Hz GPS (High Rate GPS - hereinafter HRGPS) measurements. During... more
The unrest of Stromboli volcano leading to the February 27-April 2, 2007 eruptive period and the March 15 paroxysm is constrained by combining broadband seismic data and 1-Hz GPS (High Rate GPS - hereinafter HRGPS) measurements. During the preeruptive stage, the simultaneous examination of seismic and HRGPS data, together with weather parameters, suggests the possible influence of external perturbations on the magmatic system, which evolved toward a critical state after January 2007. At the beginning of the eruption striking variations of the waveform and spectral content of very long period (VLP) events were observed. Moreover, some days after the onset of the eruption, a sudden change of the seismic and eruptive behaviour was recognized, while ground deformation began to show a deflation. The March 15 paroxysm was preceded, some days before, by a peak of the HRGPS spectral power densities (a small inflation) and by the variation of location and features of long period (LP) events together with the occurrence of a few VT earthquakes located at depths down to 3.5 km b.s.l.. These findings constrain, for the first time at Stromboli volcano, the deep origin of a fast rising magma batch, rich in gas, that led to a strong explosive event, and highlight a strict relationship between VLP seismicity and the eruptive activity.
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We have used continuously recording GPS and survey-mode GPS observations to determine a new velocity field of Southern Italy for the period 1996-2009. We have combined local, regional and global networks into a common reference frame... more
We have used continuously recording GPS and survey-mode GPS observations to determine a new velocity field of Southern Italy for the period 1996-2009. We have combined local, regional and global networks into a common reference frame (ITRF2005) and then rotated the estimated velocities with respect to both an Eurasian fixed and African fixed frame. Then, we have provided strain-rate values for the Eastern Sicily, where the GPS network is denser. The results highlight a different kinematic for the Calabrian Arc and Sicily. The Calabrian Arc behaves as an independent block. It has an independent motion with respect to both Eurasia and Africa. In Sicily the analysis of the geodetic velocities and strain-rate parameters shows the presence of different domains with different motions and deformation styles, besides local effects produced by the principal fault systems or volcanic activity. The deformation pattern can be considered as the result of the interaction between the main NNW-SSE regional compression and the local movements of the main faults cutting the area. The convergence along the Plio-Pleistocene nappe thrust front north of the Hyblean Plateau is active, with compressive strain-rate values of about 0.14 μstrain/yr. Part of the regional compression is localized in the Eastern sector of the Aeolian Islands, bounded at west by the Lipari-Vulcano complex, where the compressive strain-rate reaches the maximum values of about 0.65 μstrain/yr (with the principal axes mostly NW-SE oriented). A transition to extensional domains is observed in the Nebrodi-Peloritani and the Messina Straits area, showing the maximum strain-rate values along the Aeolian-Tindari-Letojanni and the Messina Straits fault systems. We have also calculated the movement rates along these fault systems.
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The NE flank of Stromboli volcano referred to as Sciara del Fuoco (SdF), due to its slope instability and the strombolian type activity is subject to landslides. Analysis performed on ground displacements measured at the SdF by an... more
The NE flank of Stromboli volcano referred to as Sciara del Fuoco (SdF), due to its slope instability and the strombolian type activity is subject to landslides. Analysis performed on ground displacements measured at the SdF by an automatic monitoring system referred to as THEODOROS (THEOdolite and Distancemeter Robot Observatory of Stromboli), have shown that the recorded cumulative probability of displacements are power-law distributed. The volcano flank seems affected by movements that could be explained using a mechanical model. The proposed model consists of a slider mass driven-noise placed on an inclined plane with the same incline angle of the SdF (θ=36.8°). The aim of our study is to investigate the effects of noise on the cumulative size distribution of the proposed model. In particular we show that appropriately choosing the range of variation for the intensity of a Gaussian distributed noise source with zero mean it is possible to model the observed displacements. This is an example of noise-induced critical phenomena.
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The unrest of Stromboli volcano leading to the February 27-April 2, 2007 eruptive period and the March 15 paroxysm is constrained by combining broadband seismic data and 1-Hz GPS (High Rate GPS - hereinafter HRGPS) measurements. During... more
The unrest of Stromboli volcano leading to the February 27-April 2, 2007 eruptive period and the March 15 paroxysm is constrained by combining broadband seismic data and 1-Hz GPS (High Rate GPS - hereinafter HRGPS) measurements. During the preeruptive stage, the simultaneous examination of seismic and HRGPS data, together with weather parameters, suggests the possible influence of external perturbations on the magmatic system, which evolved toward a critical state after January 2007. For this aim, we show that the cross wavelet transform and wavelet coherogram are very effective tools to study prospective coupling between heterogeneous time series. Some days after the onset of the eruption, a sudden change of the seismic and eruptive behaviour was recognized, while ground deformation began to show a deflation. The March 15 paroxysm was preceded, some days before, by a peak of the HRGPS spectral power densities (a small inflation) and by the variation of location and features of long period (LP) events together with the occurrence of a few VT earthquakes located at depths down to 3.5 km b.s.l. These findings constrain, for the first time at Stromboli volcano, the deep origin of a fast rising magma batch, rich in gas, that led to a strong explosive event, and highlight a strict relationship between VLP seismicity and the eruptive activity.
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We present an improved evaluation of the current strain and stress fields in the Southern Apennines (Italy) obtained through a careful analysis of geodetic, seismological and borehole data. In particular, our analysis provides an updated... more
We present an improved evaluation of the current strain and stress fields in the Southern Apennines (Italy) obtained through a careful analysis of geodetic, seismological and borehole data. In particular, our analysis provides an updated comparison between the accrued strain recorded by geodetic data, and the strain released by seismic activity in a region hit by destructive historical earthquakes. To this end, we have used nine years of GPS observations (2001-2010) from a dense network of permanent stations, a data set of 73 well-constrained stress indicators (borehole breakouts and focal mechanisms of moderate-to-large earthquakes) and published estimations of the geological strain accommodated by active faults in the region. Although geodetic data are generally consistent with seismic and geological information, previously unknown features of the current deformation in southern Italy emerge from this analysis. The newly obtained GPS velocity field supports the well-established notion of a dominant NE-SW-oriented extension concentrated in a ˜50-km-wide belt along the topographic relief of the Apennines, as outlined by the distribution of seismogenic normal faults. Geodetic deformation is, however, non-uniform along the belt, with two patches of higher strain-rate and shear-stress accumulation in the north (Matese Mountains) and in the south (Irpinia area). Low geodetic strain-rates are found in the Bradano basin and Apulia plateau to the east. Along the Ionian Sea margin of southern Italy, in southern Apulia and eastern Basilicata and Calabria, geodetic velocities indicate NW-SE extension that is consistent with active shallow-crustal gravitational motion documented by geological studies. In the west, along the Tyrrhenian margin of the Campania region, the tectonic geodetic field is disturbed by volcanic processes. Comparison between the magnitude of the geodetic and the seismic strain rates (computed using a long historical seismicity catalogue) allow detecting areas of high correlation, particularly along the axis of the mountain chain, indicating that most of the geodetic strain is released by earthquakes. This relation does not hold for the instrumental seismic catalogue, as a consequence of the limited time span covered by instrumental data. In other areas (e.g. Murge plateau in central Apulia), where seismicity is very low or absent, the yet appreciable geodetic deformation might be accommodated in aseismic mode. Overall, the excellent match between the stress and the strain-rate directions in much of the Apennines indicates that both earthquakes and ground deformation patterns are driven by the same crustal forces.
Research Interests:
On April 6, 2009 an Mw 6.3 earthquake occurred in the Abruzzo region (Italy) with epicentre located near the ancient town of L’Aquila. A few months before the main shock, the area S-W of L’Aquila experienced several foreshocks (about 60... more
On April 6, 2009 an Mw 6.3 earthquake occurred in the Abruzzo region (Italy) with epicentre located near the ancient town of L’Aquila. A few months before the main shock, the area S-W of L’Aquila experienced several foreshocks (about 60 events >M 2.0 since mid-January 2009), culminated in a seismic burst triggered by a M 4.1 event on the 30th of March. This sequence convinced us to install a few GPS receivers on pre-existing geodetic markers near the epicentres area (CaGeoNet markers), with the purpose to observe the high frequency component of the seismic events. In a few days two receivers were setup acquiring data at 10Hz and a few other permanent sites were switched to 1 Hz acquisition rate (RING network). On the 6th of April there were about 30 observing sites (RING and other regional real time GPS receivers) available in central Italy, 4 of them in the proximity of the main fault, observing the main shock event. To process the high rate data we setup different approaches using four different software packages (Bernese, Track, Geodetics' RTD, and Gipsy) and compare the post-processed kinematic solutions of the main shock event. Different approaches have been implemented to estimate the position at 1 and 10 Hz rate (differencing with reference stations, precise point positioning, epoch-by-epoch), all methods proved to be able to reproduce the observed deformation at sub-centimetre level. We investigate the effect of time and space-wise filters (sidereal and common mode filters) and discuss the differences of the solutions in terms of repeatability and their spectral content. We further evaluate the obtained instantaneous coseismic displacement field of the available permanent sites in the area in order to assess the role of possible after-slip processes.
Research Interests:
We present an improved rendition of the geodetic velocity and strain fields in Sicily and southern Calabria obtained through the analysis of 18 years of GPS observations from continuous and survey station networks.
Il monitoraggio sistematico delle variazioni dell'inclinazione del suolo, viene effettuato sui vulcani siciliani dall'INGV-CT, utilizzando differenti tipi di sensori ad alta precisione capaci di rilevare inclinazioni del suolo fino a 10-8... more
Il monitoraggio sistematico delle variazioni dell'inclinazione del suolo, viene effettuato sui vulcani siciliani dall'INGV-CT, utilizzando differenti tipi di sensori ad alta precisione capaci di rilevare inclinazioni del suolo fino a 10-8 radianti (Bonaccorso ed al., 2004). Le misure di tilt in continuo sui vulcani rappresentano un metodo rapido per l'individuazione di precursori di un'eruzione ed uno strumento di studio del comportamento dei vulcani stessi nelle fasi pre e post-eruttive.
In this paper we present the main results inferred from GPS data collected between 1998.00 and 2009.78 along the northern rim of the Hyblean Plateau from 9 continuous and 23 survey-mode sites.