Ecología, belleza y el camino hacia la gracia de la interrelación
Rodríguez, J.M. 2011. Ecología, belleza y el camino hacia la gracia de la interrelación. Prensa Libre, jueves 17 de febrero, p. 16 Opinión.
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Download (.pdf) Tephra architecture, pyroclast texture and magma rheology of mafic, ash-dominated eruptions: the Violent Strombolian phase of the Pleistocene Croscat (NE Spain) eruption.
C. Cimarelli, F. Di Traglia, A, Vona, and J. Taddeucci
Tephro- and chemo-stratigraphy of the Vulcanello Peninsula (Vulcano, Aeolian Islands)
New stratigraphic studies of the Vulcanello Peninsula have been used to better define the small-scale evolution of... more New stratigraphic studies of the Vulcanello Peninsula have been used to better define the small-scale evolution of this young (1000 AD and 325±100 BP) volcanic center and to re-investigate the last 1000 years of volcanic history for the Island of Vulcano (Aeolian Islands, Southern Italy). Vulcanello Peninsula is the northern-most part of the Island of Vulcano. It comprises a shoshonitic lava platform and a volcanic edifice made up of three overlying cones, which are shoshonitic to trachytic in composition. Volcanic activity in this area was coeval with the recent eruptions of the La Fossa Cone, the present-day active center of the island. Our goal is to constrain the recent volcanic development of this mafic volcano and to focus on the historic eruptive activity of the two other recent or active centres in the southern Aeolian Islands, Mt. Pilato (Island of Lipari) and La Fossa Cone. In order to do so, we reconstructed the stratigraphical setting of the proximal deposits of the three Vulcanello cones, through the investigation of 25 outcrops. We analyzed the stratigraphy of the tephra blankets deposited on the lava platform, studying 10 trenches. Our intention is to integrate morphological, textural and chemical data in order to correlate these deposits with the Vulcanello, La Fossa Cone or Mt Pilato. LA-MC-ICPMS (RHUL) analysis of juvenile clasts is underway in order to investigate the evolution of the Vulcanello juvenile clasts. In addition 14C dating is planned on selected organic matter from the volcanostratigraphic sections. Our preliminary data for the Vulcanello proximal deposits suggest that each of the three cones experienced several eruptions, with a wide spectrum of eruptive styles and a diversity of chemistry. The oldest cone (Vulcanello I) is characterised by four different eruptions separated by minor unconformities or reworking material indicative of little or not time breaks in the eruptive cycle. The eruptions shift from Violent Strombolian to Hawaiian in style, testifying to a reduction in fragmentation and dispersal. The second cone (Vulcanello II), contains volcanic deposits from Strombolian eruptions only. The third cone (Vulcanello III), displays a complex evolution with an initial effusive episode of a trachytic lava flow, followed by phreatic explosions, evident as altered fine ash layers. These deposits are interbedded with scoriaceous fall deposits, attesting the occurrence of some mild explosive activity during this eruptive phase. This detailed study of the effusive and explosive products from Vulcanello reveals rapid evolution of Vulcanello during the initial phases (1000 AD to 1200 AD) with voluminous mafic eruptions, both effusive and explosive. A progressive reduction in emitted volume is apparent. The presence of abundant explosive deposits related to phreatic explosions during the Vulcanello III phase, is related to the presence of water, a reduction in magma volume and the presence of intense hydrothermal activity in the latter stage of the evolution of Vulcanello evolution until 1878. This may indicate the presence of a stable shallow thermal anomaly.
Understanding conduit dynamics and forecasting major strombolian explosions by groundbased radar interferometry
Federico DI TRAGLIA, Chiara DEL VENTISETTE, Mauro ROSI, Francesco MUGNAI, Emanuele INTRIERI, Sandro MORETTI, Nicola CASAGLI
Landslide impacts on Agrigento’s Cathedral imaged with radar interferometry
Francesca Cigna, Vincenzo Liguori, Chiara Del Ventisette, Nicola Casagli
ERS1/2 (1992-2000), ENVISAT (2002-2008) and
RADARSAT1 (2003-2007) satellite data, processed with
Persistent... more
ERS1/2 (1992-2000), ENVISAT (2002-2008) and
RADARSAT1 (2003-2007) satellite data, processed with
Persistent Scatterer Interferometry, are exploited to study
the historic urban area of Agrigento, Italy, whose
structural stability is threatened by retrogressive
landslide processes. Up to 2-5 mm/yr of line-of-sight
displacement are observed in 1992-2008 on the staircase
and the left aisle of the Cathedral. Displacement
acceleration to 13-15 mm/yr is measured in July 2006 -
May 2007, in the northern portion of the churchyard, in
front of the left aisle. The areas moving at higher rates,
located at the edge of the NW slope of Girgenti hill,
correspond to those showing major structural damages.
Aggravation of structural instability of the Cathedral and
increased risk of collapses is observed in 2011.
Monitoring of ground displacements and identification of trend deviations during post-processing of satellite InSAR time series
Francesca Cigna, Chiara Del Ventisette, and Nicola Casagli
Using a Ground Based radar interferometer during emergency: the case of A3 motorway (Salerno Reggio-Calabria) treated by landslide
Chiara Del Ventisette, Emanuele Intrieri, Guido Luzi, and Nicola Casagli
The costal landslide from analogue experiments: perspectives and limitation
Chiara Del Ventisette, Teresa Nolesini, Sandro Moretti, Riccardo Fanti
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Landslide detection and long-term monitoring in urban area by means of advanced interferometric techniques
Francesca Cigna, Chiara Del Ventisette, Vincenzo Liguori, and Nicola Casagli
INSAR TIME-SERIES ANALYSIS FOR MANAGEMENT AND MITIGATION OF HYDROGEOLOGICAL RISK IN URBAN AREA
CIGNA F. , DEL VENTISETTE C. , LIGUORI V. , CASAGLI N.
Spaceborne SAR analysis for landslides mapping in the framework of the PREVIEW project
Gaia Righini (University of Firenze, Italy) ・ Chiara Del Ventisette (University of Firenze, Italy) ・ Mario Costantini (Telespazio, Italy) ・ Fabio Malvarosa (Telespazio, Italy) ・ Federico Minati (Telespazio, Italy)
Landslide inventory mapping by SAR interferometry is here described. Data from ERS and Envisat
satellites, with... more
Landslide inventory mapping by SAR interferometry is here described. Data from ERS and Envisat
satellites, with temporal range from 1995 to 2008, were used
to updated a landslide inventory map mainly concerning state
of activity and geometry. A test site was chosen in Lombardia
region (Italy) in the framework of the PREVIEW EU-GMES
FP6 project. Results gave evidence that SAR interferometry is
a powerful tool for landslides mapping due to its capability to
measure ground displacements with millimetric accuracy.
Case study on the updating of landslide inventory map with remote sensing data
G. Righini, C. Del Ventisette, N. Casagli and L. Lombardi
Ground-based InSAR Monitoring of an Active Volcano and Related Landslides
Nicola Casagli (Florence University, Italy) ・ Filippo Catani (Florence University, Italy) ・ Chiara Del Ventisette (Florence University, Italy) ・ Letizia Guerri (Florence University, Italy) ・ Dario Tarchi (European Commission, Italy) ・ Joaquim Fortuny (European Commission, Italy) ・ Giuseppe Antonello (European Commission, Italy) ・Davide Leva (Ellegi-LiSALab s.r.l., Italy) ・ Carlo Rivolta (Ellegi-LiSALab s.r.l., Italy)
Stromboli volcano (Italy) is characterized by a typical
“Strombolian activity” which consists of very low... more
Stromboli volcano (Italy) is characterized by a typical
“Strombolian activity” which consists of very low energy
explosions, every 10-15 minutes. In December 2002 an
eruption caused a landslide on the NW slope of the volcano
(Sciara del Fuoco slope, SdF) and produced a tsunami.
Concerns over the possibility of further slope collapses of the
SdF led to the set up of a permanent monitoring system of
ground deformations.
The ground-based radar interferometer (GB-InSAR)
system installed on the Stromboli Island (Fig. 1) was
designed by the Joint Research Centre of the European
Commission (Rudolf & Tarchi, 1999; Antonello et al., 2004);
it is continuously active since 20 February 2003 (Antonello et
al., 2003; Casagli et al., 2003 Casagli et a., 2004; Antonello et
al., 2007) and produces, on average, 120 images per day of
the area under investigation (NW flank of crater and the upper
part of the SdF), characterized by a resolution of about 2m ×
2m, with an accuracy of the measurement of less than 1 mm.
Interferograms (obtained using pairs of averaged
sequential images) contain the displacement vector along the
line-of-sight (LoS) in the time interval between two
acquisitions. Negative values of displacement indicate a
movement toward the sensor (shortening along the LoS). On
the crater area this direction of movement correspond to the
inflation of the volcanic cone while, on the SdF, this is
usually related to a local bulging or to the downslope sliding
of the volcano-clastic material accumulated on the SdF slope.
Conversely, a positive value of displacement identifies a
movement backward with respect to the sensor (lengthening
along the LoS) that on the crater area could be related to the
deflation of the volcanic cone.
In January 2007, the GB-InSAR showed a progressive
acceleration of deformation on the NE crater. The recorded
velocity progressed from 0.04 mm/h to 0.7 mm/h toward the
radar that suggest an inflation of the upper sector of the
volcanic system. The increase in the deformation rate
successively involves the portion the SdF (15 February 2007)
in which the velocity increased from 0.02 mm/h to 0.25 mm/h,
toward the sensor.
These events are related to the new eruption occurred at
the end of February 2007. The effusive phase (from 27
February to 12 April) started with an explosion to the lower
part of the crater (causing a landslide on the portion of the
crater flank) and with the opening of the effusive vent at 600
m a.s.l. Velocities in the first hours of the eruption were so
high that exceeded the capability of the GB-InSAR device.
After few hours from the effusion onset, the
interferograms returned partly coherent and showed a
complex deformation pattern characterized by:
1. a complete decorrelation on the crater flank due to the
explosion and to morphological changes related to the crater
collapse;
2. concentric interferometric fringes related to the bulging
before the vent opening at 600 m a.s.l.;
3. parallel interferometric fringes related to landslide
movements on the SdF.
During the entire effusive phase, velocity values, on the
SdF slope, constantly decreased from 30 mm/h to 0.2 mm/h
toward the sensor, with the only exception of two limited
periods related to the opening of a new vent (8- 9 March) and
to a major explosion (15 March).
In particular since 8 March the velocity recorded on the
SdF increased again with movements toward the sensor. The
interferogram highlighted a very high deformation rate (more
than 300 mm/h, Fig. 2), which again exceeds the capability of
the correct phase unwrapping. The arrangement of the
interferometric fringes is related to the bulging due to the
opening of a new vent, occurred at 14.30 UT of 9 March.
Following the method proposed by Fukuzono (1985) and
Voight (1988) it has been possible to predict in advance of
one day the opening of the 9 March vent.
After 12 April, the eruption is to be considered concluded
and the velocity recorded by GB-InSAR progressively
decreased down to the values characteristic of the normal
activity of the Stromboli volcano.
The GB-InSAR monitoring allowed us to highlight
different deformation patterns, related to the eruption and to
the associated landslides, suggesting different triggering
mechanisms of the deformation process. Furthermore the
GB-InSAR system has recorded changes in the deformation
patterns, both on the crater area and on the SdF sector, in
advance with respect to the onset of each one of the relevant
events.
The absolute values of velocity recorded are plotted in Fig.
3: the light red line represents movements toward the sensor
(negative radar displacements), while the dark blue line
represents movement backward with respect to the sensor
(positive radar displacements). In Fig. 3 the three different
phases, above mentioned, are shown. The pre-effusive phase
(from 10 January to 27 February) is represented by the first
(light) shaded area, characterized by very low, progressively
increasing, deformation rates; the effusive phase (from 27
February to 12 April) by the second (dark) shaded area,
characterized by very high velocities of deformation and the
post-effusive phase (from 12 April) by the last area in which
the deformation rates decreased down to the pre-crisis values.
Ground-based interferometry for monitoring an active rockslide in the Italian Alps
N. Casagli, C. Del Ventisette, G. Mannucci, L. La Rocca, A. Ballini, G. Antonello, J. Fortuny-Guasch, D. Tarchi and D. Leva
THE VAIONT LANDSLIDE FROM ANALOGUE AND NUMERICAL EXPERIMENTS
M. Bonini, N. Casagli, G. Corti, C. Del Ventisette, G. Gigli, F. Sani, S. Santoro
Understanding the breaking mechanism of landslides is fundamental to evaluate their hazard and to
predict the... more
Understanding the breaking mechanism of landslides is fundamental to evaluate their hazard and to
predict the energy release during the principal failure phase, the associated velocity and the runout
distance. The intensity of the landslide represents one of the most important parameter to hypothesize the
hazard scenario.
The Vaiont Landslide represents one of the most disastrous Italian landslides in term of the human life
loss. Since the catastrophic failure, numerous works have addressed the causes of the failure and the
origin of the anomalous velocities, which have been estonated to be of the order of 25-30 m/s. We aimed
answering some of these questions, and we integrated the results of some analogue and numerical
models. The 2-D numerical approach has provided useful data to understand the triggering mechanism,
while the analogue models are 3D simulations that helped understanding the internal deformation pattern
developed into the sliding rock mass.
Microwave interferometric sensors as a tool for space and time analysis of active volcano deformations: the Stromboli case
Antonello, G. Fortuny, J. ; Tarchi, D. ; Casagli, N. ; Del Ventisette, C. ; Guerri, L. ; Luzi, G. ; Mugnai, F. ; Leva, D.
A Ground Based SAR Interferometer (GB-InSAR) was
installed at Stromboli volcano (Italy) in February 2003 to
installed at Stromboli volcano (Italy) in February 2003 to
continuously monitor the behaviour of the morphological
depression known as Sciara del Fuoco, SdF, with alerting
purposes. This was decided as a consequence of the collapse of a
large landslide from the NW slope of the SdF and the subsequent
tsunami occurred on December 2002. The GB-In SAR system,
working at Ku band, was set up on the stable right flank of the
SdF; it has been continuously working and during this last five
years has permitted to follow the temporal and spatial evolution
of the mass movement in the SdF and the crater. Interferometric
maps have permitted to assess the deformation field over a large
portion of the target area and to characterize different processes.
The system allowed to observe in particular two main events
occurred on 5 April 2003 (a major explosion) and on 27 February
2007 (beginning of the effusive phase) respectively. The potential
of the use of DInSAR from satellite platforms working at C band
to understand the dynamic of the whole volcano has been also
investigated. Different images acquired from the ERS2,
RADARSAT and ENVISAT satellites before and after the 2003
collapse of the landslide, and before and after the 2007 event,
have been interferometrically processed as well. Notwithstanding
the restricted number of available images, the ground
deformation occurred on the island due to the volcanic activity
has been obtained with spatial and temporal characteristics
complementary to those ones provided by GB-InSAR.
Salt diapirism during basin inversion: inferences from analogue modelling
CHIARA DEL VENTISETTE, DOMENICO MONTANARI, MARCO BONINI, FEDERICO SANI
The development of diapirs is generally correlated with
the activity of normal faults developed in extensional
the activity of normal faults developed in extensional
regime, which is considered the most efficient mechanism
triggering diapirism (e.g. JACKSON & VENDEVILLE, 1994).
The influence of contractional settings on diapir growth is
doubtless considered a less efficacious mechanism (or an
opposing mechanism to diapirism growth; e.g., VENDEVILLE,
1991). As far as we are concerned, in spite of numerous
works on analogue modelling exploring salt diapirism
mechanisms (i.e. COTTON & KOYI, 2000; COSTA & VENDEVILLE,
2001; SANS & KOYI, 2001; BONINI, 2003; BRUN &
FORT, 2004), analogue models have never explored the
influence of positive fault inversion on diapirism.
In this work we present the results of the modelling
built to understand the relationships between fault reactivation
and their orientation in respect to the maximum
horizontal stress axis (DEL VENTISETTE et alii, 2004). The
models is performed at the Tectonic Modelling Lab of the
CNR-IGG and of the Department of Earth Sciences of
Florence using a pure-shear/simple-shear deformational
apparatus.
Scaling of analogue models to the natural prototype
requires the geometrical, rheological, kinematical and
dynamical similarities to be satisfied (e.g., HUBBERT,
1937; RAMBERG, 1981; WEIJERMARS & SCHMELING, 1986;
WEIJERMARS et alii, 1993).
The models had initial dimensions of 45.5cm × 42cm
× 7cm and consisted of a pure brittle system representing
the crystalline basement of a natural prototype.
The models were extended at a constant velocity of 10
mm/h for seven hours up to the bulk extension (BE) of
about 16.5%. After 1 hour of deformation (approximately
2.3% BE), when the graben was 1 cm deep, a mixture of
silicone and oleic acid (Newtonian behaviour, ρ=1060 kg
m-3, η=103 Pa s) was placed into the graben to simulate
the ductile behaviour of salt layers that are generally
associated whit this geodynamic context. The successive
syn-tectonic sedimentation consisted of dry quartz sand
layers (Fontainebleau sand with grain dimension <250
mm) with different colours sieved at regular time intervals
(1 mm every 30 minutes).
The following deformation phase simulated a compressive
stress field (σ1≅σh) that was applied at the constant
velocity of 10 mm/h for seven hours.
The deformation of these models was mostly accommodated
by the dip-slip reactivation of pre-existing extensional
structures (fig. 1a), both in the basement and in the
basin fill, without the development of important newlyformed
structures away from these reactivated normal
faults.
The results of analogue models reported here suggest
a new triggering mechanism for diapiric rise during
basin inversion. This mechanism relates the localization
of ductile diapirs in correspondences of early normal
faults inverted during shortening. In this case, diapiric
growth is related to the strong dip-slip reactivation component
along the fault extruding upwards the siliconesimulating
salt.
In many places around the world, diapiric rise locally
developed along the reactivated extensional fault system.
For example, in the Nzala des Oudayas area (Saiss Basin,
Morocco), which is characterized by a Tertiary and Quaternary
shortening phases reactivating the Mesozoic
extensional structures (e.g. AIT BRAHIM et alii, 2002 and
references therein), the Triassic salt diapirs are directly
located above the inverted normal faults. The comparison
between the overall features of Nzala des Oudayas diapirs
(fig. 1b) with the model geometries (fig. 1a) allow us to
suggest that the triggering mechanism for this diapiric
structure could be most likely related to the syn-shortening
fault reactivation.