Teresa Nolesini, Federico Di Traglia, Chiara Del Ventisette, Sandro Moretti, Nicola Casagli
To understand the relationship between volcano deformations, magma overpressure and flank instabi... more To understand the relationship between volcano deformations, magma overpressure and flank instability, the results of analogue experiments of slope instability and ground deformations, recorded by the GBInSAR system on the western flank of the Stromboli volcano during the period 2009–2011 have been analyzed. Analogue experiments that consider both the external (accumulation on the slope) and the endogenous (intrusion-related bulging) trigger phenomena. The effect of accumulation on the sub-aqueous slope on the initiation of sub-marine mass movements has been analyzed. By combining the monitoring data with analogue modeling, the observed deformations from the combined action of overpressure in the volcanic system and gravity have been related. The results suggest that the superficial movements observed by the GBInSAR system represent the response of the Stromboli volcano to overpressure changes in the conduit. The movements observed on the Sciara del Fuoco were slope instability phenomena where the gravitational component produced a constant creep, while changes in the magma overpressure explain why certain periods are characterized by accelerations, which induce instability on the external flanks of the crater area and in the Sciara del Fuoco and eventually promote failure of the volcanic slopes.
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triggered hundreds of landslides (predominantly debris
flows) in an area of about 50 km2 in the north-eastern sector
of Sicily (Italy). Debris flows swept the highest parts of
many villages and passed over the SS114 state highway and
the Messina-Catania railway, causing more than 30 fatalities.
This region has a high relief, due to recent uplift. The peculiar
geological and geomorphological framework represents
one of the most common predisposing causes of rainstormtriggered
debris flows. This paper deals with the geological
and hydro-geomorphological studies performed as a part
of the post-disaster activities operated in collaboration with
Civil Protection Authority, with the aim at examining landslides
effects and mechanisms. The data were elaborated into
a GIS platform, to evaluate the influence of urbanisation on
the drainage pattern, and were correlated with the lithological
and structural framework of the area.
Our study points at the evaluation of the volume involved,
the detection of triggering mechanisms and the precise reconstruction
of the influence of urbanisation as fundamental
tools for understanding the dynamics of catastrophic landslides.
This kind of analysis, including all the desirable approaches
for the correct management of debris flow should
be the starting point for robust urban planning.
paper amultidisciplinary approach to derive a 1:2000 geomorphologicalmap is described.The proposedmethodology
consists of the integration between aerial photographs, acquired in 2003, and four datasets of Persistent Scatterer
Interferometry (PSI) measures to update a pre-existing landslide inventory. The integrated data were used to
achieve a validated geomorphological map by means of a geomorphological survey. The study area is located in
southern Italy (Agrigento, Sicily). The city of Agrigento, included in the World Heritage List of UNESCO in 1997,
is located on the Girgenti hill which is exposed on its northern side, to several landslide phenomena. The top of the
hill is characterized by the presence of part of the cultural heritage of the city and is affected by rockfalls, rock
topples and shallow-seated landslides, representing a serious risk for important historical buildings. The results
demonstrate the validity of this method to achieve a suitable tool in landscape and cultural heritage management.
Keywords: geomorphology; PSInSAR; remote sensing; cultural heritage; Agrigento; landslides; geomorphology;
radar
styles in basaltic monogenetic volcanoes, with particular emphasis on the role of phreatomagmatism in
triggering Violent Strombolian eruptions. Croscat volcano, an 11 ka basaltic complex scoria cone in the
Quaternary Garrotxa Volcanic Field (GVF) shows pyroclastic deposits related both to magmatic and
phreatomagmatic explosions.
Lithofacies analysis, grain size distribution, chemical composition, glass shard morphologies, vesicularity,
bubble-number density and crystallinity of the Croscat pyroclastic succession have been used to characterize
the different eruptive styles. Eruptions at Croscat began with fissural Hawaiian-type fountaining that rapidly
changed to eruption types transitional between Hawaiian and Strombolian from a central vent. A first
phreatomagmatic phase occurred by the interaction between magma and water from a shallow aquifer
system at the waning of the Hawaiian- and Strombolian-types stage. A Violent Strombolian explosion then
occurred, producing a widespread (8 km2
), voluminous tephra blanket. The related deposits are
characterized by the presence of wood-shaped, highly vesicular scoriae. Glass-bearing xenoliths (buchites)
are also present within the deposit. At the waning of the Violent Strombolian phase a second
phreatomagmatic phase occurred, producing a second voluminous deposit dispersed over 8.4 km2
. The
eruption ended with a lava flow emission and consequent breaching of the western-side of the volcano. Our
data suggest that the Croscat Violent Strombolian phase was related to the ascent of deeper, crystal-poor,
highly vesicular magma under fast decompression rate. Particles and vesicles elongation and brittle failure
observed in the wood-shaped clasts indicate that fragmentation during Violent Strombolian phase was
enhanced by high strain-rate of the magma within the conduit.
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.
triggered hundreds of landslides (predominantly debris
flows) in an area of about 50 km2 in the north-eastern sector
of Sicily (Italy). Debris flows swept the highest parts of
many villages and passed over the SS114 state highway and
the Messina-Catania railway, causing more than 30 fatalities.
This region has a high relief, due to recent uplift. The peculiar
geological and geomorphological framework represents
one of the most common predisposing causes of rainstormtriggered
debris flows. This paper deals with the geological
and hydro-geomorphological studies performed as a part
of the post-disaster activities operated in collaboration with
Civil Protection Authority, with the aim at examining landslides
effects and mechanisms. The data were elaborated into
a GIS platform, to evaluate the influence of urbanisation on
the drainage pattern, and were correlated with the lithological
and structural framework of the area.
Our study points at the evaluation of the volume involved,
the detection of triggering mechanisms and the precise reconstruction
of the influence of urbanisation as fundamental
tools for understanding the dynamics of catastrophic landslides.
This kind of analysis, including all the desirable approaches
for the correct management of debris flow should
be the starting point for robust urban planning.
paper amultidisciplinary approach to derive a 1:2000 geomorphologicalmap is described.The proposedmethodology
consists of the integration between aerial photographs, acquired in 2003, and four datasets of Persistent Scatterer
Interferometry (PSI) measures to update a pre-existing landslide inventory. The integrated data were used to
achieve a validated geomorphological map by means of a geomorphological survey. The study area is located in
southern Italy (Agrigento, Sicily). The city of Agrigento, included in the World Heritage List of UNESCO in 1997,
is located on the Girgenti hill which is exposed on its northern side, to several landslide phenomena. The top of the
hill is characterized by the presence of part of the cultural heritage of the city and is affected by rockfalls, rock
topples and shallow-seated landslides, representing a serious risk for important historical buildings. The results
demonstrate the validity of this method to achieve a suitable tool in landscape and cultural heritage management.
Keywords: geomorphology; PSInSAR; remote sensing; cultural heritage; Agrigento; landslides; geomorphology;
radar
styles in basaltic monogenetic volcanoes, with particular emphasis on the role of phreatomagmatism in
triggering Violent Strombolian eruptions. Croscat volcano, an 11 ka basaltic complex scoria cone in the
Quaternary Garrotxa Volcanic Field (GVF) shows pyroclastic deposits related both to magmatic and
phreatomagmatic explosions.
Lithofacies analysis, grain size distribution, chemical composition, glass shard morphologies, vesicularity,
bubble-number density and crystallinity of the Croscat pyroclastic succession have been used to characterize
the different eruptive styles. Eruptions at Croscat began with fissural Hawaiian-type fountaining that rapidly
changed to eruption types transitional between Hawaiian and Strombolian from a central vent. A first
phreatomagmatic phase occurred by the interaction between magma and water from a shallow aquifer
system at the waning of the Hawaiian- and Strombolian-types stage. A Violent Strombolian explosion then
occurred, producing a widespread (8 km2
), voluminous tephra blanket. The related deposits are
characterized by the presence of wood-shaped, highly vesicular scoriae. Glass-bearing xenoliths (buchites)
are also present within the deposit. At the waning of the Violent Strombolian phase a second
phreatomagmatic phase occurred, producing a second voluminous deposit dispersed over 8.4 km2
. The
eruption ended with a lava flow emission and consequent breaching of the western-side of the volcano. Our
data suggest that the Croscat Violent Strombolian phase was related to the ascent of deeper, crystal-poor,
highly vesicular magma under fast decompression rate. Particles and vesicles elongation and brittle failure
observed in the wood-shaped clasts indicate that fragmentation during Violent Strombolian phase was
enhanced by high strain-rate of the magma within the conduit.
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.