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Titel |
Ground instability in the old town of Agrigento (Italy) depicted by on-site investigations and Persistent Scatterers data |
VerfasserIn |
F. Cigna, C. Ventisette, G. Gigli, F. Menna, F. Agili, V. Liguori, N. Casagli |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1561-8633
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Digitales Dokument |
URL |
Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 12 ; Nr. 12, no. 12 (2012-12-06), S.3589-3603 |
Datensatznummer |
250011252
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Publikation (Nr.) |
copernicus.org/nhess-12-3589-2012.pdf |
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Zusammenfassung |
We combine on-site investigations with the interpretation of satellite
Persistent Scatterers (PS) to analyse ground instability in the historic
town of Agrigento, Italy. Geological and geomorphologic surveys, together
with geostructural and kinematic analyses, depict the deformational patterns
of the northwestern sector of the town, previously documented by extensive
literature available for the neighbouring Valley of the Temples. The
geological and geomorphologic maps are reconstructed by combining
bibliographic studies, field surveys and aerial stereo-interpretation.
ERS-1/2 PS data reveal deformation velocities up to 18–20 mm yr−1 in 1992–2000
over the Addolorata landslide, and a sudden motion of 1.6 cm over the
Bishop's Seminary in 1999. RADARSAT-1 PS data highlight velocities of 3.0 mm yr−1
for St. Gerlando's Cathedral and reveals worsening of its structural
instability since 2006. Ground instability of the town is controlled by low
quality and high fracturing of the Agrigento formation rock masses, and the
remarkable contrast between different mechanical behaviours of its
calcarenite (brittle), silt and clay (plastic) facies. Slow landslides and
widespread erosion are also recognised in the clays of the underlying Monte
Narbone formation. Coexistence of these factors induces progressive
retrogression of the edge of the Girgenti hill and damages the overlying
historic buildings, whose stability and safe accessibility are nowadays
almost compromised. |
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