 |
| Titel |
Active tectonics and potential seismogenic behavior of newly imaged structures in the Gulf of Santa Eufemia (southern Italy) |
| VerfasserIn |
Maria Filomena Loreto, Fabrizio Zgur, Franco Pettenati, Lorenzo Facchin, Umberto Fracassi, Isabella Tomini |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250051004
|
|
|
|
|
|
| Zusammenfassung |
| During the summer of 2010 a wide geophysical, geological, bio-geochemical and
oceanographic dataset was acquired within the Gulf of Santa Eufemia (SE Tyrrhenian sea,
Italy). The aim of the project was to study the active tectonics of the region, including the
potential seismogenic structure responsible for the 8 September 1905 (Mw 7.5) earthquake,
which caused a 1.5 m of tsunami wave and several casualties and damage to the entire
Calabria region. To achieve this aim, 330 km of seismic data, 2223 km of Sub Bottom Chirp
profiles, and 2231 km2 of high resolution morpho-bathymetric data were acquired and
analyzed.
Morpho-bathymetry highlighted the presence of a deep and wide canyon, already
identified as Angitola Channel (Gamberi & Marani, 2004); this feature shows an E-W trend
in the sector toward the coast, and a meandering trend in the seaward segment. The first
segment of the channel shows a likely tectonic control, as imaged by Chirp profiles,
and could be associated with a likely N75Ë oriented transtensive structure. The
analysis of the seismic dataset shows that such tectonics locally affects the entire
sedimentary cover from Pre-Pliocene units up to the seafloor. The seismic images
also highlight another key structure trending about N113Ë , whose character is
defined by the sediments deformation and associable to a strike-slip fault with vertical
movements.
The top of Pre-Pliocene units, whose map was interpolated using the Kingdom software
(Seismic Micro-Technology Inc.), rises in the central part of the Gulf and deepens in the inner
sector close to the coast, near the Angitola Channel. While the analysis of the high resolution
morpho-bathymetric image yields no evidence of sediments deformations in the central part
of the Gulf, several gravitational instability scars are recognisable along the internal slope.
Moreover, several fluid escape features and mud volcanoes are recognized, even on
bathymetry and on Chirp data, from the coast toward the internal slope of subsea
sediments.
To obtain an hypothesis about the source location of the 1905 earthquake, the KF
inversion method (Pettenati and Sirovich, 2007), based on the macro-seismic intensity
catalogue data (Gruppo di Lavoro DBMI04, 2004), was applied. One preliminary solution of
the inversion is represented by a dip-slip structure, NNE-SSW oriented and located inside
the Gulf of Santa Eufemia close to the coast. Another possible solution defines a
structure with strike-slip motion, oriented N110 close to the Angitola Channel.
Although preliminary is still needing validation by historical seismograms, the latter
solution promisingly fits the transpressive structure identified in the Gulf. In spite of
this fact, the structure that controls the Angitola Channel must also be taken into
account.
1 References
Gamberi, F. & Marani, M.P.; 2004: Deep-sea depositional systems of the Tyrrhenian Basin.
In: From sea£oor to Deep Mantle: Architecture of the Tyrrhenian Backarc Basin
(Ed. By M. Marani, F. Gamberi & E. Bonatti), Mem. Desc. Carta Geol. d’It., 64,
127-146.
Gruppo di Lavoro DBMI04; 2004: Catalogo Parametrico dei Terremoti Italiani, versione
2004 (DBMI04). INGV Bologna, http://emidius.mi.ingv.it/DBMI04/
Pettenati, F., and L. Sirovich; 2007): Validation of intensity-based source inversion of
three destructive Californian Earthquakes. Bull. Seism. Soc. Am., 97, no. 5, 1587–1606. |
|
|
|
|
|
|