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| Titel |
Seismic hazard assessment in the Catania and Siracusa urban areas (Italy) through different approaches |
| VerfasserIn |
Francesco Panzera, Giuseppe Lombardo, Rosaria Rigano |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250032192
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| Zusammenfassung |
| The seismic hazard assessment (SHA) can be performed using either Deterministic or
Probabilistic approaches. In present study a probabilistic analysis was carried out for the
Catania and Siracusa towns using two different procedures: the “site” (Albarello and
Mucciarelli, 2002) and the “seismotectonic” (Cornell 1968; Esteva, 1967) methodologies.
The SASHA code (D’Amico and Albarello, 2007) was used to calculate seismic hazard
through the “site” approach, whereas the CRISIS2007 code (Ordaz et al., 2007) was adopted
in the Esteva-Cornell procedure. According to current international conventions for PSHA
(SSHAC, 1997), a logic tree approach was followed to consider and reduce the
epistemic uncertainties, for both seismotectonic and site methods. The code SASHA
handles the intensity data taking into account the macroseismic information of past
earthquakes. CRISIS2007 code needs, as input elements, a seismic catalogue tested for
completeness, a seismogenetic zonation and ground motion predicting equations. Data
concerning the characterization of regional seismic sources and ground motion
attenuation properties were taken from the literature. Special care was devoted to
define source zone models, taking into account the most recent studies on regional
seismotectonic features and, in particular, the possibility of considering the Malta
escarpment as a potential source. The combined use of the above mentioned approaches
allowed us to obtain useful elements to define the site seismic hazard in Catania and
Siracusa. The results point out that the choice of the probabilistic model plays a
fundamental role. It is indeed observed that when the site intensity data are used, the town
of Catania shows hazard values higher than the ones found for Siracusa, for each
considered return period. On the contrary, when the Esteva-Cornell method is used,
Siracusa urban area shows higher hazard than Catania, for return periods greater
than one hundred years. The higher hazard observed, through the site approach, for
Catania area can be interpreted in terms of greater damage historically observed at
this town and its smaller distance from the seismogenic structures. On the other
hand, the higher level of hazard found for Siracusa, throughout the Esteva-Cornell
approach, could be a consequence of the features of such method which spreads out the
intensities over a wide area. However, in SHA the use of a combined approach is
recommended for a mutual validation of obtained results and any choice between
the two approaches is strictly linked to the knowledge of the local seismotectonic
features.
References
Albarello D. and Mucciarelli M.; 2002: Seismic hazard estimates using ill?defined
macroseismic data at site. Pure Appl. Geophys., 159, 1289?1304.
Cornell C.A.; 1968: Engineering seismic risk analysis. Bull. Seism. Soc. Am., 58(5),
1583-1606.
D’Amico V. and Albarello D.; 2007: Codice per il calcolo della pericolosità sismica da
dati di sito (freeware). Progetto DPC-INGV S1, http://esse1.mi.ingv.it/d12.html
Esteva L.; 1967: Criterios para la construcción de espectros para diseño sísmico.
Proceedings of XII Jornadas Sudamericanas de Ingeniería Estructural y III Simposio
Panamericano de Estructuras, Caracas, 1967. Published later in Boletín del Instituto
de Materiales y Modelos Estructurales, Universidad Central de Venezuela, No.
19.
Ordaz M., Aguilar A. and Arboleda J.; 2007: CRISIS2007, Program for computing
seismic hazard. Version 5.4, Mexico City: UNAM.
SSHAC (Senior Seismic Hazard Analysis Committee); 1997: Recommendations for
probabilistic seismic hazard analysis: guidance on uncertainty and use of experts.
NUREG/CR-6372. |
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