Dissertation committee:
Μακρόπουλος Κωνσταντίνος Ομότ. Καθηγητής ΕΚΠΑ (επιβλέπων), Κουσκουνά Βασιλική Αναπλ. Καθηγήτρια, Κασσάρας Ιωάννης Επίκ. Καθηγητής
Summary:
The scope of this thesis is the development and evaluation of a seismic risk
model in a building by building scale within the old town of Lefkada, capital
of Lefkada Island, Greece. Lefkada is part of the Ionian Islands, a most
seismically active area in Greece that has suffered numerous destructive
earthquakes. Most of the buildings of the historical center of the town were
built by local practices and have been designated as representative earthquake
resistant constructions by the European Council Cultural Heritage Unit. The
town is situated on low resistance and rigidity Holocene alluvial and lagoon
deposits of 9 to 16 meter thickness. The local amplification of ground motion
typically depends on the soil deposits.
The proposed model derived by combining seismic sources, building vulnerability
and site effects. Vulnerability was assessed empirically for individual
buildings through a field survey using the assumption of EMS-98. Site effects
were determined using ambient noise HVSR measurements at selected points in LOT
and geotechnical data. Peak ground acceleration was assessed using both the
finite fault and the point-source stochastic simulation scheme, taking into
account the local amplification factor derived by ambient noise measurements.
Seismic risk scenarios were developed through employing two seismic sources:
(a) the earthquake of August 14th 2003, Mw=6.2 and (b) a future Maximum
Credible Earthquake of Mw=7.0, expected at the same distance according to the
probabilistic seismic hazard analysis elaborated. Moreover, the discrete damage
state probability for each building was resolved. The estimated seismic damage
scenarios correlate very well to the observed damage for a large number of
buildings, thus implying that the proposed model is a reliable one. The
buildings of Lefkada old town present satisfactory seismic behavior under the
load of an earthquake similar to the one of 2003, but are susceptible to
serious damage in case of a stronger earthquake.
Keywords:
Structural vulnerability, Site effects, Seismic risk, Stochastic simulation, Traditional buildings of Lefkada
