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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS005 Poster presentation 1921
Magnitude versus faults surface parameters: quantitative relationships
from the Aegean Region.
Prof. Riccardo Caputo
Dept. Earth Sciences University of Ferrara IASPEI
Pavlides S.
Historical and seismotectonic data from the broader Aegean Region have been collected and all possible
information relative to ground deformation associated to earthquakes that hit the area have been reevaluated.
All events associated to co-seismic surface faulting have been selected and further
investigated, while geomorphologic and geological criteria have been used to recognise and characterise
the seismogenic faults associated to these morphogenic earthquakes (sensu Caputo, 1993). In
particular, in order to perform seismic hazard analyses, we compiled a list of all earthquakes where the
surface rupture length (SRL), the maximum vertical displacement (MVD) or the average displacement
(AD) is available. We thus obtained reliable values of these source parameters for 36 earthquakes, of
which 26 occurred during the 20th century, 6 in the 19th century and the three remaining earlier.
Magnitude versus SRL and MVD have been compiled for estimating empirical relationships. The
calculated regression equations are: Ms = 0.90log(SRL) + 5.48 and Ms = 0.59log(MVD) + 6.75,
showing good correlation coefficients equal to 0.84 and 0.82, respectively. Co-seismic fault rupture
lengths and especially maximum displacements in the Aegean Region have systematically lower values
than the same parameters world-wide, but are similar to those of the Eastern Mediterranean-Middle
East region. The envelopes of our diagrams are also calculated and discussed for estimating the worstcase
scenario. Furthermore, for all investigated seismogenic structures, based on several geological
criteria, we measured the 'geological' fault length (GFL), representing the total length of the neotectonic
faults showing cumulative recent activity, and compared SRL with GFL. Eventually, from the distribution
of GFL versus magnitude we also infer an important geological threshold for the occurrence of
morphogenic earthquakes at about 5.5 degrees.
Keywords: seismic hazard, morphogenic earthquakes, seismotectonics