Interseismic coupling degree of Serre and Cittanova faults surface in
Southern Calabria, (Italy): New constraints from geodetic data
observations.
Abstract
Extensional faults in Southern Calabria (Italy) have been widely studied
for their capability to generate high magnitude earthquakes (Mw 7-7.2).
An example is the 1783 historical seismic sequence, which caused
numerous fatalities near the villages located along the largest fault
structures of this region, the Cittanova fault and the Serre fault. In
this paper, we estimated the seismic potential of these two faults by a
kinematic block modeling approach using GNSS data of both campaign
points and permanent stations available within this area. Our results
indicate that both faults are accommodating extensional velocity
gradient (~ 1 mm/yr), with long-term slip rates
(~ 2 mm/yr). A 3D mesh of triangular dislocation
elements (TDEs) was used to estimate the spatial variability of the
back-slip on fault planes, the corresponding interseismic coupling
degree and the resolution capability related to the data spreading. This
approach has allowed us to distinguish the fault areas where elastic
seismic rupture is more likely to happen from those affected by aseismic
creeping behaviour. Using our interseismic coupling results, we
estimated a set of possible rupture scenarios in Southern Calabria, as
well as calculated the corresponding interseismic moment accumulation
rate, comparing it to the coseismic moment release rate achieved by
previous studies. Thus, we achieved that, the Southern Calabria domain
is accumulating an interseimic moment rate at most equal to 1.09 ×1015
Nm/yr, the equivalent of an earthquake of Mw 4 for each year.