Vol. 51, n.1, March 2010
2D versus 1D ground-motion modelling for the Friuli region, north-eastern Italy
W. IMPERATORI, H. AOCHI, P. SUHADOLC, J. DOUGLAS, A. DUCELLIER and G. COSTA
Received: September 15, 2008; accepted: April 28, 2009
We perform a series of simulations of seismic wave propagation from potential
earthquakes to evaluate how the 2D (in the NW-SE direction) geological structure of
the Friuli (NE Italy) basin affects ground motions, particularly in terms of peak ground
velocity (PGV). The decay of PGV with source-receiver distance from the 2D
modelling is compared to that obtained from 1D modelling, using a standard model
for seismological studies in this region, one obtained by averaging the 2D model along
the source-receiver distance and one based on the local structure under the receiver.
Synthetic seismograms are computed using a finite-difference technique for point
sources with an upper frequency cut-off of 0.6 Hz. 2D effects are clearly seen,
particularly in the centre of the sedimentary basin, for certain earthquake scenarios.
The analysis of the role played by the main heterogeneities on the propagating
wavefield permits us to conclude that an acceptable fit to the 2D PGV values for the
entire section is possible using a series of 1D models for the Friuli region except for
shallow earthquakes located to the north-west of the basin, where the structure of the
basin edge is complex.
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