Geophysical data acquisition - OGS

The Marche Microzonation Project is a two-year research project, whose general
objective is the detailed microzonation of some selected cities of the Marche
Region. The OGS contribution develops within the second year of the project. The
aim is to perform a detailed simulation of the ground motion and site response
analysis for the cities of Treia (MC) and Cagli (PS). Numerical simulations are
performed using the SPEM. The reference event is a M=5.7 earthquake, and it is
associated to two normal faults located beneath the cities, respectively. The second
Figure shows a wavefield snapshot for the simulations performed for Treia.
Marche
Microzonation
Project. Wavefield
snapshot (P-SV
acceleration) of the
SPEM simulation
performed for the
town of Treia
(Macerata, Marche,
Italy). The locations
of the town and
source are
indicated at the top
and by the couple
of arrows,
respectively.
Within the project entitled Damage Scenarios in the Veneto-Friuli Area, the
activity of the first year aims at building-up a ground shaking scenario at a regional
scale for the area surrounding the town of Vittorio Veneto. The reference
earthquake is the M=5.8 event, which occurred in “Cansiglio” on October 14, 1936.
The associated fault mechanism is oblique, with a strong character of reverse fault.
Both point source models and rupture propagation along an extended fault are
considered. The dominant feature of the geological structure is the thrust
corresponding to the Alpago-Cansiglio highlands, the southern edge of which
features a very steep change of elevation. The reference earthquake is associated to
this thrust. The particular location of the source, which is rather deep and right in
the middle of a structural discontinuity, makes it possible to tackle this study with
a non classical approach, that is differentiating the surface structure and top
elevation in different zones, i.e., the plane area, the foot-hill zone, the alpine
valleys, and the mountain area, respectively. The areas of maximum ground
shaking predicted in this way agree very well with those observed in the
macroseismic field (third Figure) even just by using a point source.
31