Near field domain effects and their consideration in the international and Italian seismic codes

TitleNear field domain effects and their consideration in the international and Italian seismic codes
Publication TypeJournal Article
Year of Publication2014
AuthorsGrimaz S, Malisan P
JournalBollettino di Geofisica Teorica ed Applicata
ISSN Number0006-6729

It is widely proven that in the field area near a seismic source the characteristics of
the seismic ground motion (near field) could be meaningfully different from those far
from the source (far field), not only in terms of intensity but also in terms of nature and
typology. Nevertheless, structures are usually designed on the base of accelerations
derived from ordinary probabilistic seismic hazard analyses (PSHA) under the
hypothesis of far-field conditions, and further modified taking into account the local
seismic response. As a consequence, a structure might not have proper safety levels if
it is located close to an earthquake source (i.e., in a potential near-field domain). The
purpose of this paper is to analyse the near-field effects on the seismic hazard, focusing
in particular on the Italian case. For this aim, an essential bibliographic overview is
presented, showing the specific seismic effects in the proximity of an earthquake source
and the related consequences on the structures. Furthermore, the paper presents a brief
analysis on how some international seismic building codes consider the near-field
effects, underlining the fact that, nowadays, the near field effects are not considered
in the Italian codes. For this reason, the authors suggest to consider the increase of
the seismic demand in the potential near-field domains, introducing the concept of
“potential epicentral area contribution to hazard – PEACH”, directly associated to the
specific characteristics of the seismogenic source. Finally, the limits of the proposed
approach and the prospective of its application in Italy are outlined.