The Italian present-day stress map
Geophysical Journal International, 189 (2):
705--716 (2012)DOI: 10.1111/j.1365-246X.2012.05391.x
Zusammenfassung
In this paper, we present a significant update of the Italian present-day
stress data compilation not only to improve the knowledge on the
tectonic setting of the region or to constrain future geodynamic
models, but also to understand the mechanics of processes linked
to faulting and earthquakes. In this paper, we have analysed, revised
and collected new contemporary stress data from borehole breakouts
and we have assembled earthquake and fault data. In total, 206 new
quality-ranked entries complete the definition of the horizontal
stress orientation and tectonic regime in some areas, and bring new
information mainly in Sicily and along the Apenninic belt. Now the
global Italian data set consists of 715 data points, including 499
of A-C quality, representing an increase of 37 per cent compared
to the previous compilation. The alignment of horizontal stresses
measured in some regions, closely matches the Ñ-S first-order
stress field orientation of ongoing relative crustal motions between
Eurasia and Africa plates. The Apenninic belt shows a diffuse extensional
stress regime indicating a ÑE-SW direction of extension, that
we interpret as related to a second-order stress field. The horizontal
stress rotations observed in peculiar areas reflect a complex interaction
between first-order stress field and local effects revealing the
importance of the tectonic structure orientations. In particular,
in Sicily the new data delineate a more complete tectonic picture
evidencing adjacent areas characterized by distinct stress regime:
northern offshore of Sicily and in the Hyblean plateau the alignment
of horizontal stresses is consistent with the crustal motions, whereas
different directions have been observed along the belt and foredeep.