COMMENTS

The Barrea fault is included in the Database as a N152-striking, 50W-dipping fault 
rupturing between 5 and 11 km depth. The fault is characterised by prevalent normal 
slip, in agreement with Westaway et al. (1989) and Boncio et al. (1998).

The distribution of the aftershocks, concentrated within a cluster oriented ENE-
WSW, is rather anomalous. According to Boncio et al. (1998) they are controlled by 
two kinematically compatible structures: the normal fault (main seismogenetic 
structure) and a right-lateral normal oblique fault (assumed to have played the role of 
a transfer fault and of a barrier for the propagation of the rupture). In the Apennines, 
aftershock sequences that exhibit anomalous spatial patterns are often located at the 
intersection between two non-coaxial but kinematically compatible structures.

Although the 1984 earthquakes did not generate surface faulting, this source is 
currently reversing the topography, lowering the Monti della Meta and lifting the 
Sangro Valley. This appears to be a consistent feature of large normal faulting 
earthquakes all along the central and southern Apennines.


OPEN QUESTIONS

1) The 7 May 1984 earthquake occurred very close to the Aremogna-Cinque Miglia 
source, which is considered capable of substantially larger events but has not been 
active historically. What are the exact spatial relations between these two earthquake 
sources?

2) What are the relationships between the 7 May and 11 May shocks? Can the 11 May 
shock be interpreted as a large aftershock that occurred at the intersection with the 
transverse Barrea fault?

3) The Barrea source leaves a 10-15 km gap between itself and the Fucino Basin
source along the average direction of the Apennines. This stretch of the Apennines 
exhibits no background seismicity and some evidence for Holocene faulting. Can 
possible earthquake activity of this gap be foreseen based on currently available data?
