COMMENTS

Defining the present activity of the Mattinata Fault is the main issue for this source. 
The fault geomorphology is certainly impressive but a long tectonic history may have 
left a very strong geomorphic signature, especially durable in the calcareous rocks, 
that may make the fault appear still active even though it is not. This has been 
observed for other faults in calcareous rocks in the Apennines. Moreover, according 
to Argnani et al. (1993) no important deformation is seen offshore on the 
prolongation of the Mattinata Fault since Early Pliocene. However, seismicity occurs 
on this structure with small and moderate earthquakes possibly up to M 6.2.

On the basis of Piccardi's  (1998) interpretation of the Mattinata Fault as composed by 
three active sections, the easternmost of which is considered as an independent 
seismic source, we tentatively assume that also the rest of the fault be composed by 
other seismogenic sources. Based on historical seismicity, consistency with the Monte 
Sant'Angelo Source, and geometrical complexity of the fault trace, the Database 
includes another independent source in the central part of the Mattinata Fault 
between the Sant'Egidio basin and the town of San Giovanni Rotondo. 

Even though according to Piccardi's (1998) mapping this part of the fault dips to the 
south, the Database assumes that all the other geometrical parameters describing the 
fault geometry of the Monte Sant'Angelo Source can be, as a first approximation, be 
extended to this source. Its size was adjusted to fill the space left between the Monte 
Sant'Angelo and San Marco in Lamis sources. 

At least part of this source ruptured during the 18 August 1948, Me=5.4 earthquake.


OPEN QUESTIONS

1) How reliable are the inferred geometry and extent of this source? 

2) The Mattinata Fault is known as an important crustal structure with a long tectonic 
history. However, its evolution and kinematics are the matter of debate among 
structural geologists. Is this fault presently active? Is it a potential seismic source? If 
this is the case, is it a dextral or sinistral strike-slip fault?

3) Could the broad Mattinata Fault be the site of a continuous seismic release by small 
magnitude earthquakes instead of by a few large events? This is common in old 
major tectonic features in active regions. Could the 1948 (Me=5.4) and 1869 (Me= 5.0) 
earthquakes have released most of the stress on the San Giovanni Rotondo source?

4) Could the three portions of the Mattinata Fault defined by Piccardi (1998) and 
included in this Database be considered as fault segments in the sense of Schwartz 
and Coppersmith? If this is the case, how well defined are the segment boundaries? 

5) Conversely, can the three fault sections be part of a single larger seismogenic 
source?
