COMMENTS

Among the two source models available in current literature, the NNW-striking, E-
dipping normal fault proposed by De Martini (1996) and the WNW-striking, SW-
dipping lineament proposed by Vezzani (1967), Bousquet and Gueremy (1968) and 
Marra (1998), we selected the first as representative of the Mercure Source.

The Mercure Basin is located in a historical and instrumental seismic gap area and 
only recently two earthquake of moderate magnitude occurred (8 January 1988, Md 
4.1, and 9 September 1998, Ml 5.5). The lack of historical and instrumental evidence 
for stronger earthquakes in the northern Pollino area is substantial and could be 
explained as due:

a) to the incompleteness of the record, due to the scarcity of population and of 
settlements in the area (SGA, 1994; Valensise and Guidoboni, 1995);

b) to the occurrence of earthquakes with inter-event intervals longer than the time 
span covered by the historical record;

c) to a real absence of earthquakes, as the active deformation is adjusted aseismically 
because of particular local structural conditions.

We suspect that the answer to the lack of seismicity in the area is a combination of
point 1) and 2).

The Mercure normal fault proposed by De Martini (1996) is in good agreement with 
the structural data and the tectonic evolution presented by Schiattarella et al. (1994). 
In addition this source shows several similarities with the Castrovillari fault, located 
a few km to the south. In contrast with this interpretation some investigators 
(Vezzani, 1967; Bousquet and Gueremy, 1968) have suggested that the WNW-ESE 
striking, SW dipping Castelluccio-Viggianello lineament has been active until 
Rissian time as a normal fault, or, according to Marra (1998), with a predominant left 
lateral strike slip component, but the data supporting this last hypothesis are very 
limited.


OPEN QUESTIONS

1) What is the main seismogenic source in the area?

2) Is the Castelluccio-Viggianello Fault an obstacle for further northward propagation 
of the Mercure Fault, as suggested by the structural analysis? And thus is it a segment 
boundary or a transverse lineament?

3) If the Castelluccio-Viggianello Fault is active along its entire length (17 km), is it a 
normal or a strike-slip element? 

4) Can the Mercure Fault and the Castelluccio-Viggianello Fault slip at the same time 
for their entire length?

5) Should we expect aseismic slip on the Mercure Source?
