COMMENTS

The northern Marche coastal zone is presently affected only by low seismic activity, but 
damaging earthquakes struck this area in the recent past (e.g. in 1930, Senigallia). A 
NW-SE trending minimum stress axis and a NE-SW trending maximum 
compressional stress axis were shown respectively by bore-hole breakouts and 
earthquake focal mechanisms (Mariucci et al., 1999; Frepoli and Amato, 1997). The 
available field geological observations are still inadequate to devise a fully convincing 
correlation between the occurrence of earthquakes and realistic seismogenic sources. 
However, the most realistic hypothesis that can be envisaged to-date on the basis of the 
local geologic setting considers the blind thrust-faults located at the leading-edge of the 
Apennine accretionary prism as the main active and probably seismogenic faults in the 
area. In addition, it seems likely that two parallel fault-alignments of this sort exist 
along the northern Marche offshore.

The Rimini offshore South source is correlated with the 16 August 1916 Alto 
Adriatico earthquake. The seismogenic fault may be correlated with a blind thrust-
plane driving the growth of the offshore anticline and detected by Bally et al. (1986) 
through geophysical prospecting. The location, geometry and width of the fault at 
depth are based on the seismic reflection profile by Bally et al. (1986). Its size conforms 
to what is predicted by empirical relationships between length/width and magnitude 
relative to the 16 August 1916 Alto Adriatico earthquake.


OPEN QUESTIONS

1) This source suggest the presence of an active thrust fault in the Adriatic offshore. 
Could this fault belong to a longer fault system? 

2) How many parallel active thrust systems exist along the Adriatic coast?

3) Are these active fault-systems entirely seismogenic?


