De Panfilis and Marcelli (1968)
These workers describe extensively the sequence of events that occurred 
between 14 January and 10 June 1968, discussing the frequency and 
distribution of 25 of them. Because the events occurred close in space and time 
they drew an isoblabe map (points with same damage produced during 
subsequent events) instead of an isoseismal map. 

Bosi et al. (1968) and Bosi et al. (1973)
Following the results of a previous study, these workers describe the 
geomorphic characteristics of the area struck by the 1968 earthquake sequence 
and point out some relationships between geology and seismology. They 
conclude that the seismic events did not produced new faults or rejuvenated 
pre-existing faults. Ground surface effect occurred such as landslides and sand 
blows. Most of the epicentres appear located along two lineaments: the 
Castelvetrano-Monte Finestrelle and Montevago-Bisaquino-Corleone 
lineaments, that are interpreted as seismically active. Based on the survey of 
buildings damages located in areas with similar geotechnical characteristics 
they also evaluated an average degree of damage. 

Marcelli and Pannocchia (1971)
They recalculate analytically the hypocentres of 10 earthquakes that occurred 
in Western Sicily in January 1968, providing better constraints on their 
location with respect to previous studies. The magnitude of these events 
ranges between 6 (for the mainshock) and 4.3. These earthquakes are mainly 
distributed along the Belice River Valley within an area of about 550 km2 and 
with reported hypocentral depths ranging between 28 and 57 km. 

McKenzie (1972)
This investigator recalculates the location and proposes a focal mechanism for 
some of the earthquakes that occurred during the 1968 sequence (15, 16 and 25 
January). The main results are consistent with thrusting on East-West planes. 
For the author the intrinsic ambiguity between the two planes cannot be 
resolved for any of these events.

Bottari (1973)
This paper determines the hypocentral parameters of 14 events of the 
sequence with M>4.4 and finds agreement with previous seismotectonic 
interpretations of the area. Unlike previous studies, here the author includes 
data from stations located far from the epicentre and evaluates focal depth 
between 0 and 28 km. The epicentres align along a 30 km- long NE-SW trend 
that appears parallel to the lineaments identified by Bosi et al. (1973). Using 
first motion polarities for the main shock (15 January , M=5.6) the author 
suggests a main fault plane striking N11E and dipping 75 to the W, with P 
and T axes oriented N34W and N56E respectively. 

Cardamone et al. (1976)
These workers analyse regional features of central Sicily using satellite images. 
They compare these lineations with actual faulting and hypothesise that the 
1968 earthquake sequence is evidence of active N-S faulting. They show also a 
deep seismic refraction line in southwestern Sicily showing a crustal 
shortening from the Sicily channel towards the Tyrrhenian.

Anderson and Jackson (1987)
These investigators study the 15, 16 and 25 January 1968 events and indicate 
for the main shock an Mb=5.4. Their locations suggest a N-S alignment which 
cannot be related to any recent fault or major structural trend. They find a 
relatively shallow location for most of the events. In their calculated focal 
mechanisms the polarity remain ambiguous because are satisfied either by a 
pure E-W thrust plane or by a prevalently right lateral movement on a NNW 
striking, WSW-dipping plane. Because of the alignment of the relocated 
epicentres in a northerly direction, the authors suggests a NNW-striking 
plane with strike slip component as preferred rupture plane.

Michetti at al. (1995)
This paper presents paleoseismological studies conducted in the epicentral 
area of the 1968 earthquake. They locate two sites for trenching based the 
investigation on the ground effects produced by the earthquake sequence and. 
The Molino Nuovo trench was excavated in the fluvial sediments where 
coseismic sand blows occurred but no evidence of paleo-liquefaction is found. 
At the Monte Porcello site eyewitness observed ground fractures in the 
bedrock shortly after the earthquakes, and the authors identify a previously 
unknown Quaternary fault (the Monte Porcello Fault, MPF). At this site they 
excavate four trenches and find evidence of paleoseismicity. They conclude 
that the MPF ruptured during the 1968 earthquake and is capable of producing 
coseismic surface displacement larger than those observed in 1968. The 
geometry and kinematics of the MPF are consistent with focal mechanisms 
and neotectonic evidence for a regional, NS-trending, right lateral 
transcurrent zone within the Belice region.

Monaco et al. (1997)
These investigators point out that the 1968 sequence took place in a region 
that lacks any evidence in the topography of lineaments likely to result from 
fault activity. They contend that the instrumental data show that the largest 
shocks are distributed along a roughly N-dipping plane and that published 
fault plane solutions indicate pure thrusting on N-dipping, ENE- trending 
planes, or oblique slip with s right-lateral component of motion along WSW- 
dipping planes both as a result of approximate N-S shortening. Based on 
macroseismic effects they identify an elongation of the isoseismal in a ENE 
direction that is shown also by the epicentral distribution of events with M4. 
They point out that this area is located 20 km NW of the Sciacca-Rocca Ficuzza 
thrust fault, a possibly active regional morphotectonic feature (tentatively 
dated at 1.0-0.7 Myr) close to the epicentral area. Their conclusion is that 
seismological, structural and morphotectonic observations suggest that 
multiple ruptures might have occurred on a blind crustal thrust ramp located 
beneath the epicentral area and that the slip propagated southwestward along 
the shallow ramp- flat system characterising the thin-skinned foreland fold 
and thrust belt of southwestern Sicily.

Morelli and Pondrelli (1998)
These workers calculated a centroid moment tensor solution indicating a 
EW-trending, N-dipping, oblique thrust and a Mw= 5.6 for the mainshock.

Ragg et al. (1999)
These workers analyse the orientation of in situ tectonic stress deduced from 
borehole breakout in Sicily. The paper separates several tectonic units with 
characteristic stress patterns. In western Sicily they measured a SHmax 
orientation that ranges from N to NW and conclude that this fits well with 
the N-S shortening inferred from the focal mechanisms of the January 1968 
earthquake sequence (5<M5.4). They interpret the active development of 
these thrust belts as due to the oblique convergence and intraplate 
deformation observed along this sector of the northern margin of the Africa 
plate.
