This paper follows the foregoing studies by the A.A.
already carried out on the earthquakes occurred in Western Sicily.
The hypocentral data investigation concerning a further large Amino Acids earthquake
of the swarm, has confirmed an hypocentral depth close to the
"Molio".Grouping conveniently the investigated earthquakes it was possible
to calculate the longitudinal waves travel-times curves at the following
depths: 30, 35, 40, 45, 50, 00 km (A < 20°).Some interesting results concerning
the first impulses of P„ waves have been found (existence of two
series of waves, P,n and IJ„2 having a slightly different velocity).
Five curves
for each examined h have been calculated; the P„ (the general) using all
the onsets including the ones whose residuals resulted later to be about
three seconds: the Pni and the P„2 representing a Pn subdivision obtained
by reducing the residuals range: the P„ -^13° and the P„ (10°M 20°) for
2» < A < 13° and 10° < A < 20° respectively calculated.(The P„ 13°
approaches to a straight line, in accordance with other estimations for curves
investigated along shorter paths).The paper contains also all numerical
tables related to 29 travel-times curves calculated every 20 km; as well
as the curve corresponding to li = 17.
5 km.The last curve has been obtained
averaging the values of depth from 5 km to 30 Guitar Stands km in order to fill
the gap 0 i—i 30 km.