Geophysical Abstracts 152 January-March 1953

GRAVITY 13
14206. Morelli, Carlo. Rilievo gravimetrico e riduzione isostatica nell Italia
Nord Orientale [Gravimetric survey and isostatic reduction in north­
eastern Italy]: Tecnica Italiana, v. 6, nos. 3 and 4, 1951; reprinted
in Univ. Padova, 1st. geod. e geofis., Pub. nuova ser., 6, 1951, and
Osservatorio Geofis. Trieste Pub., no. 20, 1951.
A gravimetric survey of the northeastern part of Italy, north of the Po River
and the east of longitude 10°10' East was made during 1950-51. Of 181 stations
included, 51 were reported by Cunietti in 1949-50 (see Geophys. Abs. 11931) 27
by Morelli in 1950 (see Abs. 12715), and the rest by Morelli in 1951. During
1951 a Worden gravimeter was used; during the 1949 and 1950 surveys a Western
gravimeter was used. The astronomical observatory of Padua, [0=980.658 gal]
was used as base station.
Airy-Heiskanen local anomalies were computed for equilibrium depths of
compensation of 20, 30, 40 and 60 km. Assuming Vening-Meinesz hypothesis of
regional isostatic equilibrium, the depth T was assumed equal to 30 km, with
radii of affected regions of 29.05 km, 116.20 km, and 232.40 km. Probable values
of density were taken from geologic maps of Italy.
It is pointed out that in spite of extreme care in computations and in measure­
ments, a difference in assumed density of 0.4 involves an error in reduction of a
station 1,000 m high above sea level of 17 mgal, making illusory the precision of
initial measurements of ±0.3 mgal. No isostatic equilibrium extending over the
whole area surveyed was found. The two main surfaces of seismic instability,
found by Mintrop from the analysis of seismological data obtained from the
Helgoland explosion of April 18, 1947, and Messina earthquake of December 28,
1908, corresponding to the maxima of gravitational gradient found here, suggest­
ing the existence of discontinuities where isostatic equilibrium has not yet been
reached. 8. T. V.
14207. Tribalto, Giuseppe, Zaccara, Gaetano and Beneo, Enzo. Misure gra-
vimetriche nella Valle Latina (Lazio) con deduzioni geologiche
[Gravimetric measurements in Valle Latina and their geologic inter­
pretations] : Servizio geol. Italia Boll., v. 73, fasc. 2, p. 357-370, 1952.
This is a detailed report of a gravimetric survey in Valle Latina, Italy, con­
sisting of 188 stations in an area of about 300 sq km. A western gravimeter was
used, with Rome (0=980.3600 gal) as the base station. The surveyed area was
divided into several closed polygons so that measurements were made twice at
each station. Station altitudes were taken from precise geodetic maps or deter­
mined by topographic leveling. In computing Bouguer reductions, density values
ranging from 1.9 to 2.3 were assumed in accordance with the geologic foundation
of the stations.
The results of the survey are presented in a table and on four maps of Bouguer
isoanomalies and residual gravity values. Geologic interpretations of the results
are presented in a separate section. 8. T. V.
14208. Cooper, R. I. B., Harrison, J. C., and Willmore, P. L. Gravity measure­
ments in the eastern Mediterranean: Royal Soc. London Philos. Trans.,
ser. A, v. 244, no. 889, p. 533-559,1952.
During 1950 measurements of gravity at sea were made in the submarine
Talent in the eastern Mediterranean. Forty-six stations were occupied in the
neighborhood of Malta and [Isola di] Pantelleria, 73 stations in the part of the
basin east of a line from Cape Matapan (Akra Tainaron) to Benghazi (Bengasi)
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