Geophysical Abstracts 152 January-March 1953

SEISMOLOGY 39*
14309. Fontsere, Eduardo. Los terablores de tierra Catalones del ano 1950
[Earthquakes in Catalonia during 1950] : R. Acad. Cien. y Artes de Bar­
celona Observatorio Fabra Bol. 39, p. 343-347, 1952.
Data on the earthquakes of January 31, June 21, June 28, and October 20-23-
and the explosion of June 6 are given. Isoseismal maps are included for the-
shocks of January 31 and June 28. M. C. R.
|- I^onafehov, F. I. Kharakteristika afganskikh glubokofokus&jskh zemletry-
aseniy [The characteristics of deep focus earthquakes in Afghanistan] ^
Akad. Nauk SSSR Geofiz. Inst. Trudy no. 14(141) , p. 3-12, 1952.
Epicenters and depths of focus of 37 earthquakes which occurred in different
regions of Afghanistan between November 1946 and December 1948 were deter­
mined from seismograms of the observatories of Kulyab, Stalinabad, Obi-Garm,.
and Murgab. The depths ranged from 100 to 250 km. The direction of initial
shock at the focus was also determined. The results are in good agreement with.
generally accepted ideas on tectonic movements in this region. 8. T. V.
14311. Burke-Gaffney, T. N. Seismicity of Australia: Royal Soc. New
Wales Jour, and Proc., v. 85, pt. 2, p. 47-52, 1952.
Seismological data on about 75 earthquakes which occurred in Australia from
1883 till 1949 are presented, only including those tremors which originated
within the Australian continental shelf; epicenters and the Gutenberg-Richter
magnitudes of all shocks are given. The greatest intensity of observed earth­
quakes was 7 (modified Mercalli scale). It is concluded that Australia is one
of seismically stable regions of the earth. 8. T. V.
14312. DuQgen, F. H. Van den, Cox, J. F., and Mieghern, J. Van. Fluctuations
de la rotation de la terre et seismicitS [Fluctuations of the rotation of
the earth and seisrnicity] : Acad. Royale Belgique Bull., Cl. sci., 5°
ser., tome 38, p. 607-611, 1952.
In continued studies of the correlation between seasonal fluctuations of the
earth's rotation and earthquake frequencies an analysis was made of statistical
data on earthquakes collected by several seismologists and the study of the
variation of the rotation of the earth by Stoyko (see Geophys. Abs. 13291) and
the conclusion drawn that the frequency of earthquakes becomes greater during
the periods when decreasing rotational velocity changes to increasing. The
change of rotation seems to be the primary factor, but displacement of masses
resulting from ensuing earthquakes in turn changes the velocity of rotation,
because of the variation in the moment of inertia. 8. T. V.
14313. Dungen, F. H. Van den, Cox, J. F., and Mieghem, J. Van. Sur la p4riode
annuelle de la frequences des seismes [On the annual periodicity of the-
frequency of earthquakes] : Acad. Royale Belgique Bull. 01. sci., 5"
ser., tome 37, p. 1037-1043, 1952.
Statistical data on earthquakes collected at Uccle during the years 1910-1945
were analyzed and a curve of average frequency of earthquakes for different
months of the year was constructed. A pronounced maximum is observed in
August and a minimum in the last week of February. Spanish seismologists
have previously established a similar periodicity with a maximum in July and
a minimum in January. It is suggested as a contributing factor that the crust:
rotates slightly faster (0.001 second per day) than the substrata. S. T. V.