Some characteristics of the seismicity of the Tyrrhenian Sea Region

Main Article Content



In the first p a r t of the paper the seismic strain release
of the T y r r h e n i a n Sea Region (including Italy), as the function of time,
is examined on the basis of t h e d a t a of the e a r t h q u a k e s t h a t took place
f r om 1901.01.01 to 1970.12.31, between the northern l a t i t u d e s of 34° and
44° and between the eastern longitudes of 8° and 18.5°, respectively. All
registered shocks with a R i c h t e r - m a g n i t u d e of 5.5 or over it were considered,
i n d e p e n d e n t l y f r om t h e focal d e p t h . Three periods were recognized in the
a c t i v i t y ; t h e lengths of which are not t h e same, however.
I n the second p a r t the elastic strain release in accordance with the
focal d e p t h of t h e same e a r t h q u a k e s is t r e a t e d briefly. It was found t h at
t h e t o t a l strain-release had a maximum value in t h e depth between 0 and
74 kms and there was a minimum between the depth of 300 and 524 kins
with an interval between 375 and 449 kms within which no earthquakes
occurred at all. The general p a t t e r n of the d i s t r i b u t i o n of seismicity as
t h e f u n c t i o n of hypocentral d e p t h reminds to the well-known picture, one
can experience in other regions where i n t e r m e d i a t e and deep shocks occur.
This s t a t e m e n t is consistent w i t h t h e idea, according to which t h e seismicity
of t h e Tyrrhenian Sea Region can be discussed and explained in t h e light
of t h e theory of new global tectonics.
F i n a l l y , in the t h i r d p a r t of the study, the authors have s t a t e d t h at
in some cases multiple events occurred b e n e a t h t h e Tyrrhenian Sea Region.
Such multiple seismic events were detected in the case of other areas, such
as the Fiji-Tonga-Kermadec Region, the seismic belt of South America
etc., — but, according to the knowledge of t h e authors, this is t h e first occasion
when multiple seismic events are demonstrated in the Tyrrhenian
Sea Region.

Article Details

How to Cite
MESZAROS, S. and HEDERVARI, P. (1974) “Some characteristics of the seismicity of the Tyrrhenian Sea Region”, Annals of Geophysics, 27(1-2), pp. 367–380. doi: 10.4401/ag-4929.