On locating local earthquakes at the Messina Strait network
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Abstract
A computer program (HYPOSTRE) has been elaborated to determine
the hypocentral parameters of local earthquakes, even when they are recorded
by a small number of stations. These are the most frequent conditions
prevailing around the Strait of Messina.
The program employs the first arrivals of P and S waves, a model of
local crust consisting of four plane and parallel layers, and an algorithm
based on that of Geiger.
HYPOSTRE can determine simultaneously the four unknowns X, cp, h
and H (HYPOSTRE 4) and can calculate the epicentral coordinate separately
from focal depth (HYPOSTRE 2). In both cases the program follows
an iterative process. In particular, HYPOSTRE 2 shows convergence towards
a final solution, through a series of « damped » approximations.
The application of HYPOSTRE to about twenty earthquakes, which
have occured in the Strait of Messina and in the Gulf of Patti, demonstrates
a good convergence and a general stability of results.
Finally, comparison with analogous determinations — carried out by
other programs, with different crustal models and using a greater number
of recorded data — confirms the reliability of HYPOSTRE.
the hypocentral parameters of local earthquakes, even when they are recorded
by a small number of stations. These are the most frequent conditions
prevailing around the Strait of Messina.
The program employs the first arrivals of P and S waves, a model of
local crust consisting of four plane and parallel layers, and an algorithm
based on that of Geiger.
HYPOSTRE can determine simultaneously the four unknowns X, cp, h
and H (HYPOSTRE 4) and can calculate the epicentral coordinate separately
from focal depth (HYPOSTRE 2). In both cases the program follows
an iterative process. In particular, HYPOSTRE 2 shows convergence towards
a final solution, through a series of « damped » approximations.
The application of HYPOSTRE to about twenty earthquakes, which
have occured in the Strait of Messina and in the Gulf of Patti, demonstrates
a good convergence and a general stability of results.
Finally, comparison with analogous determinations — carried out by
other programs, with different crustal models and using a greater number
of recorded data — confirms the reliability of HYPOSTRE.
Article Details
How to Cite
BOTTARI, A. and NERI, G. (1980) “On locating local earthquakes at the Messina Strait network”, Annals of Geophysics, 33(1), pp. 281–296. doi: 10.4401/ag-4709.
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