ISSN:
1420-9136
Keywords:
Objective classification algorithm
;
local lithospheric stress distribution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Geosciences
,
Physics
Notes:
Abstract Classification of populations of focal mechanisms are commonly used as a step in retrieving states of stress in the lithosphere. Although such classifications are usually made according to subjective criteria, an objective one based on a classification algorithm is presented. The procedure is based on two steps. First, each mechanism is characterized by the components of its principal tensional and compressional axes and then objectively classified accordingly. Second, each mechanism is characterized by its geographic coordinates (latitude and longitude) after which each group obtained in the first step is divided into new groups according to geographic coordinates. The classification algorithm, together with a standard inversion algorithm, is applied to data from aftershocks belonging to the Irpinia (southern Italy) Earthquake of November 23, 1980. A few incompatible groups of focal mechanisms obtained by the classification algorithm show a spatial overlap. Nevertheless, the new methodology allows us to present a more accurate description of a local state of stress for an aftershock area than the stress pattern obtained from subjective classifications. The new stress pattern is compared with principal stress axes deduced from the main event and two local states of stress deduced previously from the aftershock mechanisms.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00878897
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