Earthquakes in a fault system embedded in an elastic body subject to increasing shear stress

Caputo, M. and Della Monica, G. and Fattori Speranza, F. and Reseda, S. and Sgrigna, V. (2000) Earthquakes in a fault system embedded in an elastic body subject to increasing shear stress. Il nuovo cimento C, 23 C (3). pp. 293-314. ISSN 1826-9885

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We consider the faults of an elastic body subject to an increasing stress and the stress field generated by slip on a fault. The slip along the fault releases the stress component parallel to the slip, but the component normal to the fault is not released and increases in time at the same rate as the shear affecting the body. The effect is an increase of the value of the force necessary to cause the subsequent slip; and, if the shear increases linearly, it causes an increase of the time intervals between the earthquakes on the fault, that is between the stress drop p and the slip s. The density distribution of p in a given time interval is computed; it is found that rigorously it is not a power law although it is a decreasing function of p. It is also seen that, as in the cases in which it was assumed that the component of the stress field locking the fault, after each earthquake, in the time interval to the next earthquake, would be anelastically released, the logarithm of the density distribution of the moments of the earthquakes is a linear function of log (M0 ) and a linear function of M in any time interval; M0 and M being the scalar seismic moment and the magnitude, respectively. Conditions for the existence of these linear relationships are discussed finding that a sufficient condition, when the range of p is not exceptionally large, is that the density distribution of p be of the type log (p), which includes the case when it is independent of the fault linear size l. The Gutenberg-Richter frequency-magnitude relationship and the conditions to obtain aftershocks and seismic swarms generated by this model are presented and discussed. In order to obtain the observed density distribution of earthquakes one or several hypotheses can be done: 1) the stress locking the faults, between successive earthquakes of the same fault, is released anelastically; 2) the density distribution of the sizes of the faults is such as to cause the logarithm of the density distribution of log (M0) and of M to be linear; 3) the density distribution of log M0 (M) is linear and the linearity factor is related to the density distribution of the stress drop and not to that of the linear dimensions of the faults.

Item Type: Article
Uncontrolled Keywords: Seismology; Earth’s interior structure and properties
Subjects: 500 Scienze naturali e Matematica > 550 Scienze della Terra > 551 Geologia, Idrologia, Meteorologia > 551.2 Vulcani, terremoti, acque termali e gas > 551.22 Terremoti (Classificare qui la Sismologia) (Classificare le onde di maremoto in 551.463)
Depositing User: Marina Spanti
Date Deposited: 09 Mar 2020 14:59
Last Modified: 09 Mar 2020 14:59

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