http://science.sciencemag.org/content/sci/181/4102/803.full.pdf

Earthquake Prediction: A Physical Basis

During the earthquake preparation a zone of cracked rocks is formed in the region of a future earthquake focal zone under the influence of tectonic stresses. In the study of the surrounding medium this region may be considered as a solid inclusion with altered moduli. The inclusion appearance causes a redistribution of the stresses accompanied by corresponding deformations. This paper deals with the study of deformations at the Earth's surface, resulting from the appearance of a soft inclusion. The Appendix contains an approximate solution of the problem for a soft elastic inclusion in an elastic half-space. It is assumed that the moduli of the inclusion differ slightly from those of the surrounding medium (by no more than 30%). The solution permits us to calculate the deformations at the Earth's surface for the inclusion with an arbitrary heterogeneity and anisotropy. The problem is solved by the small perturbation method. The calculation is made for a special case of a homogeneous isotropic inclusion where only the shear modulus decreases. The shear stresses act at infinity. The equations are deduced for the estimation of deformations and tilts at the Earth's surface as a function of the magnitude of the preparing earthquake and the distance from the epicentre. Comparison has shown a satisfactory agreement between the theoretical and field results. Let us assume that the zone of effective manifestation of the precursor deformations is a circle with the centre in the epicentre of the preparing earthquake. The radius of this circle called ‘strain radius’ may be calculated from the equation
 
$$\rho = 10^{0.43M} km,$$

 where M is the magnitude. It was shown that the precursors of other physical nature fall into this circle.

Estimation of the size of earthquake preparation zones

SUMMARY Earthquake prediction research has been conducted for over 100 years with no obvious successes. Claims of breakthroughs have failed to withstand scrutiny. Extensive searches have failed to find reliable precursors. Theoretical work suggests that faulting is a non-linear process which is highly sensitive to unmeasurably fine details of the state of the Earth in a large volume, not just in the immediate vicinity of the hypocentre. Any small earthquake thus has some probability of cascading into a large event. Reliable issuing of alarms of imminent large earthquakes appears to be effectively impossible. Key word: Earthquake prediction.

Earthquake prediction: a critical review

Electroreceptors are sense organs by which animals obtain biologically relevant information from natural electric fields (Machin, 1962; Kalmijn, 1971; cf. Bennett’s reviews, 1971b and c, and Bullock’s Introduction to the present Volume, Chapter 1). Therefore, however suggestive the electrical characteristics of a sense organ may be, the final justification for using the term electroreceptor depends upon the role that the sense organ in question plays in the animal’s life. To establish and analyze this role, a basic knowledge of the natural electric fields and the information they provide is an essential prerequisite. Whether the information is of biological significance to electrosensitive animals must be determined by appropriate behavioral experiments.

The Detection of Electric Fields from Inanimate and Animate Sources Other Than Electric Organs

https://www.leif.org/EOS/Earthquake-Precursors.pdf

L.A. Latynina

Papers

The processes preceding strong earthquakes in some regions of middle Asia

Strain processes before the Spitak earthquake

On certain anomalies in the variations of crustal strains before strong earthquakes

On horizontal deformations at faults recorded by extensometers