ABSTRACT
In this review paper, we discuss the nature of an apparent link between heterogeneities associated with geological anomalies hidden from direct observation, detected when they are analysed remotely from various distances-including borehole conditions as well as aero imaging. Here, the main emphasis is placed on geological and geophysical features represented by spatially distributed signals measured along drilled well or along predefined spatial routes. In the common practice of indirect measurements of parameters of seismically active regions, there exist certain observations on correlations in the vicinity of structural and geological anomalies, repeated patterns in the representation of correlation functions and corresponding classification in multidimensional statistical methods. Underlying natural physical processes, which determine the structure of the primary anomalous environment, are of interest. Physical analogies, based on the mathematical modelling and generalization of empirical data, may suggest that such a process may be linked to wave phenomena on a geological scale. Applications include analysis of anomalies associated with non-potential fields, mapping of geodynamic zones and seismic microzoning; reconstruction of the geostructural vertical section of the mountainous regions. This article is part of the theme issue 'Wave generation and transmission in multi-scale complex media and structured metamaterials (part 2)'.
ABSTRACT
A new approach to seismic analysis has been introduced and demonstrated for a sequence of recent seismic events recorded in the Blackpool region of Lancashire, UK. The seismic activity, induced by an industrial hydraulic fracturing at a depth exceeding 2 km, had the extent of registered surface elastic vibrations reaching a distance exceeding 15 km. The analysis is based on the study of elastic fields, three-dimensional extrapolations of the landscape and the novel reconstruction of a three-dimensional digital model of seismic map boundaries and vertical profiles. The verification of the proposed approach is carried out via the comparison with published data of the Blackpool seismic events, combined with the new spectral analysis linked to the identified regions of seismic activity. The latter was accompanied by a finite-element simulation of vibrations for an elastic layer of variable thickness, approximating the test region. The analysis and numerical modelling have demonstrated consistency with the dynamic nature of structural stratification of the geological systems, and in addition, the predictive nature of the modelling work was demonstrated by the comparison of the model eigenmodes with the published parameters of registered earthquakes in the Blackpool area. This article is part of the theme issue 'Wave generation and transmission in multi-scale complex media and structured metamaterials (part 1)'.
