Based on results obtained from experiments on clay models, it appeared possible to establish main regularities in the evolution of normal and strike-slip zones which structures are formed heterogeneously in time and space. The spatial heterogeneity is reflected in the regular pattern of the fault zone structure due to the fact that sectors of two different types are length-wisely alternating in the fault zone. Within sectors of Type 1, the main fault forms rapidly. Sectors of Type 2 are characterized by the long-term evolution of the pattern, significant width and high densities of fractures; in final development phases, they are represented by relay structures. The temporal heterogeneity is manifested by stages and sub-stages in the development of the fracture network, which are closely interrelated. Each of the three main stages is associated with specific deformational behaviour of the medium and a particular type of the fracture pattern, as suggested by results of our tectonophysical modelling of fracturing. The model is presented in the article; it is supported by data on natural normal and strikeslip faults.

The article describes a method yielding approximate analytical solutions under the theory of elasticity for a set of interacting arbitrarily spaced shear fractures. Accurate analytical solutions of this problem are now available only for the simplest individual cases, such as a single fracture or two collinear fractures. A large amount of computation is required to yield a numerical solution for a case considering arbitrary numbers and locations of fractures, while this problem has important practical applications, such as assessment of the state of stress in seismically active regions, forecasts of secondary destruction impacts near systems of large faults, studies of reservoir properties of the territories comprising oil and gas provinces.

In this study, an approximate estimation is obtained with the following simplification assumptions: (1) functions showing shear of fractures’ borders are determined similar to the shear function for a single fracture, and (2) boundary conditions for the fractures are specified in the integrated form as mean values along each fracture. Upon simplification, the solution is obtained through the system of linear algebraic equations for unknown values of tangential stress drop. With this approach, the accuracy of approximate solutions is consistent with the accuracy of the available data on real fractures.

The reviewed examples of estimations show that the resultant stress field is dependent on the number, size and location of fractures and the sequence of displacements of the fractures’ borders.

The article provides a brief review of the history of tectonophysical meetings in the former Soviet Union and Russia. This information is published on the eve of the Third Tectonophysical Conference convened by the Institute of Physics of the Earth in October 2012.

The Shanxi tectonic belt is a historically earthquakeabundant area. For the majority of strong earthquakes in this area, the distribution of earthquake foci was controlled by the N–S oriented local structures on the tectonic belt. Studies of the present stress state of the Shanxi tectonic belt can contribute to the understanding of the relationship between strong earthquakes’ occurrence and their structural distribution and also facilitate assessments of regional seismic danger and determination of the regions wherein strong earthquakes may occur in future. Using the Cataclastic Analysis Method (CAM), we performed stress inversion based on the focal mechanism data of earthquakes which took place in the Shanxi tectonic belt from 1967 to 2010. Our results show that orientations of the maximum principal compressive stress axis of the Shanxi tectonic belt might have been variable before and after the 2001 Kunlun MS=8.1 strong earthquake, with two different superior trends of the NW–SE and NE–SW orientation in different periods. When the maximum principal compressive stress axis is oriented in the NE–SW direction, the pattern of the space distribution of the seismic events in the Shanxi tectonic belt shows a trend of their concentration in the N–S oriented tectonic segments. At the same time, the stress state is registered as horizontal shearing and horizontal extension in the N–S and NE–SW oriented local segments in turn. When the maximum principal compressive stress axis is NW–SE oriented, the stress state of the N–S and NE–SW oriented tectonic segments is primarily registered as horizontal shearing. Estimations of plunges of stress axes show that seismicity in the Shanxi belt  corresponds primarily to the activity of lowangle faults, and highangle stress sites are located in the NE–SW oriented extensional tectonic segments of the Shanxi belt. This indicates that the stress change of the Shanxi belt is caused by adjustment of the regional stress field, rather than by the diverse seismic activities.

Local rock dislocations and shifts, which occur due to strong seismic impacts, are studied. Natural cases under review include displacements that occurred after strong earthquakes in the 20th century and paleoseismic dislocations revealed by the authors in the crustal rocks in the south-eastern (Russian) part of the Fennoscandia shield. The major goal of the study was to determine parameters of the paleoseismic events in terms of intensity, I, and magnitude, M. Two independent options were used: (1) estimation with reference to similar cases in the instrumental measurements period and to the currently applied scaling systems, and (2) introduction of physical characteristics of disturbances of particular types and habitus and fixed values of displacements of the rock blocks. Numerous local disturbances of the rock massifs with significant rock shifts were systematically reviewed as a set of standard models. Values of mass velocities of seismic impacts (peak ground velocities, PGV), which were needed for initiation of the revealed dislocations, were estimated. In many cases, PGV values were above 1 m/sec, i.e. considerably higher than values conventionally accepted (for ground conditions). For clarifications, data on strong movements and explosions were used, and the whole set of data was found reasonably consistent. It was concluded that the cases with PGV>1 m/sec corresponded to focal areas of earthquakes with M>6 (mainly in the deglaciation period). A graphical chart is proposed for estimation of magnitudes and hypocentral distances of initiating earthquakes in case of maximum PGV within a range from 0.01 to 5.00 m/sec. Based on the graphical chart, parameters are estimated for earthquakes that might have caused the dislocations observed on the main sites of the region under study.

Analysis of data from permanent GPS observation stations located in tectonically active regions provides for direct observation of deformation processes of the earth's surface which result from elastic interaction of the lithospheric plates and also occur when accumulated stresses are released by seismic events and postseismic processes.

This article describes the methodology of applying the regression analysis of time series of data from GPS-stations for identification of individual components of the stations’ displacements caused by the influence of various deformation processes. Modelling of the stations’ displacements caused only by deformations of the marginal zone, wherein the lithospheric plates interact, allows us to study variations of the steady-state deformation in the marginal zone.

he proposed methodology is applied to studies of variations of fields of cumulative surface displacements, surface displacement velocity and maximum shear strain velocity which are determined from the GPS data recorded prior to the Parkfield earthquake of 28 September 2004 (Mw=6.0).

Combined analysis of the variations of the above-mentioned fields shows that measurable anomalies of the elastic deformation of the transform fault’s edge took place prior to the seismic event of 28 September 2004, and such anomalies were coincident in space and time with the focal area of the future seismic event.

In the Earth’s regions with cold climate, cryovolcanism is widespread. This phenomena is manifested as eruptions of material due to freezing of closed-type or open-type water-bearing systems which is accompanied by generation of effusive topographic forms, such as «pingo». The Patom cone is a typical structure created by cryovolcanism in fractured bedrocks
of the Proterozoic age. The cone was shaped a result of the long-term, possibly multistage freezing of the hydrogeological structure during continuous and complicated phase of cryo- and speleo-genesis. The ice-saturated breccia containing limestone, sandstone and shale, which composed the cone, was subject to slow spreading due to its plastic properties; the top of the mound developed into a subsidence cone bordered by ring-shaped ramparts and a knoll in the middle, while the
longitudinal profile took on an asymmetric form. The absence of soil and vegetation cover on the surface of the cone, and a relatively weak degree of weathering of the rudaceous deposits bear no evidence that the geological object is young. The question as to the age of the cone is still open.