Operation of vibration source of an unbalance type with liquid-filled internal working chamber

Equipment for increasing water inflow to the well is proposed, which affects the aquifer by seismic vibrations. The method is based on accelerating the filtration process in soils, exposed to vibration. The equipment can work in conjunction with a submersible pump and has the ability to pump liquid through the working chamber of the generator. Generators can be combined into a group and driven by one electric motor to increase the efficiency of vibration treatment. This method is built into the existing technology of dewatering and pits drainage. The dynamics of the vibration source operation of an unbalance type with a liquid-filled inner chamber was studied in laboratory conditions, on a test. The vibration source was attached to the stand frame and was in a vertical position coaxially with the electric drive, thereby simulating its location in the well. The unbalance was unwound by an electric drive with a rotation frequency of 10 to 50 Hz in 5 Hz steps and seismic vibrations, generated by a vibration source, were recorded. Based on the experiments’ results, the amplitude-frequency characteristics of an unbalanced vibration source in the low-frequency range with a dry and liquid-filled inner chamber were obtained. In order to prevent the bearing assemblies from jamming, their heating was monitored with a thermal imager and temperature sensors.

Seismic response of various sites of the territory of Kyiv to seismic loads

The research presented in the work aims to assess the seismic response of three different taxonometric sites, identified by the method of engineering and geological analogies within the territory of Kyiv, to seismic loads with different spectral content and peak amplitude from 0.01 g to 0.06 g. Assessment of the influence of local soil conditions on the intensity of earthquakes is an important task of earthquake-resistant design and construction. The soil layer at the base of the study site acts as a filter on seismic vibrations. It amplifies or attenuates the amplitude of the seismic wave propagating from the bedrock to the free surface. The paper considers the mechanisms of the possible amplification of seismic motions by various soil complexes and methods for calculating the seismic response to seismic loads of various intensities. As an analytical tool for analyzing the response of the taxonometric areas to seismic vibrations (seismic response), an equivalent linear analysis was used, which is comprehensively studied and widely used in engineering seismology. For the selected sites, models of soil strata were built, and graphs of changes with depth of peak shear strain and peak ground acceleration (PGA) were calculated, as well as predicted (expected with a given probability of non-exceeding) amplitude Fourier spectra of seismic motions in the upper layer and the response spectra of single oscillators with 5 % attenuation to seismic effects with a maximum amplitude from 0.01 g to 0.06 g. A comparative analysis of the change in the value of these parameters in individual sections of Kyiv is presented. It is shown that to assess the potential hazard from seismic ground motions during earthquakes, it is necessary to use the maximum number of design parameters that characterize the seismic hazard of specific areas and which are used to determine the seismic resistance of buildings and structures. The most complete seismic hazard for calculating the seismic stability of objects is set by the full vector of seismic motions deployed in time: calculated accelerograms, seismograms and velocigrams. The presented calculation results are planned to be used in solving methodological and practical problems of earthquake protection, which can be realized in different parts of the territory of Kyiv.

The shallow structure of Mars at the InSight landing site from inversion of ambient vibrations

Orbital and surface observations can shed light on the internal structure of Mars. NASA’s InSight mission allows mapping the shallow subsurface of Elysium Planitia using seismic data. In this work, we apply a classical seismological technique of inverting Rayleigh wave ellipticity curves extracted from ambient seismic vibrations to resolve, for the first time on Mars, the shallow subsurface to around 200 m depth. While our seismic velocity model is largely consistent with the expected layered subsurface consisting of a thin regolith layer above stacks of lava flows, we find a seismic low-velocity zone at about 30 to 75 m depth that we interpret as a sedimentary layer sandwiched somewhere within the underlying Hesperian and Amazonian aged basalt layers. A prominent amplitude peak observed in the seismic data at 2.4 Hz is interpreted as an Airy phase related to surface wave energy trapped in this local low-velocity channel.

The use of the vulnerability factor in the study of vibration signals on the soil surface from the movement of subway electric trains

Microseismic vibrations of the upper part of the soil strata occur continuously under the influence of endogenous and exogenous processes of both natural and artificial origin. Micro-oscillations of technogenic nature are especially characteristic of densely built-up urban areas. The practice of monitoring seismological monitoring observations shows that under such conditions it is possible to observe various types of microseismic vibrations, including elastic vibration signals in the frequency range of 1—100 Hz, generated by passing subway trains. In the calculations of the seismic stability of the designed structures, special attention is paid to the resonance characteristics of the upper part of the soil strata, which at certain frequencies can significantly enhance seismic vibrations, for example, from external vibrations sources. By traditional methods, the characteristics of resonant oscillations and their accounting are carried out, as a rule, with an insufficient degree of reliability and completeness, as a result of whichand so they are usually used as auxiliary ones. In this paper, a methodological complex is considered using modern methods for measuring and processing microseismic signals in order to identify areas with maximum amplitudes of response to external elastic influences in the study area for construction and take them into account in the future in design and construction. The study of vibroseismic noises formed on the surface of the soil layer, for example, by passing subway trains, allows one to estimate the amplitude-frequency properties of these soils, and the spectral ratio of horizontal displacements of soils to vertical H/V and the derivative of these ratios — the coefficient of vulnerability of the Ky — provide a confident selection of weakened zones that are subject to the greatest impact of external elastic vibrations.

Recording and on-line analysis of the earthquakes at the National center of seismological data

The research is dedicated to statistical analysis of such a powerful natural phenomenon as an earthquake and to the problems of monitoring the seismicity in the territory of Ukraine directly. According to evidences of century-old data, annual number and the strengths of earthquakes differ, however its growth is observed definitively. Such a trend needs more attentive attitude to manifestations of seismic activity and its results even within the platform parts of the territory of Ukraine. Examples of registering earthquakes observations of different intensity and remoteness by Ukrainian observation net have been made. Special consideration at the National center of seismological data has been given to seismic vibrations which appear and are fixed in the areas bordering Ukraine and within its territories directly. Essential background for elaboration and successful practical usage of the medium-term and short-term methods of forecasting the approaching seismic catastrophe or dangerous development of the seismic process which has begun are observation and on-line processing of the earthquakes at the National center of seismological data with successive producing bulletins and catalogues.

Foreword Special issue Empowering communities for non-structural seismic risk mitigation: the central role of communication

This special issue of “Annals of Geophysics” concerns the dissemination of knowledge on the prevention of damage mainly due to non-structural elements during earthquakes and its practical application at houses, schools and offices by common citizens, companies and institutions. The seismic capacity of buildings and other civil engineering structures and infrastructures are object of regulations for design and construction, and in some cases also the design, fabrication and mounting of electrical and mechanical equipments. Consequently, even in strong earthquakes many collapses of buildings and infrastructures are avoided. However, with few exceptions, design procedures do not aim at avoiding seismic vibrations from being transferred to the structures, but enable the structures to resist to the effects of those vibrations

Noise matters: elephants show risk-avoidance behaviour in response to human-generated seismic cues

African elephants ( Loxodonta africana ) use many sensory modes to gather information about their environment, including the detection of seismic, or ground-based, vibrations. Seismic information is known to include elephant-generated signals, but also potentially encompasses biotic cues that are commonly referred to as ‘noise’. To investigate seismic information transfer in elephants beyond communication, here we tested the hypothesis that wild elephants detect and discriminate between seismic vibrations that differ in their noise types, whether elephant- or human-generated. We played three types of seismic vibrations to elephants: seismic recordings of elephants (elephant-generated), white noise (human-generated) and a combined track (elephant- and human-generated). We found evidence of both detection of seismic noise and discrimination between the two treatments containing human-generated noise. In particular, we found evidence of retreat behaviour, where seismic tracks with human-generated noise caused elephants to move further away from the trial location. We conclude that seismic noise are cues that contain biologically relevant information for elephants that they can associate with risk. This expands our understanding of how elephants use seismic information, with implications for elephant sensory ecology and conservation management.

Method of registration of seismic waves

This article provides an overview of the methodology for recording seismic waves. The main types of seismic vibrations and methods of their study have been determined.