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The short-term effect of heavy rainfall on gPhone gravimeter observation at Zhengzhou Seismic Station is investigated. According to the observation data during Jul. 17–20, 2021, the corrected gravity residual reflects the gravimetric response caused by heavy rainfall. The observed gravity change is dominated by the local effect considering topographic effect on gravity. The deduced water depth near the observation station is about 300 mm. [ABSTRACT FROM AUTHOR]

A dynamic gravimeter with an atomic interferometer (AI) can perform absolute gravity measurements with high precision. AI-based dynamic gravity measurement is a type of joint measurement that uses an AI sensor and a classical accelerometer. The coupling of the two sensors may degrade the measurement precision. In this study, we analyzed the cross-coupling effect and introduced a recovery vector to suppress this effect. We improved the phase noise of the interference fringe by a factor of 1.9 by performing marine gravity measurements using an AI-based gravimeter and optimizing the recovery vector. Marine gravity measurements were performed, and high gravity measurement precision was achieved. The external and inner coincidence accuracies of the gravity measurement were ±0.42 mGal and ±0.46 mGal after optimizing the cross-coupling effect, which was improved by factors of 4.18 and 4.21 compared to the cases without optimization. [ABSTRACT FROM AUTHOR]

In the article the parametric oscillations of an unreformed disk located in a contactless electromagnetic suspension with an electrostatic loop of the effective control stiffness were investigated analytically. The analytical expressions for the transition curves of the stationary position of the levitated object were obtained based on the asymptotical method of nonlinear dynamics for the areas of the main and secondary parametric resonances. The system parameters were estimated for which the contactless suspension with quasi-zero electromagnetic stiffness is asymptotically stable. [ABSTRACT FROM AUTHOR]

The aim of this work is to create a new type of gravimeter that can function effectively in the challenging conditions of space, specifically on the surfaces of planets and moons. The proposed device, called a diamagnetically stabilized magnetically levitated gravimeter (DSMLG), uses magnetic forces to balance a test mass against the force of gravity, allowing for accurate measurements. A diamagnetically stabilized levitation structure comprises a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet levitates between two diamagnetic plates without the need for external energy input due to the interaction between the magnetic forces of the floating magnet and the stabilizing force of the diamagnetic material. This structure allows for stable levitation of the floating magnet without requiring additional energy. The goal is to design a gravimeter that is lightweight, requires minimal power, can withstand extreme temperatures and shocks, and has a low data rate. The authors envision this gravimeter being used on various robotic spacecraft, such as landers and rovers, to study the interiors of rocky and icy celestial bodies. This paper reports on the results of a finite element model analysis of the DSMLG and the strength of the resulting diamagnetic spring. The findings contribute to the understanding of the levitation characteristics of diamagnetically stabilized structures and provide valuable insights for their practical applications, including in the development of the proposed DSMLG. [ABSTRACT FROM AUTHOR]

Abstract This report contains terrestrial absolute gravity measurements performed near the village of Kulusuk in southeast Greenland. It represents an exceptionally long time series of nearly two decades. The measurements began in July 1996 until July 2015. The station is located a few meters beside a permanent GNSS station. The final gravity values (g‐values), more precisely the accelerations due to gravity, are listed along their associated uncertainties. A description of the station, a short explanation on the absolute gravimeter, and the data processing are presented.

This report contains terrestrial absolute gravity measurements performed near the village of Kulusuk in southeast Greenland. It represents an exceptionally long time series of nearly two decades. The measurements began in July 1996 until July 2015. The station is located a few meters beside a permanent GNSS station. The final gravity values (g‐values), more precisely the accelerations due to gravity, are listed along their associated uncertainties. A description of the station, a short explanation on the absolute gravimeter, and the data processing are presented. [ABSTRACT FROM AUTHOR]

The article discusses the principle of operation and the main components of jet-drop optical measuring systems (JDOMS) based on the pendant drop method for monitoring electric field strength (EFS), magnetic field (MFS) and gravitational field (GFS). To make a pendant drop sensitive to electric or magnetic fields, it is proposed to charge it electrostatically or to create it from a magnetic fluid, and its mass allows you to feel changes in the gravitational field. The use of magnetic fluids as the basis of a pendant drop is the most multifunctional for measurements of EFS, MFS and GFS. The implementation of the zero measurement method using a pendant drop as a comparison device, a null organ that perceives the difference in the effects of the measured and reference field(s) at the level of quasi-zero three-coordinate displacements, is considered. They are measured by high-precision optical measurement methods. Different variants of modern optical measurement systems are analyzed.

Underwater gravity-assisted navigation is typically employed by submarines as a navigation method when external navigation information is not easily available, which necessitates the acquisition of gravity information through autonomous measurement. However, underwater gravity measurement research currently relies heavily on high-precision external navigation information, such as acoustic positioning, and lacks autonomy. Therefore, there is a contradiction between the existing underwater gravity measurement technology and the underwater gravity-assisted navigation application scenario. To solve this problem, a real-time, autonomous gravity measurement method specifically designed for underwater gravity-assisted navigation is proposed in this study. The proposed method achieves real-time, autonomous underwater gravity measurement with mGal-level precision by integrating classical gravity measurement principles, which involves a gravimeter, an electromagnetic log (EML), and a depth gauge (DG). To evaluate the proposed method’s effectiveness, a semi-physical simulation was conducted through vehicle testing. The experimental results demonstrated that the proposed method achieved a precision of 1.01 mGal at 0.0033 Hz within the repeated measuring line.

A dynamic gravimeter with an atomic interferometer (AI) can perform absolute gravity measurements with high precision. AI-based dynamic gravity measurement is a type of joint measurement that uses an AI sensor and a classical accelerometer. The coupling of the two sensors may degrade the measurement precision. In this study, we analyzed the cross-coupling effect and introduced a recovery vector to suppress this effect. We improved the phase noise of the interference fringe by a factor of 1.9 by performing marine gravity measurements using an AI-based gravimeter and optimizing the recovery vector. Marine gravity measurements were performed, and high gravity measurement precision was achieved. The external and inner coincidence accuracies of the gravity measurement were ±0.42 mGal and ±0.46 mGal after optimizing the cross-coupling effect, which was improved by factors of 4.18 and 4.21 compared to the cases without optimization.

The aim of this work is to create a new type of gravimeter that can function effectively in the challenging conditions of space, specifically on the surfaces of planets and moons. The proposed device, called a diamagnetically stabilized magnetically levitated gravimeter (DSMLG), uses magnetic forces to balance a test mass against the force of gravity, allowing for accurate measurements. A diamagnetically stabilized levitation structure comprises a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet levitates between two diamagnetic plates without the need for external energy input due to the interaction between the magnetic forces of the floating magnet and the stabilizing force of the diamagnetic material. This structure allows for stable levitation of the floating magnet without requiring additional energy. The goal is to design a gravimeter that is lightweight, requires minimal power, can withstand extreme temperatures and shocks, and has a low data rate. The authors envision this gravimeter being used on various robotic spacecraft, such as landers and rovers, to study the interiors of rocky and icy celestial bodies. This paper reports on the results of a finite element model analysis of the DSMLG and the strength of the resulting diamagnetic spring. The findings contribute to the understanding of the levitation characteristics of diamagnetically stabilized structures and provide valuable insights for their practical applications, including in the development of the proposed DSMLG.

Compare with the airborne and satellite-borne gravity measurements, terrestrial gravity measurements (TGMs) are closer to the sources of mass change and have relatively higher accuracy. The static anomalies and dynamic changes derived from TGMs have been widely used to study various geodynamic problems. Many high-precision gravity products using TGMs have become available since 21 century because of the development of modern observation techniques (especially those in absolute gravimetry) and the terrestrial network. Much of the progress of geodesy and geophysics has come from these products. In this paper, we briefly summarize the recent progress in geodesy and geophysics using high-precision TGMs during the last decade or so. The first group of applications adopts the gravity anomalies from TGMs, which includes constructing gravity field and geoid models, establishing crustal models, computing Moho undulations, and estimating the effective elastic thickness of the lithosphere. The second group of applications adopts the time-varying gravity changes from TGMs, which includes constructing time-varying gravity field models, detecting weak dynamic signals, estimating crustal tectonic deformation rates, and analyzing possible correlations with volcanic and seismic processes. We also discuss the next opportunities for ground gravimetry. Our findings could benefit the construction and development of the gravity observation system in the Chinese Mainland.

As discussed in the previous part of this review article, remote sensing (RS) creates unprecedented opportunities by providing a variety of systems with different characteristics to study and monitor oceans. Part 1 of this review article was dedicated to reviewing passive RS systems and their main applications in the ocean. Here, in part 2, seven active RS systems, including scatterometers, altimeters, gravimeters, synthetic aperture radar, light detection and ranging, sound navigation and ranging, high-frequency radars are comprehensively reviewed. For consistency, this part is structured similarly to part 1. The aforementioned systems, along with their characteristics and primary applications, are introduced in separate sections. This review article provides useful information to all students and researchers who are interested in the oceanographic applications of active RS systems.

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We presented a concept of a modern gravimetric-geodetic survey, the data processing and analysis of gravimetric observations and, ultimately, a new gravimetric map of the territory of Lithuania. In this connection. we outlined the applied algorithms for calculating free-air gravity anomalies and Bouguer anomalies, as well as assessed their accuracy and the accuracies of other parameters. The following accuracies were obtained: 0.021 mGal for uncertainties ofgravity acceleration according to differences detected at control points, 0.025 iii for coordinates, 0.015 m for ellipsoidal heights, 0.073 mGal for Bouguer anomalies, and 0.326 inGal for interpolated Bouguer anomalies. We further described the content of the gravimetric map. The map shows gravity measurement points together with their recorded value of Bouguer anomaly. Isoanomalies of gravity acceleration are drawn every 2 inGal. The scale of the map is 1:200,000. The printed version ofthe gravimetric map of the territory of Lithuania consists of 15 pages (50 x 50 cm). [ABSTRACT FROM AUTHOR]

The physical properties of tidal gravimetric instruments allow recording, not only tidal effects, but also waves generated by earthquakes. Three gravimetric stations with determined transfer functions and co-located seismic stations from the observatories in Western and Central Europe were selected for analysis. The observatories are equipped with almost all types of sensors available on the market, which allow for thorough analysis of earthquake recordings in the period range of 10–1000 s. In total, over 10,000 traces of worldwide earthquakes were investigated. The saturation levels of gravimeters as well as a correlation between the gravimetric and seismometric signals of an earthquake were carefully analysed. A simple processing scheme of gravimetric signal of earthquakes was adopted thanks to the probabilistic power spectral density analysis of continuous recordings. The detail analysis of transfer function of gravimeters allowed to define a period range when a sensitivity coefficient (calibration factor) and a time lag value only can be used to properly describe the properties of instruments. What’s more, it has been shown based on the calculated group-velocity dispersion curves of fundamental mode of Rayleigh waves, that the Earth’s mantle structure can be determined for greater depths from the recording of tidal gravimeters than from typical broad-band seismometers. [ABSTRACT FROM AUTHOR]

The CG6 is an automated gravity meter that has a worldwide measurement range of over 8000 mGals and a reading resolution of 0.0001 mGal. Some factors that may influence the gravity readings are corrected by the instrument's software. In this paper, the effects of the ambient temperature and humidity changes on the CG-6's gravity measurements were investigated with the aim of reducing the uncertainty which remains in gravity measurements in microgal level, and giving recommendations for more accurate results. A controlled heating experiment was used to determine the impact of ambient temperature on gravity and 12 hours of continuous gravity observations were used to identify the impact of humidity on gravity measurements. It was observed that the sensor temperature and the gravity reading were highly correlated with the ambient temperature. The linear correlation with R2 > 0.94 and R2 > 0.90 were found for the corrected gravity reading and the residual sensor temperature variations respectively with the ambient temperature when heating. It was demonstrated that the calculated ambient temperature correction, −0.0011 mGal/oC, is more stable than the correction given by the instrument in terms of standard deviation though the impact of humidity on gravity reading was not clear. [ABSTRACT FROM AUTHOR]

The paper describes an improved technology of quartz elastic system manufacturing for the gravimeters of Chekan series; its purpose is to automate the manufacturing processes of the elastic system elements to improve the work quality and performance. The elastic system manufactured using this technology has been tested on a bench and in field, and the results confirmed its compliance with the requirements set for the sensitive elements of modern mobile gravimeters. [ABSTRACT FROM AUTHOR]

Knowledge of the spatio-temporal changes in the characteristics and distribution of subsurface fluids is key to properly addressing important societal issues, including: sustainable management of energy resources (e.g., hydrocarbons and geothermal energy), management of water resources, and assessment of hazard (e.g., volcanic eruptions). Gravimetry is highly attractive because it can detect changes in subsurface mass, thus providing a window into processes that involve deep fluids. However, high cost and operating features associated with current instrumentation seriously limits the practical field use of this geophysical method. The NEWTON-g project proposes a radical change of paradigm for gravimetry through the development of a field-compatible measuring system (the gravity imager), able to real-time monitor the evolution of the subsurface mass changes. This system includes an array of low-costs microelectromechanical systems-based relative gravimeters, anchored on an absolute quantum gravimeter. It will provide imaging of gravity changes, associated with variations in subsurface fluid properties, with unparalleled spatio-temporal resolution. During the final ∼2 years of NEWTON-g, the gravity imager will be field tested in the summit of Mt. Etna volcano (Italy), where frequent gravity fluctuations, easy access to the active structures and the presence of a multiparameter monitoring system (including traditional gravimeters) ensure an excellent natural laboratory for testing the new tools. Insights from the gravity imager will be used to i) improve our knowledge of the cause-effect relationships between volcanic processes and gravity changes observable at the surface and ii) develop strategies to best incorporate the gravity data into hazards assessments and mitigation plans. A successful implementation of NEWTON-g will open new doors for geophysical exploration.

The paper addresses the systematic error of an inertial navigation system, caused by the discrepancy between the plumb line and the normal to the reference ellipsoid surface. The methods of this discrepancy estimation, and their use for correcting the output data of inertial navigation systems are studied. [ABSTRACT FROM AUTHOR]

Development of an accurate reservoir model and prediction of reservoir behaviour associated with geothermal exploitation using that model are fundamentally important for sustainable geothermal utilisation. Gravity observation for a few tens of days after a field-wide shut-in of geothermal wells potentially provides valuable constraints to improve reservoir models. We investigated the applicability of superconducting gravimeters (SGs) to short-term observations after shut-ins, as a first step towards the development of a method for reservoir model improvement using short-term gravity data. Results from a reservoir simulation of a shut-in at a geothermal field in Japan showed that gravity change at 20 days after the shut-in was 10 nm/s2. To detect such changes with SGs, locations of SG stations should be chosen to minimise noise sufficient to resolve the signal. Considering that field operations and traffic in geothermal fields can make SG data noisy, laboratory gravity measurements were carried out with a SG to investigate the influence of noise level on signal detection. Test masses, which produced a gravity change (7.7–9.0 nm/s2) comparable to the simulation result, were repeatedly placed and removed above the SG during both day and night times with different ambient noise levels. Test results showed that noise level greatly affected signal detection. The signal was only detected twice, under low-noise conditions with the standard deviations of 1.1 and 5.3 nm/s2. In addition, tests in which the SG was operated without a cryogenic refrigerator revealed that the absence of the refrigerator did not increase the noise level. Enhancing the portability of a SG by reducing its weight can make multi-location noise surveys feasible. Our method, of combining reservoir simulations and preliminary noise surveys, would enable successful SG observations to be made in relatively short periods after shut-ins, which would possibly contribute to the development of a method to obtain additional constraints to be used for reservoir model calibration. [ABSTRACT FROM AUTHOR]

The phenomenon of synchronous episodic increase in gravimetric noise at the stations distant by thousands of kilometers from each other is described. The comparison with microseismic noise suggests inertial rather than gravimetric origin of the recorded anomalies. The duration of anomalous enhancement in microvibrations ranges from a few hours to a few days. The nature of synchronous microvibrations involving significant segments of the Earth's lithosphere is unclear; the probable causes are discussed. The conducted analysis has shown that among the key factors responsible for the increase in the microseismic noise in the European part of Russia is the influence of marginal seas, in particular, the storm-generated microseisms. The allowance for this phenomenon is necessary in planning and conducting high-precision gravity surveys and long-term gravity observations. [ABSTRACT FROM AUTHOR]

Measuring gravity from an aircraft is essential in geodesy, geophysics and exploration. It fills a gap between satellite techniques which have a low spatial resolution and traditional ground measurements which can only be performed on ground in accessible areas. Today, only relative sensors are available for airborne gravimetry. This is a major drawback because of the calibration and drift estimation procedures which lead to important operational constraints and measurement errors. Here, we report an absolute airborne gravimeter based on atom interferometry. This instrument has been first tested on a motion simulator leading to gravity measurements noise of 0.3 mGal for 75 s filtering time constant. Then, we realized an airborne campaign across Iceland in April 2017. From repeated line and crossing points, we obtain gravity measurements with an estimated error between 1.7 and 3.9 mGal. The airborne measurements have also been compared to upward continued ground gravity data and show differences with a standard deviation ranging from 3.3 to 6.2 mGal and a mean value ranging from − 0.7 to − 1.9 mGal. [ABSTRACT FROM AUTHOR]

The paper presents the gravimeters for measuring the gravity from moving platforms, and the stages of their development at the Concern "Central Scientific Research Institute "Elektropribor" (hereinafter CSRI Elektropribor). Engineering solutions are described, due to which high accuracy of measurements has been achieved. The authors discuss popular applications of mobile gravimeters. [ABSTRACT FROM AUTHOR]

• Temperature compensation in gravimeters and accelerometers. • Multi-sensor and Machine Learning approaches. • Laboratory platform for training data generation. • Applicability to other measuring systems, such as magnetometers and gyroscopes. Temperature is a major source of inaccuracy in high-sensitivity accelerometers and gravimeters. Active thermal control systems require power and may not be ideal in some contexts such as airborne or spaceborne applications. We propose a solution that relies on multiple thermometers placed within the accelerometer to measure temperature and thermal gradient variations. Machine Learning algorithms are used to relate the temperatures to their effect on the accelerometer readings. However, obtaining labeled data for training these algorithms can be difficult. Therefore, we also developed a training platform capable of replicating temperature variations in a laboratory setting. Our experiments revealed that thermal gradients had a significant effect on accelerometer readings, emphasizing the importance of multiple thermometers. The proposed method was experimentally tested and revealed a great potential to be extended to other sources of inaccuracy as well as to other types of measuring systems, such as magnetometers or gyroscopes. [ABSTRACT FROM AUTHOR]

In this paper, an analysis of the spread of random extraneous low-frequency (50 Hz) vibrations excited in a gravimeter body is presented. Further, their influence on the gravimeter scale reference system is determined by applying the theory of covariance function. The data on the measurement of strength of random extraneous vibrations in fixed points excited in the gravimeter body were recorded on the time scale in the form of arrays using a three-axis accelerometer. High-frequency (2 and 20 kHz) noise vibrations were also used to modulate the gravimeter scale data. While processing the results of measuring the strength of random extraneous vibrations and the data arrays on the reference system, estimates of autocovariance and cross-covariance functions by changing the quantisation interval on the time scale were calculated. Software developed within the MATLAB 7 package was applied for the calculations. [ABSTRACT FROM AUTHOR]

Modern methods of studying the Earth's gravity field on a mobile base are discussed, among them aerogravimetric research. The features of creating a highly autonomous airborne gravimetric laboratory with a long flight duration for operations in remote territories and waters are described. The experience of creating an airborne laboratory based on AN-30D and AN-26BL aircraft is discussed in detail. The makeup of gravimetric and navigation equipment is substantiated; the need for installing additional thermal and vibration protection devices, backup power lines, and additional communication facilities is shown; and the device and operation of airborne gravimetric systems based on different principles of operation are considered. The aerogravimetric survey method and features of its implementation are discussed. The main provisions of the software packages for in situ and office processing of gravimetric and navigation information obtained both on board the aircraft and at GPS or GLONASS base (ground) stations are presented. Methods for taking into account corrections for aerogravimetric systems with different operating principles are discussed. [ABSTRACT FROM AUTHOR]

Calibration measurements of the Scintrex CG-5 gravimeter were conducted using absolute gravity stations of the Japan Gravity Standardization Net, to constrain the scale factor and its temporal changes. The calibration data were obtained from a total gravity interval of 1.4 Gal through six campaigns, conducted for over 5 years between years 2012 and 2017. The scale factors varied by 1500 ppm in a range from 0.9991 to 1.0006, according to station combinations of the six campaigns. The scale factor depends primarily on the gravity reading ranges: for similar gravity reading ranges, no significant differences in the estimated scale factors were recognised, even though station combinations and observed times are different. Therefore, the gravity readings can be corrected by introducing a gravity reading-dependent scale factor. Furthermore, even though the scale factor essentially depends on gravity readings and not on time, temporal changes were observed during repeated calibration measurements at the same station combinations. A long-term instrumental drift of the CG-5 gravimeter could explain this phenomenon. In conclusion, the calibration shifts recognised during repeated measurements were apparently caused by: (1) the scale factor dependence on the gravity reading ranges and (2) the shift of the gravity reading ranges due to the instrumental drift. [ABSTRACT FROM AUTHOR]

Aerogravimetric survey is a rapidly developing and promising method for studying the gravity field in remote regions of the Earth. However, its practical use involves difficulties. Thus, during flights, inertial interference occurs due to engine-induced vibration of the fuselage. Earlier, various options for antivibration designs were tested. During its annual aerogravimetric works, the Schmidt Institute of Physics of the Earth, Russian Academy of Sciences (IPE RAS), employs a quite efficient option, which, however, cannot be regarded as complete. For the first time, a high-frequency seismometer was used to evaluate the efficiency of a gravimeter antivibration system used in aerogravimetric operations. Vibration suppression was assessed in a wide frequency range. During experimental flights, a decrease in vibration noise was detected at a frequency of 2 Hz, which is relevant for gravimetric equipment. The experimental results confirm the adequacy of the applied antivibration equipment. The antivibration platform developed at IPE RAS significantly reduces vibrations affecting the GT-2M aerogravimetric system. The possibility of using the Baikal-ACN high-frequency seismometer in an unconventional field of application is demonstrated. [ABSTRACT FROM AUTHOR]

Software- and hardware-based methods of compensation for dynamic errors of the marine gravimeters caused by inertial accelerations are considered. The error due to the fluid damping of the gravimeter sensing element is analyzed and taken into account for the first time. Some results of gravity measurements that confirm the increase in gravimeter accuracy are presented. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The results of gravimetric investigations have a huge contribution in the studying of regional problems, especially in determining the tectonic structure of the investigated area, in the process of searching for all types of mineral resources, including the process of development of the ore deposit. Contemporary gravimetric tests with which the measurements can be performed in the hollows can also be conditionally applied to determine the porosity of the hydrocarbon collector. It should be noticed that any gravity anomaly is the sum of the gravitational influences of all the surpluses and deficits on the mass, which with their presence change the normal gravitational field of the Earth at the place of measurement. The aforementioned fact implies that all present influences are manifested on the gravimetric map. The successful application of gravimetric methods depends on the following important factors: - Тhe difference in the volume mass (density) of the geological object being studied; - Тhe depth at which the studied object is located and the intensity of the maximum effect that can be caused under these conditions; - Тhe size of the surface on which the anomaly, caused by the investigated object, is 3 to 5 times the order of the accuracy of the measuring instrument; - Тhe sensitivity of the gravimeter used; - Тhe presence of all types of possible obstacles that may be present on the entire research area, including the impact of relief masses and deformations caused by anthropogenic action. [ABSTRACT FROM AUTHOR]