Anomalous Deformation Research Articles

Instrumental recording of slow deformation waves in the South Baikal geodynamic study site

Instrumental monitoring of rock deformation in the South Baikal geodynamic study site showed that they are realized in the form of long-term variations in different directions superimposed with short-time anomalous spikes. Analysis of the measured spatiotemporal monitoring series showed that anomalous deformations are caused by the propagation of deformation waves through the mountainous rocks. We estimated their lengths, periods, directions, and velocity of spatial migration. We found that propagation of deformation waves is accompanied by an increase in the temperature of rocks at each point of monitoring.

Nonstationary electrical activity in the tectonosphere-atmosphere interface retrieving by multielectrode sensors: case study of three major earthquakes in Central Italy with M>6

We present data analysis of multi-electrode measurements performed in the tectonosphere-atmosphere interface at Pizzoli and Chieti observatories located at distances 30–50 km and 90–110 km from earthquakes epicenters in Central Italy accordingly. Time intervals include 30 days of observations before earthquakes occurred on 24 August (M6.2), on 26 October (M6.1) and on 30 October, 2016 (M6.6). The recorded signals are two component time series with time step 1 s representing alternative and direct electromotive force components. Alternative electromotive force component in frequency band of 0.01 Hz to 4000 Hz is being recorded. Basic study has been carried out since 1989 at Kamchatka peninsula and since 2012 across Eurasia. The observation of nonstationary electric processes illustrates the nucleation of seismogenetic activity. We propose the hypothesis that nonstationary (sudden, abrupt in amplitude) electrical signals illustrate the proton permeability of rocks laying underneath the measuring sensor including a unique phenomenon of anomalous spontaneous deformation due to combination of proton environment and polymorphic transformation in condensed media. One of the interesting results is distinguishing the main zone of major earthquake nucleation which is corresponding as the earthquakes epicenters in Central Italy with M > 6. We suggest that by covering the northern, central and southern parts of Italy with a network of multi-electrode observatories near fault lines, towns and villages could pinpoint the possible coordinates of earthquake epicenter in a 30 day time window. The Chieti and Pizzoli observatories can form the basis of an extended network.

Complex Method of Detection Reliable Precursors of Stressed Rock Samples Failure

Studies of brittle rock samples failure were carried out in Laboratory of Geodynamics of Far-Eastern University, Vladivostok, Russia. It was assisted by servocontrol loading machine MTS-816, acoustic emission (AE) complex, and multi-channel complex. The regularities of formation and development of dissipative mesocracks structures in rock samples under uniaxial compression were determined as a result of complex deformation and acoustic experiments at final stage of loading. Anomalous deformations of high stressed rock samples were associated with acoustic characteristics. The system of reliable precursors of failure involving long-term and middle-term was established. This system of precursors reflects the stages of formation and development of dissipative mesodefects structures in high stressed rock samples.

Toroidal resonance: Relation to pygmy mode, vortical properties, and anomalous deformation splitting

We review a recent progress in investigation of the isoscalar toroidal dipole resonance (TDR). A possible relation of the TDR and low-energy dipole strength (also called a pygmy resonance) is analyzed. It is shown that the dipole strength in the pygmy region can by understood as a local manifestation of the collective vortical toroidal motion at the nuclear surface. Application of the TDR as a measure of the nuclear dipole vorticity is discussed. Finally, an anomalous splitting of the TDR in deformed nuclei is scrutinized.

Potential loess landslide deformation monitoring using L-band SAR interferometry

Multi-temporal InSAR technique can implement continuous earth surface deformation detection with long time scale and wide geographical coverage. In this paper, we first employ the Small Baseline Subset method to survey potential landslides in Guide County, Qinghai Province, which is identified as a loess landslide prone area for geological and climate conditions. Two anomalous deformation regions are detected by L-band Phased Array and L-band Synthetic Aperture Radar stacks. Then, qualitative and quantitative evaluations of the measuring points are given for understanding the distribution regularity of deformation. Finally, preliminary correlation between the time-series deformation and triggering factors is analyzed to explore the driving mechanism for landslide movement. The results demonstrate that L-band SAR has high potential in landslide monitoring applications and can be used as the basis for landslide recognizing, precursory information extracting, and early warning.

A statistical-based approach for determining the intensity of unrest phases at Stromboli volcano (Southern Italy) using one-step-ahead forecasts of displacement time series

The evaluation of the intensity of unrest phases at active volcanoes is a crucial topic in volcano hazard studies. This is particularly troublesome in the case of persistently active volcanoes like Stromboli (Southern Italy), where intense eruptive summit activity (overflows, strong spattering, powerful explosions) has in some cases anticipated a flank eruption. In this context, a new approach for the analysis of displacement data is introduced. Daily displacements of the Stromboli crater terrace measured between January 1, 2010, and August 7, 2014, by a ground-based interferometric synthetic aperture radar system were compared, in retrospect, to displacement predictions provided by an auto-regressive integrated moving average-based model. The methodology consisted in assessing when the actual displacements exceeded a fixed probability threshold for the forecasts (~95 %). Two sets of data were consequently produced: (1) series of residuals between actual displacements and model threshold (“anomalies”) and (2) series of normalized residuals between actual displacements and model threshold (“normalized anomalies”). This permitted to statistically identify and quantify the anomalous deformation at the crater terrace over the reference time interval of the analysis. Anomalies started to occur before each period of intense volcanic activity, highlighting the possibility to discern between background activity and unrest. Moreover, results indicated that the inflation of the crater terrace during the preparatory phase of the 2014 flank eruption was characterized by the greatest amount of anomalous deformation.

Coupled electrostatic and material surface stresses yield anomalous particle interactions and deformation

Like-charges repel, and opposite charges attract. This fundamental tenet is a result of Coulomb's law. However, the electrostatic interactions between dielectric particles remain topical due to observations of like-charged particle attraction and the self-assembly of colloidal systems. Here, we show, using both an approximate description and an exact solution of Maxwell's equations, that nonlinear charged particle forces result even for linear material systems and can be responsible for anomalous electrostatic interactions such as like-charged particle attraction and oppositely charged particle repulsion. Furthermore, these electrostatic interactions and the deformation of such particles have fundamental implications for our understanding of macroscopic electrodynamics.

On the ecological aspect of modern seismicity of the eastern Caucasus territory

The ecological problems that may occur in seismically active regions have not been paid enough attention until recently. The need to carry out forecasting geoecological research in the region is substantiated by the example of the eastern Caucasus territory. Methods of forecasting an imminent seismic event based on the analysis of a formed anomalous hydrogeodeformation field (HGD field) and deformation monitoring have been developed. It is recommended that works on seismic microzoning and the establishment of a network of seismometer stations proceed in the region.

Anomalous lattice deformation in GaN/SiC(0001) measured by high-speed in situ synchrotron X-ray diffraction

We report an anomalous lattice deformation of GaN layers grown on SiC(0001) by molecular beam epitaxy. The evolution of the lattice parameters during the growth of the GaN layers was measured by in situ synchrotron X-ray diffraction. The lattice parameters in the directions parallel and normal to the surface showed significant deviation from the elastic strains expected for lattice-mismatched films on substrates up to a thickness of 10 nm. The observed lattice deformation was well explained by the incorporation of hydrostatic strains due to point defects. The results indicate that the control of point defects in the initial stage of growth is important for fabricating GaN-based optoelectronic devices.

Anomalous mechanical strengths and shear deformation paths of Al2O3polymorphs with high ionicity

Alumina (Al2O3) formed by selective oxidization provides an effective way to protect aluminide alloys against corrosion for sustainable applications.

On a method for reducing interpretation uncertainty of poorly imaged seismic horizons and faults using geomechanically based restoration technique

To reduce exploration risk and optimize production in structurally complex areas, the geologic interpretation must be based on sound geomechanical principles. Despite advances in 3D seismic acquisition and processing techniques as well as in the availability of computationally robust interpretation software, the challenge associated with interpreting complex structures from seismic reflection data is that highly deformed areas surrounding faults, folds, and salt surfaces are often poorly imaged and therefore their interpretation is highly uncertain. We have developed a methodology that should help geophysicists quickly check the strengths and weaknesses of their interpretation and to automatically reduce the uncertainty in a faulted horizon geometry. Our workflow consisted of restoring interpreted seismic horizons and relating the concentrations of computed deformation attributes to areas of interpretation uncertainty. We used the technique based on an iterative finite-element formulation that allowed unfolding and unfaulting of 3D horizons using physical elastic behavior. A fast algorithm has been developed to automatically correct the interpreted structures in zones that exhibited anomalous deformation concentrations after restoration. This approach is able to mechanically check and reduce uncertainty in a faulted seismic horizon interpretation. Its application to synthetic and reservoir data has a high degree of reliability in the characterization of structurally complex reservoirs. This technique is also applicable to 2D models (geologic cross sections) and 3D models (volume).

Mitigation of atmospheric phase delays in InSAR data, with application to the eastern California shear zone

AbstractWe present a method for estimating radar phase delays due to propagation through the troposphere and the ionosphere based on the averaging of redundant interferograms that share a common scene. Estimated atmospheric contributions can then be subtracted from the radar interferograms to improve measurements of surface deformation. Inversions using synthetic data demonstrate that this procedure can considerably reduce scatter in the time series of the line‐of‐sight displacements. We demonstrate the feasibility of this method by comparing the interferometric synthetic aperture radar (InSAR) time series derived from ERS‐1/2 and Envisat data to continuous Global Positioning System data from eastern California. We also present results from several sites in the eastern California shear zone where anomalous deformation has been reported by previous studies, including the Blackwater fault, the Hunter Mountain fault, and the Coso geothermal plant.

Abrupt magma chamber contraction and microseismicity at Campi Flegrei, Italy: Cause and effect determined from strainmeters and tiltmeters

AbstractIn March 2010 two borehole strainmeters and three Michelson tiltmeters within the Campi Flegrei volcanic system, Italy, registered an abrupt deformation signal that was followed 20 min later by seismic slip on a pair of onshore normal faults. We demonstrate that the observed strain changes were caused by a small but rapid volume decrease in a previously identified offshore ellipsoidal magma source or part of it. Although the total deflation was below the detectability of interferometric synthetic aperture radar and GPS, deflation observed rates were briefly 2 orders of magnitude more rapid than decadal inflation rates. We conclude that this high dilatational contraction rate was responsible for triggering seismicity and that this process may be responsible for the normal faulting often observed in the Campi Flegrei region. Our study quantifies the crucial role played by a transient, minor reduction in dilatational stress, in triggering slip on a fault near critical failure. Our subsurface measurements of strain and tilt registered anomalous deformation three sigma above background noise levels 17 min before the onset of microseismicity suggesting strain measurements have potential utility as an early warning system for the city of Naples.

Statistical shape model reconstruction with sparse anomalous deformations: Application to intervertebral disc herniation

Many medical image processing techniques rely on accurate shape modeling of anatomical features. The presence of shape abnormalities challenges traditional processing algorithms based on strong morphological priors. In this work, a sparse shape reconstruction from a statistical shape model is presented. It combines the advantages of traditional statistical shape models (defining a ‘normal’ shape space) and previously presented sparse shape composition (providing localized descriptors of anomalies). The algorithm was incorporated into our image segmentation and classification software. Evaluation was performed on simulated and clinical MRI data from 22 sciatica patients with intervertebral disc herniation, containing 35 herniated and 97 normal discs. Moderate to high correlation (R=0.73) was achieved between simulated and detected herniations. The sparse reconstruction provided novel quantitative features describing the herniation morphology and MRI signal appearance in three dimensions (3D). The proposed descriptors of local disc morphology resulted to the 3D segmentation accuracy of 1.07±1.00mm (mean absolute vertex-to-vertex mesh distance over the posterior disc region), and improved the intervertebral disc classification from 0.888 to 0.931 (area under receiver operating curve). The results show that the sparse shape reconstruction may improve computer-aided diagnosis of pathological conditions presenting local morphological alterations, as seen in intervertebral disc herniation.

Anomalous Plastic Deformation and Sputtering of Ion Irradiated Silicon Nanowires.

Silicon nanowires of various diameters were irradiated with 100 keV and 300 keV Ar+ ions on a rotatable and heatable stage. Irradiation at elevated temperatures above 300 °C retains the geometry of the nanostructure and sputtering can be gauged accurately. The diameter dependence of the sputtering shows a maximum if the ion range matches the nanowire diameter, which is in good agreement with Monte Carlo simulations based on binary collisions. Nanowires irradiated at room temperature, however, amorphize and deform plastically. So far, plastic deformation has not been observed in bulk silicon at such low ion energies. The magnitude and direction of the deformation is independent of the ion-beam direction and cannot be explained with mass-transport in a binary collision cascade but only by collective movement of atoms in the collision cascade with the given boundary conditions of a high surface to volume ratio.

ICONE23-1582 Atomistic simulation of yield and plastic deformation in bulk nanostructured metals

The influence of dislocation density on yield strength, which is a key factor in the anomalous deformation behavior in UFG metals, was investigated by huge scale atomistic simulations. Polycrystalline models with intragulanular Frank-Read sources were constructed to elucidate the relationship between the inter- and intra-granular plastic deformation processes and the mechanical properties. Then the uniaxial tension and compression were applied to the polycrystalline copper. Consequently it was found that Frank-Read sources were activated prior to intergranular dislocation emission, and the yield event of the whole system seems to occur when some dislocation sources activated. The yield stress is strongly influenced by the number of intragranular dislocation sources, i.e., dislocation density. Additionally, the Bauschinger effect of UFG metals is caused by the change in dislocation density in the process of forward and backward deformation.

Identifying hazards associated with lava deltas

Lava deltas, formed where lava enters the ocean and builds a shelf of new land extending from the coastline, represent a significant local hazard, especially on populated ocean island volcanoes. Such structures are unstable and prone to collapse—events that are often accompanied by small explosions that can deposit boulders and cobbles hundreds of meters inland. Explosions that coincide with collapses of the East Lae ‘Apuki lava delta at Kīlauea Volcano, Hawai‘i, during 2005–2007 followed an evolutionary progression mirroring that of the delta itself. A collapse that occurred when the lava–ocean entry was active was associated with a blast of lithic blocks and dispersal of spatter and fine, glassy tephra. Shortly after delta growth ceased, a collapse exposed hot rock to cold ocean water, resulting in an explosion composed entirely of lithic blocks and lapilli. Further collapse of the delta after several months of inactivity, by which time it had cooled significantly, resulted in no recognizable explosion deposit. Seaward displacement and subsidence of the coastline immediately inland of the delta was measured by both satellite and ground-based sensors and occurred at rates of several centimeters per month even after the lava–ocean entry had ceased. The anomalous deformation ended only after complete collapse of the delta. Monitoring of ground deformation may therefore provide an indication of the potential for delta collapse, while the hazard associated with collapse can be inferred from the level of activity, or the time since the last activity, on the delta.

A Raman-spectroscopic study of indentation-induced structural changes in technical alkali-borosilicate glasses with varying silicate network connectivity

We report on the deformation behavior of a series of glasses in the ternary alkali-borosilicate system. Vickers indentation was applied to different samples and structural changes were studied by micro-Raman spectroscopy. Selected sodium- and potassium-borosilicate glasses, a soda-lime silicate glass and pure vitreous SiO2 were chosen as models for technical glasses, as their varying content of non-bridging oxygen atoms affects the connectivity of the silicate and borate sub-networks. Indentation experiments were performed with different loads and two different load times in order to analyze the response of the two sub-networks in the studied glasses.The measured Raman spectra show distinct indentation-induced changes in the glass structure. These changes depend not only on the borate concentration, but also on the silicate sub-network's connectivity and reflect anomalous (densification-driven) and normal (shear-driven) deformation mechanisms. Using vitreous SiO2 as reference material, indentation-induced structural changes were also correlated to hydrostatic compression experiments from the literature in order to develop a more detailed picture of the apparent evolution of the local compaction in and around the indent.

Photo-Induced Anomalous Deformation of Poly(N-Isopropylacrylamide) Gel Hybridized with an Inorganic Nanosheet Liquid Crystal Aligned by Electric Field.

Poly-(N-isopropylacrylamide) (PNIPA) hydrogel films doped with uniaxially aligned liquid crystalline (LC) nanosheets adsorbed with a dye are synthesized and its anomalous photothermal deformation is demonstrated. The alignment of the nanosheet LC at the cm-scale is easily achieved by the application of an in-plane or out-of-plane AC electric field during photo-polymerization. A photoresponsive pattern is printable onto the gel with μm-scale resolution by adsorption of the dye through a pattern-holed silicone rubber. When the gel is irradiated with light, only the colored part is photothermally deformed. Interestingly, the photo-irradiated gel shows temporal expansion along one direction followed by anisotropic shrinkage, which is an anomalous behavior for a conventional PNIPA gel.

Anomalous deformation twinning in coarse-grained Cu in Ag60Cu40 composites under high strain-rate compressive loading

Abstract The deformation response of a directionally solidified Ag60Cu40 eutectic alloy with a cube-on-cube orientation relationship between Ag and Cu subjected to high strain-rate 103 s−1 compressive loading was examined. Loading at 45° and 90° to the growth axis, near [ 001 ] and [ 11 1 ¯ ] local crystal orientations, respectively, resulted in deformation twinning and dislocation slip in both Ag and Cu under conditions where deformation twinning would not normally be expected in Cu. In contrast, loading at 0° and 90° to the growth axis, near 〈 101 〉 local crystal orientations, resulted in the primary deformation mode being dislocation slip. These results are interpreted in terms of the influence of loading axis with respect to the local crystal orientation in the directionally solidified alloy and on slip transmission from Ag into Cu.