Vertical Displacement Velocity Research Articles

VALIDATION OF FULL-RESOLUTION DINSAR-DERIVED VERTICAL DISPLACEMENT IN CULTURAL HERITAGE MONITORING: INTEGRATION WITH GEODETIC LEVELLING MEASUREMENTS

Abstract. Towards revealing the potential of satellite Synthetic Aperture Radar (SAR) Interferometry (InSAR) for efficient detection and monitoring of Cultural Heritage (CH) encouraging resilient built CH, this study is devoted to the validation of InSAR-derived vertical displacements with a full-resolution perspective taking advantage of high-precision geodetic levelling measurements. Considering the Cathedral of Como, northern Italy, as the case study, two different Persistent Scatterer Interferometry (PSI) techniques have been applied to Cosmo-SkyMed high-resolution SAR images acquired in both ascending and descending orbit tacks within the time interval of 2010–2012. Besides using the simplified approach for obtaining the vertical displacement velocity from Line of Sight (LOS) velocity, a weighted, localized, multi-track Vertical Displacement Extraction (VDE) approach is proposed and evaluated, which uses the technical outcome of Differential InSAR (DInSAR) and spatial information. The results, using a proper PSI technique, showed that the accuracy level of extracted vertical displacement velocities in a full-resolution application is ca. 0.6 [mm/year] with a dense concentration of InSAR-Levelling absolute errors lower than 0.3 [mm/year] which are reliable and reasonable levels based on the employed validation framework in this study. Also, the weighted localized VDE can significantly decrease the InSAR-Levelling errors, adding to the reliability of the InSAR application for CH monitoring and condition assessment in practice.

Impact of Landscape Factors on Automobile Road Deformation Patterns—A Case Study of the Almaty Mountain Road

The geography of Kazakhstan is characterized by a diverse landscape and a small population. Therefore, certain automobile roads pass through unpopulated mountain regions, where physical road diagnostics are rare or almost absent, while landscape factors continue to affect the road. However, modern geo-information approaches and remote sensing could effectively provide the road diagnostics necessary to make timely control decisions regarding a road’s design, construction, and maintenance. To justify this assumption, we researched the deformation of a mountain road near Almaty city. Open access satellite images of and meteorological archival data for the region were processed. The resulting data were compared to validate the road’s deformation triggers. Extreme weather conditions’ impacts could be identified via road destruction (nearly 40 m longitudinal cracks, 15 m short transversal cracks, and two crack networks along a 50 m road section). The remotely sensed parameters (vertical displacement velocity, slope exposure, dissections, topographic wetness index, aspect, solar radiation, SAVI, and snow melting) show the complexity of triggers of extensive road deformations. The article focuses only on open access data from remote sensing images and meteorological archives. All the resulting data are available and open for all interested parties to use.

Quantifying Two-Dimensional Surface Displacements Using High-Resolution Cosmo-SkyMed, TerraSAR-X and Medium-Resolution Sentinel-1 SAR Interferometry: Case Study for the Tengiz Oilfield.

The present study was aimed at comparing vertical and horizontal surface displacements derived from the Cosmo-SkyMED, TerraSAR-X and Sentinel-1 satellite missions for the detection of oil extraction-induced subsidence in the Tengiz oilfield during 2018–2021. The vertical and horizontal surface displacements were derived using the 2D decomposition of line-of-sight measurements from three satellite missions. Since the TerraSAR-X mission was only available from an ascending track, it was successfully decomposed by combining it with the Cosmo-SkyMED descending track. Vertical displacement velocities derived from 2D Decomposition showed a good agreement in similar ground motion patterns and an average regression coefficient of 0.98. The maximum average vertical subsidence obtained from the three satellite missions was observed to be −57 mm/year. Higher variations and deviations were observed for horizontal displacement velocities in terms of similar ground motion patterns and an average regression coefficient of 0.80. Fifteen wells and three facilities were observed to be located within the subsidence range between −55.6 mm/year and −42 mm/year. The spatial analyses in the present studies allowed us to suspect that the subsidence processes occurring in the Tengiz oilfield are controlled not solely by oil production activities since it was clearly observed from the detected horizontal movements. The natural tectonic factors related to two seismic faults crossing the oilfield, and terrain characteristics forming water flow towards the detected subsidence hotspot, should also be considered as ground deformation accelerating factors. The novelty of the present research for Kazakhstan’s Tengiz oilfield is based on the cross-validation of vertical and horizontal surface displacement measurements derived from three radar satellite missions, 2D Decomposition of Cosmo-SkyMED descending and TerraSAR-X ascending line-of-sight measurements and spatial analysis of man-made and natural factors triggering subsidence processes.

Formation and termination of runaway beams during vertical displacement events in tokamak disruptions

A simple 0D model which mimics the plasma surrounded by the conducting structures (Kiramov and Breizman 2017 Phys. Plasmas 24 100702) and including self-consistently the vertical plasma motion and the generation of runaway electrons during the disruption is used for an assessment of the effect of vertical displacement events on the runaway current formation and termination. The total plasma current and runaway current at the time the plasma hits the wall is estimated and the effect of injecting impurities into the plasma is evaluated. In the case of ITER, with a highly conducting wall, although the total plasma current when the plasma touches the wall is the same for any number of injected impurities, however the fraction of the plasma current carried by runaway electrons can significantly decrease for large enough amounts of impurities. The plasma velocity is larger and the time when the plasma hits the wall shorter for lower runaway currents, which are obtained when larger amounts of impurities are injected. When the plasma reaches the wall, the scraping-off of the runaway beam occurs and the current is terminated. During this phase, the plasma vertical displacement velocity and electric field can substantially increase leading to the deposition of a noticeable amount of energy on the runaway electrons (∼hundreds of MJ). It is found that an early second impurity injection reduces somewhat the amount of energy deposited by the runaways. Also larger temperatures of the companion plasma during the scraping-off might be efficient in reducing the power fluxes due to the runaways onto the PFCs. The plasma reaches the q a = 2 limit before the runaway electron current is terminated and by that time the amount of energy deposited on the runaway electrons can be substantially lower than that expected until the beam is fully terminated. Negligible additional conversion of magnetic into runaway kinetic energy is predicted during the runaway deconfinement following the large magnetic fluctuations after q a = 2 is crossed for characteristic deconfinement times lower than 0.1 ms which is a characteristic timescale for ideal MHD instabilities to develop.

Multi-Temporal SAR Interferometry for Vertical Displacement Monitoring from Space of Tengiz Oil Reservoir Using SENTINEL-1 and COSMO-SKYMED Satellite Missions

This study focused on the quantitative assessment of the vertical displacement velocities retrieved using Sentinel-1 and Cosmo-SkyMed synthetic aperture radar images for the Tengiz oilfield. Tengiz oilfield was selected as a study area because of its historically reported continuous subsidence and limited up-to-date studies during recent years. The small baseline subset time-series technique was used for the interferometric processing of radar images acquired for the period of 2018–2020. The geospatial and statistical analyses allowed to determine the existing hotspots of the subsidence processes induced by oil extraction in the study area. Ground deformation measurements derived from the Sentinel-1 and COSMO-SkyMed satellite missions showed that the Tengiz oilfield continuously subsided during 2018–2020 with the maximum annual vertical displacement velocity around −77.4 mm/y and −71.5 mm/y, respectively. The vertical displacement velocities derived from the Sentinel-1 and the COSMO-SkyMed images showed a good statistical relationship with R2≥0.73 and RMSE ≤3.68 mm. The cumulative vertical displacement derived from both satellites for the most subsiding location also showed a good statistical relationship with R2 equal to 0.97 and RMSE = ± 4.69. The observed relative differences of measurements by both satellites were acceptable to determine the ongoing vertical surface displacement processes in the study area. These studies demonstrated a practical novelty for the petroleum industry in terms of the comparative assessment of surface displacement measurements using time-series of medium-resolution Sentinel-1 and high-resolution COSMO-SkyMed radar images.

Urban growth and land subsidence: Multi-decadal investigation using human settlement data and satellite InSAR in Morelia, Mexico

Limited attention is typically paid to the cause-effect relationship between land subsidence due to aquifers overexploitation in expanding metropolises and urban growth models and patterns. This paper implements an integrated urban and satellite Interferometric Synthetic Aperture Radar (InSAR) approach to investigate subsidence, multi-decadal urban growth and peopling trends in the Metropolitan Area of Morelia (ZMM) in the Mexican state of Michoacán. Stacking of JRC's Global Human Settlement Layer, DLR's World Settlement Footprint and INEGI's National Geostatistical Framework datasets reveals a predominant edge-expansion growth model, with urban densification in 1975–2020 and some sprawling in 1990–2000. Population of the ZMM doubled in the last 30 years, reaching over 1 million inhabitants. The ENVISAT and Sentinel-1 InSAR analysis confirms that subsidence is structurally-controlled by the main normal faults within the Cuitzeo half-graben. Differential sinking and ground discontinuities are aligned with buried tectonic faults and contrasting compressible sediment thickness. Non-linearly deforming subsidence bowls develop at extraction wells in both old and newly urbanized sectors of the ZMM. Maximum vertical displacement velocities increased from −2.5 cm/year in 2003−2010 to −9.0 cm/year in 2014–2021, with subsidence migrating towards recently urbanized zones. More than 250 new groundwater wells were added to the public registry since 2000, many of which within new urban sectors. Time-lapse InSAR reveals a 4 km2 rapidly subsiding bowl that formed at the largest social housing neighbourhood of Villas del Pedregal, as building lots were progressively completed and sold, and new wells registered. With angular distortions due to the differential subsidence reaching 0.12% in 2014–2021, new buildings and roads are exposed to fracturing and surface faulting risk of comparable level as the city historic building blocks located along the main faults. By providing useful insights into the relationship between urban growth and land subsidence in the ZMM, the approach proves valuable for application to other metropolises worldwide.

Dynamic deformation and fracture characteristics of a deep roadway surrounding rock based on the machine vision monitoring method

AbstractThe deformation and fracture of surrounding rock in deep underground engineering have the characteristics of time mutation and space continuity. In order to monitor and provide early warning of the dynamic deformation and fracture characteristics of deep surrounding rock, a real‐time digital displacement measuring instrument was developed in this paper. The proposed device represented a kind of surrounding rock deformation and fracture monitoring method, which had the continuous and real‐time advantages. Based upon the simulation experiments, the dynamic deformation and fracture of deep roadway surrounding rock were measured synchronously using the digital displacement measuring instrument testing system (DDMITS) and the V‐STARS measurement system. Comparative measurement results indicated that the DDMITS had a higher reliability. The deformation of roadway surrounding rock gradually increased with the increase of loading. The roof deformation and caving changing patterns in coal seam mining were studied using similar simulation experiments based on the DDMITS. The vertical displacement response of rock strata was more obvious than the horizontal displacement. There was a sharp increase in the vertical displacement during the collapse of the rock strata. Additionally, the vertical displacement velocity showed fluctuations. Meanwhile, the fluctuations in the vertical displacement acceleration increased significantly. The DDMITS could achieve full‐field measurement and the noncontact measurement of three‐dimensional deformation.

Surface deformation and earthquake potential in Surabaya from GPS campaigns data

Study by the National Centre for Earthquake Studies suggests the presence of two segments of Kendeng active fault, namely Surabaya fault and Waru fault in Surabaya. This study aims to investigate the surface deformation and earthquake potential in Surabaya that possibly related to the activities of those two faults. We use GPS campaigns data conducted in March 2017, September 2017, May 2018, and October 2018 and five GGPS CORS stations around Surabaya provided by the Indonesian Geospatial Information Agency. In total, 21 GPS stations data were processed to obtain horizontal and vertical displacement velocities in each station. The results showed almost all stations move toward southeast with the velocity rates range from 1.034 cm/yr to 5.674 cm/yr, except BM33 and SB07 that moves northeast with the velocity rates 4.065 cm/yr and 3.312 cm/yr respectively. For the vertical displacements, almost all stations subject to subsidence with the rates range from -0.190 cm/yr to -5.769 cm/yr. Only three stations subject to uplift namely BM23 with the rate of 0.234 cm/yr, BM24 with the rate of 2.844 cm/yr, and BM29 with the rate of 3.33 cm/yr. The strain analyses showed large shortenings in the area between two faults with the values up to 11.95 μstrain. From the results, we can conclude that the surrounding area of the two faults have different deformation patterns, and by confirming with geological data, we suggest that Surabaya has an earthquake potential due to the active faults.

Monitoring of an experimental motorway section

A portion of the lane reserved for slow vehicles on a motorway was totally rebuild of the A10 Motorway in the West of Paris. Four sections have been instrumented using classical strain gage sensors, placed at different depths within the pavement (subgrade, cement-treated subbase, and bituminous base) and temperature sensors. A fifth section is equipped with a more innovative instrumentation including geophones and temperature sensors, coupled with a remote data acquisition system. The purpose of this paper is to present the monitoring of these experimental sections since 2011. Strain gage measurements are used to develop a mechanical model of the pavement structure, to evaluate the modulus of the different pavement layers, as well as their evolution with time. The results confirm the good performance of the in-place recycled subbase. Geophones are very sensitive sensors measuring vertical displacement velocity. Different methods for the processing of these measurements are proposed in order to monitor pavement deflections and identify and classify truck silhouettes.

Use of agar/glycerol and agar/glycerol/water as a translucent brain simulant for ballistic testing

The suitability of agar/glycerol/water and agar/glycerol mixtures as brain simulants was investigated. Test specimens (n=15) (50x27×37mm) were fabricated for these different mixtures and conditioned to 12°C, 22°C, and 26°C prior to testing. For comparison, fresh deer brain specimens (n=20) were sourced and prepared to the same dimensions as the agar/glycerol(/water) mixtures and conditioned to 12°C and 37°C. High impact tests were carried out with a 0.22-caliber air rifle pellet and a high-speed camera was used to record the projectile as it passed through the specimens, allowing for energy loss and vertical displacement velocity calculation. Although the agar/glycerol/water mixture presented with similar vertical expansion and contraction of the specimens to the warm and cold deer brains, a two-fold decrease of the vertical expansion and contraction was noticed with the agar/glycerol specimens. Also considerably less extrusion of this mixture out of the exit and entry sides after specimen penetration was observed. Of the simulants tested, agar/glycerol/water was the most suitable brain simulant for ballistic testing and impact studies.

A role of the altitude gradient of the thermospheric wind velocity in ionospheric F-region dynamics

By processing the data of vertical ionospheric sounding in Almaty for 2000–2009, we obtained the distributions of the heights of the maximum (hmF) and bottom (hbotF) of the F2-layer, incremental changes in its semi-thickness (δh), the characteristic time of losses (τ), and the vertical displacement velocity of the node of the thermospheric wind (V) during the transitional time of the day during nighttime increases in the electron concentration at the layer maximum. The comparison of the measured V and modeled Vm velocities showed a certain discrepancy. The influence of the altitude gradient of the meridional thermospheric wind velocity on the behaviors of hmF, hbotF, δh, and τ during nighttime increases in the electron concentration is studied.

Low Order Modeling of a Metal Plate Under Vibrations

The Proper Orthogonal Decomposition (POD) method and the Galerkin projection are applied to study vibrations on an aluminum square plate. Data from the plate vibrations were obtained using a Laser Vibrometer and the Fringe Projection technique. The vibrations, within the range 100 to 5,000 Hz, on the metal plate were produced with an electrodynamical shaker. Due to the symmetrical nature of the plate, the vertical displacement velocity measurements were taken only on a rectangular grid of 7×8 points. The vertical displacement velocity measured at different locations and times, was synchronized with a full-field instantaneous image of the plate obtained from the Fringe Projection technique. The plate vibration measurements were used to calculate its eigenfunctions and the eigenvalues. It was found that a large fraction of the total energy of the vibration is contained within the first two POD modes. The essential features of the vibration are thus described by only the first two eigenfunctions. A reduced order model for the dynamical behavior is then constructed using the Galerkin projection of the equation of motion for the vertical displacement of a plate.

Avoidance behaviour in cod ( Gadus morhua) to a bottom-trawling vessel

The reaction of fish induced by a trawling vessel was measured using the Bergen Acoustic Buoy. It is a free-floating buoy with a split beam echo sounder system. Individual fish trajectories were obtained by target tracking methods, and average swimming velocities as a function of depth and time before and after passage of the vessel was calculated. A measure for the change in behaviour was applied, showing a significant response during and after propeller passage. The change in horizontal displacement speed is significant at all depths, while the change in vertical displacement velocity is significant at all but one layer of depth. The horizontal reaction seems to occur a bit later than the diving reaction. After the main response, a slightly higher mean horizontal displacement speed was observed for the deepest layers. This indicates a change in the fish state after being exposed to the vessel/gear.

What goes down must come up: symmetry in light-induced migration behaviour of Daphnia

During a short period of the year, Daphnia may perform a phenotypically induced diel vertical migration. For this to happen, light-induced swimming reactions must be enhanced both at dawn and at dusk. Enhanced swimming in response to light intensity increase can be elicited by fish-associated kairomone in the laboratory, if food is sufficiently available. However, during the light change at dusk the Daphnia are still in the hypolimnion, where no fish kairomone is present and both temperature and food availability is low. Still, what goes down must come up. This raises questions about how Daphnia tunes its light-induced swimming behaviour to prevailing conditions such that a normal diel vertical migration can be performed. We investigated the symmetry in behavioural mechanism underlying these diel vertical migrations in the hybrid Daphnia galeata × hyalina (Cladocera; Crustacea), with special interest for the environmental cues that are known to affect swimming in response to light increase. That is, we tested whether fish- associated kairomone, food availability, and temperature affected both swimming in response to light intensity increase and decrease similarly. We quantified swimming behaviour during a sequentially increased rate of light change. Vertical displacement velocity was measured and proved to be linearly related to the rate of the light change. The slope (PC) of the function depends on the value of the factors kairomone concentration, food availability, and temperature. The changes of the PC with kairomone concentration and with temperature were similar both at light intensity increases and decreases. The PC also increased with food concentration, although during light increases in a different way from during light intensity decreases. Low food availability inhibited swimming in response to light intensity increase, but enhanced swimming in response to light intensity decrease. Hence, ascent from the deep water layers with low food concentration at dusk is facilitated. These causal relations are part of a proximate decision-making mechanism which may help the individual Daphnia to tune migration to predation intensity and food availability [KEYWORDS: predation avoidance; diel vertical migration; behavioural mechanism; phototaxis; zooplankton]

Examination of the layer model of the frequency-domain interferometry theory applied in mesosphere–stratosphere–troposphere radars

The thickness and position of an atmospheric layer embedded in the radar volume can be resolved by using the frequency-domain interferometry (FDI) technique in accordance with an analytical expression, in which a single layer with Gaussian shape is assumed. However, the FDI experimental results obtained from the Chung-Li VHF radar show that the layer thickness is usually dependent on the layer position. In view of this, an attempt is made in this paper to interpret the observations. With the help of numerical simulation, we examine three FDI models: (1) a non-Gaussian layer, (2) single layer in company with background scatterers, and (3) multiple layers. The analytical FDI expression derived from the Gaussian-layer model is employed in the numerical study to calculate the layer position and layer thickness on the basis of the coherence and phase estimated from the examined layer model. It shows that the resultant thickness and position of the FDI layer are dependent on each other, which is in agreement with the observed thickness–position relations shown in this paper. Moreover, the numerical results can also provide a reasonable interpretation of the observations reported by earlier scientific workers, such as the discrepancy between the vertical displacement velocity of the layer and the vertical Doppler velocity, the difference in thickness between the FDI-derived layer and in situ observed temperature/humidity sheets, etc. We finally illustrate that the range weighting effect of the radar system plays a crucial role in the FDI-derived thickness–position relations.

Active faulting and earthquake hazard: The case study of the Chihshang Fault, Taiwan

The Longitudinal Valley Fault Zone of eastern Taiwan is the present-day plate boundary between the Philippine Sea Plate and the South China block of Eurasia. Repeated surveys of active deformation were carried out at five sites along its most active segment, the Chihshang Fault. Annual surveys during the period 1990–1997 reveal a rather constant slip velocity of 2.2 cm/yr in a N40°W direction, involving both a thrust component with horizontal shortening of nearly 1.7 cm/yr and a left-lateral component of nearly 1.4 cm/yr. The fault trends N18°E and dips 39–45° to the east. The vertical displacement velocity is about 1.3 cm/yr and the actual oblique offset of the fault increases at a rate of 2.6 cm/yr. Comparison with GPS data suggests that some additional deformation occurs on the edge of the Valley. Active faulting of the Chihshang Fault and of the entire Longitudinal Valley Fault Zone accounts for 24% and 37% (respectively) of the total shortening across the Taiwan collision in the N54°W direction of relative motion between the Philippine Sea Plate and the South China shelf. This distribution of relative displacements illustrates the major role played by this boundary, as a zone of mechanical weakness where tectonic partitioning occurs. Permanent surveying of the displacement on the Chihshang Fault has the potential to detect significant decrease in slip rates, and hence to predict forthcoming locking stages, which would increase earthquake hazard.

A theoretical comparison between apparent and real vertical ionization drift velocities in the equatorial F region

A theoretical analysis of the time dependent distribution of ionization in the low‐latitude ionosphere is performed by using a realistic dynamic computer model of the equatorial F region, with special interest in the vertical motions of the electron density profile at the magnetic equator. The time dependence of the F2 peak height, at the magnetic equator, is governed primarily by the electromagnetic plasma drift velocity. It is shown that, for special time periods during sunset and evening hours, when the height of the F layer is above a threshold of 300 km, the apparent vertical displacement velocity of the F layer, inferred from ionosonde measurements, is the same as the vertical plasma drift velocity, as determined from incoherent backscatter radar measurements in the F region.

Coupling of airborne sound into the earth: Frequency dependence

Simultaneous measurements have been made of sound pressure above the ground and seismic velocity below the ground surface resulting from a source suspended in the air a variable distance from the surface. The ratio of seismic velocity to acoustic sound pressure has been determined; there are peaks in the ratio in the vicinity of 45 and 90 Hz depending on the height of the speaker. The source–receiver distance was 10, 30, and 60 m; the source height was varied between 1 and 10 m. The frequency of maximum acoustic coupling was found to agree well with theory; the first and third shear modes appear to be excited. Results for vertical, horizontal, and radial motion indicate the coupled seismic signal is greatest for vertical, next greatest for radial, and least for transverse, though the difference between radial and vertical displacement velocities was not great and depended on the speaker altitude.