Correction: Dammann et al. Ground-Based Radar Interferometry of Sea Ice. Remote Sens. 2021, 13, 43

In the original article [...]

GEODYNAMICS

The most dangerous exogenous geological processes (EGP) in terms of the amount of damage caused to economic objects include: landslides, karst, flooding, abrasion, mudslides, etc. The distribution and intensity of EGP are determined by the peculiarities of geological and geomorphological structure of the territory, its tectonic, neotectonic and seismic regime, as well as hydrological, climatic, hydrogeological paleo- and modern conditions. Solotvynsky salt mine is one of the oldest enterprises in Transcarpathia. The field has been exploited since the Roman Empire. In 1360, a settlement of salt miners, Solotvyno, was founded on the site of the mine, which later became a center of salt production and a royal monopoly. There are a total of nine mines in the field. In 1995-1996 and 2001, floods began flooding mines. In 2005, landslides and karst abysses intensified in Solotvyno, leading to damage to residential buildings, roads and infrastructure. There was a complete flooding of the mines of two mines. Currently, dangerous natural and man-made processes are observed on the territory of the salt mine and adjacent territories. This is mainly salt karst, both underground and surface, the collapse of areas in the location of mines, as well as landslides. Therefore, the purpose of the research is to conduct a geodynamic audit of SOLOTVYNSKY SALT MINE SE and the surrounding area with the possibility of identifying areas with subsidence or rise of the earth's surface, which are gradually slowing down, accelerating or developing at a constant rate. Output data. Radar interferometry data in the period from April 30, 2016 to June 25, 2018 were used for research and performance of geodynamic audit of SOLOTVYNSKY SALT MINE SE and the adjacent territory. Modern methods of interferometric processing of satellite radar data are used in the work: the method of "PS" – the method of constant scatterers, and the method SBAS – the method of small baselines. The method of geometric leveling was used to measure vertical displacements in some places on the earth's surface in order to verify interferometric data. Monitoring of the area of interest was carried out using modern technologies of satellite radar interferometry. According to the results of observations of landslides and individual objects by space (radar interferometry) and ground (geometric leveling) methods, a high correlation of data was recorded and the presence of zones of active subsidence in the mining area was confirmed.

Experimental dynamic analysis of the arch road bridge

The paper presents an experimental dynamic analysis of the existing road bridge across the Labe river at Valy village in the Czech Republic. The observed structure is a bridge with 6 spans 23.1 m, 31.5 m, 84.0 m, 31.5 m and 23.1 m long. The horizontal load-bearing structure is a composite structure with two main steel girders and a lower reinforced concrete deck. The load-bearing structure is reinforced in the main span by the arch, this structural system is also called the Langer beam. The experiment was realized in three stages. The first one was performed in May 2020 before its opening, the second stage of the described experiment was realized in August 2020 and the third one was carried out in April 2021. The main purpose of the first stage was to determine in detail the natural frequencies and mode shapes of the whole bridge horizontal load-bearing structure also including the arch. The electrodynamic shaker, that was located on the bridge deck in the quarter of the main bridge span, was used for excitation of the bridge vibration. The measured characteristics of the natural vibration were compared with the calculated ones. Based on this comparison, the theoretical bridge model was verified. Basic objective of the second experiment stage was to verify new approach to dynamic response measurement – radar interferometry realized by two synchronized radars. The vibrations of the bridge caused by the standard road traffic and also by pedestrians were observed concurrently by both radar interferometry and classical approach realized by high sensitive piezoelectric accelerometers. The experiment was focused on the main span of the bridge only and the levels of forced vibration were observed primarily. However, the fundamental natural frequencies were also evaluated. The third stage was carried out by classical approach only. Again, the bridge vibration caused by the usual road traffic and pedestrians were measured in the main bridge span only because this section of the bridge was the most dynamically sensitive. Again, the levels of forced vibration were observed and the fundamental natural frequencies were determined. The evaluated natural frequencies from all three experiment stages were consequently compared.

On the Connection between the 2008–2009 Activation of the Koryakskii Volcano and Deep Magmatic Processes

Abstract—The last activation of the Koryakskii volcano in 2008–2009 was accompanied by intense fumarolic and seismic activity. Volcanic activity peaked in March–April 2009 when ash plume rose to a height of 5.5 km and extended laterally over more than 600 km. To understand the dynamics of the volcanic processes and to forecast the further course of the events, it is relevant to establish whether the eruption was associated with a rise of magma to beneath the volcanic edifice or caused by fracturing of the volcano’s basement and penetration of groundwater into a high temperature zone. Based on the analysis of the images from the Japanese satellite ALOS-1 using satellite radar interferometry methods, the slope displacements of the Koryakskii volcano during its last activation have been estimated for the first time. The displacements reach 25 cm and cannot be explained by the formation of a layer of volcanic ash deposits or by the slope processes. The most likely cause of the displacements should be recognized to be the intrusion of magmatic material into the volcano edifice with the formation of a fracture with its lower edge at a depth of 0.5 km above sea level, with a size of 1.0 and 2.4 km along the strike and dip, respectively, and with a dip angle from 45° to 60°. Therefore, the processes taking place beneath the volcano can be threatening to the nearby localities and infrastructure and require continuous monitoring.

Analysis and correction of meteorological disturbance observed by ground radars in complex environment

Ground radar interferometry technology, as a new tool for active remote sensing, has been widely used in the detection of a variety of targets, including landslides, bridges, mines, and dams. This technique usually employs a continuous observation mode with no space baseline. The detection accuracy is mainly affected by meteorological disturbances and noise in the observation environment. In a complex observation environment, meteorological disturbances can lead to phase errors of 10 mm or more, and the effects are different in the range and azimuth directions; this can seriously affect the accuracy of the measurement. In this paper, we analyze the spatial distribution of the phase of meteorological disturbances based on radar monitoring experiments in a complex environment, and propose a correction method that reduces the atmospheric disturbance phase to less than 0.6 mm and effectively improves radar observation accuracy.

On the integration of multi-temporal synthetic aperture radar interferometry products and historical surveys data for buildings structural monitoring

The management and the safeguard of existing buildings and infrastructures are actual tasks for structural engineering. Non-invasive structural monitoring techniques can provide useful information for supporting the management process and the safety evaluation, reducing at once the impact of disturbances on the structure’s functionality. This paper focuses on the exploitation of advanced multi-temporal differential synthetic aperture radar interferometry (DInSAR) products for the structural monitoring of buildings and infrastructures, subjected to different external actions. In this framework, a methodological approach is proposed, based on the integration of DInSAR measurements with historical sources, accurate 3D modelling and consistent positioning of the reflecting targets in the GIS environment. Documentary sources can prove particularly helpful in collecting technical information, to reconstruct an accurate 3D geometry of the building under monitoring, limiting in-situ surveys. The analysis of DInSAR-based displacements time series and mean deformation velocity values allows the identification of possible critical situations for buildings to be monitored. The paper presents different approaches, with increasing accuracy levels, to study the active deformative processes of the examined buildings and the related damage assessment. An insight into these interpretative approaches is given through the application of the proposed procedure to two case studies in the city of Rome (Italy), the residential building named Torri Stellari in Valco San Paolo (1951–1953) and the housing complex referred to as Corviale (1967–1983), by exploiting the whole COSMO-SkyMed data archive (both ascending and descending acquisitions), collected during the 2011–2019 time interval. Pros and cons of the various approaches are deeply discussed, together with an estimation of the required computational effort.