Pseudo 3D UMASW For Offshore Windfarm Development

Navigation in offshore wind farm (OWF) areas is essential for construction, maintenance, safety, and traditional activities like fishing. However, the presence of OWFs extends to sea routes, negatively impacting maritime transport economics. This paper examines navigational risk indicators in the vertical and horizontal planes of the ship domain for three representative vessels navigating under different hydrometeorological conditions within the location of a proposed offshore wind farm in the Polish sector of the Baltic Sea. The study compares three types of domain parameters defined by the PIANC guidelines, Coldwell’s two-dimensional model, and Rutkowski’s three-dimensional model. The analysis includes navigational hazards located ahead of the ship’s bow and astern from the aft, as well as keeping under-keel and over-head clearance. Besides the main numerical indicators of navigational risk estimated for obstacles on the port and starboard sides, the study emphasizes the importance of such additional factors. The primary objective of this paper is to identify the ship types that can navigate and fish safely in proximity to and within the OWF area. The analysis employs hydrometeorological data, mathematical models, and operational data derived from maritime navigation and maneuvering simulators. This comprehensive approach aims to enhance maritime safety in OWF areas.

Newly built offshore wind farms (OWFs) create a collision risk between ships and installations. The paper proposes a real-time traffic monitoring method based on machine vision and deep learning technology to improve the efficiency and accuracy of the traffic monitoring system in the vicinity of offshore wind farms. Specifically, the method employs real automatic identification system (AIS) data to train a machine vision model, which is then used to identify passing ships in OWF waters. Furthermore, the system utilizes stereo vision techniques to track and locate the positions of passing ships. The method was tested in offshore waters in China to validate its reliability. The results prove that the system sensitively detects the dynamic information of the passing ships, such as the distance between ships and OWFs, and ship speed and course. Overall, this study provides a novel approach to enhancing the safety of OWFs, which is increasingly important as the number of such installations continues to grow. By employing advanced machine vision and deep learning techniques, the proposed monitoring system offers an effective means of improving the accuracy and efficiency of ship monitoring in challenging offshore environments.

Seismic shear wave velocity profiles were acquired from 10 boreholes in central Illinois and compared to shear wave velocity profiles generated from the multichannel analysis of surface wave (MASW) data acquired at the borehole locations. The main objective was to determine if the shear wave velocity measurements from the MASW are reliable and can be used to characterize the glacial geology in central Illinois. The boreholes penetrated through glacial sediment consisting of multiple units of till, sandy silt, sand and gravel, and silty clay. The downhole data were acquired in PVC-cased holes drilled to depths ranging from 30 to 60 m using a three-component downhole geophone and a surface source. Travel times of the first-arrival seismic waves were analyzed using the direct and interval methods to generate 1-D seismic velocity profiles. The MASW profiles were acquired using 24-channel engineering seismograph with 1.5 m geophone spacing. The data were analyzed to generate 1-D velocity profile at each borehole location. Correlating the velocity profiles from both methods shows that the velocity values compare fairly well and demonstrate that the MASW is a reliable method to measure shear wave velocity of the subsurface materials.

The installation of offshore wind farms (OWFs) adds artificial hard substrates into naturally soft-bottom areas, changing the local biodiversity. The turbine foundations are rapidly colonized by colonizing organisms, mainly consisting of suspension feeders that can potentially reduce the local primary producer standing stock. In this study, we estimated the amount of organic matter processed by colonizing assemblages of OWFs. We conducted a laboratory pulse-chase experiment, by offering 13C-labelled fragmented microalgae to PVC panels colonized by OWF colonizing fauna. The blue mussel Mytilus edulis showed the highest biomass-specific carbon assimilation, while the high densities of the amphipod Jassa herdmani resulted in the highest total carbon assimilation. By upscaling our results to the total number of the installed offshore wind turbines in the Belgian part of the North Sea, we estimate that these species can reduce the local primary producer standing stock in the area by ca. 1.3%. Mytilus edulis and J. herdmani communities colonizing offshore wind turbine foundations significantly increase carbon assimilation compared to natural soft sediment macrofauna inhabiting the same surface area (i.e. footprint of the turbines).

In this study, two different historical structures built in Trabzon have been processed by ambient vibrations and seismic refraction measurements. One of the investigated historical structures is the Ataturk Pavilion built in the nineteenth century, and the other one is Hagia Sophia which was built in the thirteenth century. These two buildings are among the most important historical buildings in Trabzon and are very important for the tourism of the city. In order to determine peak/s frequency and amplitude from the horizontal-to-vertical spectral ratios (HVSRs), we have performed several measurements of ambient vibrations both inside (at different floors) and outside (on the ground) of structures. We have also conducted seismic prospecting to evaluate the vertical 1D and 2D profile of longitudinal and shear seismic waves, Vp and Vs, respectively. To this purpose, we have performed seismic refraction tomography and MASW. Ambient vibrations and seismic measurements were compared with each other. The results show that average predominant frequencies and HVSR amplitudes of inside and outside of Ataturk Pavilion are 4.0 Hz, 7.8 Hz and 2.6, 2.3, respectively. The Vp values vary from 300 to 2070 m/s, and the Vs for maximum effective depth is up to 790 m/s in Ataturk Pavilion. On the other hand, average predominant frequencies and HVSR amplitudes of inside and outside of Hagia Sophia and its tower are 4.7, 4.4 and 2.4 Hz and 1.6, 1.8 and 6.9, respectively. Vp values range from 450 to 2200 m/s, and Vs for maximum effective depth is also up to 1000 m/s in Hagia Sophia. The frequency values (F0 = Vs/4 h) calculated from the velocities up to the maximum effective depth for Ataturk Pavilion are in good agreement with the predominant frequency values determined from ambient vibrations. Ataturk Pavilion and Hagia Sophia soils have been classed according to Eurocode 8 by using VS30 values. The class was defined as “B.” Moreover, the bedrock in studied area is basalt. The high Vp and Vs values are also compatible with the lithology. The HVSR curves measured at the Hagia Sophia show the presence of clear peaks when compared to the Ataturk Pavilion. At the same time, there are marked velocity changes in the Vs sections calculated in both areas. As a result, in both areas there are significant impedance contrasts in the subsoil. However, this impedance contrast is more evident in Hagia Sophia. This could be also compatible with a lithological transition. The possible soil–structure interaction was investigated by using all the results and evaluated in terms of resonance risk. It is thought that the probability of resonance risk at Ataturk Pavilion is low according to the ambient vibrations measurements. However, resonance risk should be taken into consideration at Hagia Sophia site since the predominant frequency values are very close to each other. Finally, this site should be investigated in detail and necessary precautions should be taken against the risk of resonance.

Environmental vibrations induced by human activities such as traffic, construction or industrial manufacturing can cause disturbance among residents or to vibration sensitive equipment in buildings. In Sweden, geological formations of soft clay overlying a stiff bedrock are soil conditions prone to ground vibrations that are encountered both in urban areas and along parts of the national railway network. This paper presents an extensive investigation of the small-strain soil properties for the prediction of environmental ground vibrations in a shallow clay where the bedrock is situated at 7.5 m depth. The small-strain properties are estimated using available empirical correlations, bender elements, seismic cone penetration tests, seismic refraction and inversion of surface wave dispersion and attenuation curves. The results are synthesised into a dynamic layered soil model which is validated by measurements at the soil's surface at source-receiver distances up to 90 m in the frequency range 1–80 Hz. Analyses of uncertainties in the estimated values of wave speeds and material damping are performed by model investigations, indicating that surface wave tests overestimate the damping compared to bender element tests. The properties of the topmost unsaturated part of the soil is found to have a significant influence on the response at large distances, caused by critically refracted P-waves resonating in the top layer.

The recent, rapid growth of offshore wind energy has highlighted significant gaps in our ability to properly assess impacts on wildlife species and habitats. Despite the reported and conceived small and local impacts at small and medium-sized offshore wind farms, the experience with future large-scale wind farms may show otherwise. At the same time the industry now faces daunting logistic and scientific challenges as the construction sites move offshore both in relation to the assessment of the status of habitats and species, and in relation to the estimation of environmental effects. The key problems are lack of reliable models both of the distributional dynamics and of the habitat displacement and related impacts on populations of the species in question. This situation has hampered decision-making in relation to the management of the offshore wind energy sector by introducing unnecessary conflicts with conservation interests. As shown in this paper habitat models may offer solutions to many environmental barriers by providing data in high spatio-temporal resolution about the distribution of sensitive species. Detailed data about the distribution of sensitive species is required in order to:  Predict likely changes in distribution arising from natural dynamic change in the marine environment;  Evaluate more accurately the potential loss of habitat arising from exclusion (displacement) of priority and sensitive fauna from offshore wind farm areas as induced by disturbance and underwater noise emissions;  Assess the impact of cumulative habitat loss on priority and sensitive species arising from wind farm construction;  Avoid conflicts in future offshore wind energy schemes associated with environmentally sensitive areas. The programmes of biological sampling that are typically carried out for the offshore industry have documented problems associated with biological sampling in a dynamic environment. Even benthic habitats are not stable, and as the weather windows during which sampling of species and habitats is typically undertaken are relatively small interpretation and generalisation of results from baseline surveys is often constrained. Examples of such constraints are the lack of information on the distribution of food supply to higher trophic levels like birds, and the lack of information on the variation of habitats at

Multi-component high resolution seismic reflection data were acquired at the Uppsala University field test site in Marsta, Sweden, in March 2019 with the aim of obtaining an improved understanding of the subsurface structure in the area. An advantage of the site is that a number of boreholes have been drilled there for both hydrogeological and geophysical purposes, allowing surface geophysics to be compared with downhole information. The presence of a low velocity layer above the water table generates significant processing challenges due to trapped waves. A further complication with the data is that the upper part of this layer was frozen at the time of the survey, resulting in the sediments just below the surface having a significantly higher velocity than those below. By analyzing and processing both the vertical and radial component data it was possible to build a velocity model that is consistent with the observed data. A strong PS converted reflection allows the bedrock to be imaged on the radial component stacks to much higher resolution than on the vertical component stacks. Both common conversion point binning and pre-stack depth migration were used to process the radial component data. We confirmed that our processing strategy was effective by generating synthetic data that were processed in a similar manner as the real data. The PS images indicate a step in the bedrock of about 2 m, with depth to it increasing from about 15 m to 17 m close to one of the boreholes. This step is not observed on the PP stacks, due to their lower resolution.

High-resolution seismic reflection profiles and well data from the western Snake River plain basin are used to identify a buried lacustrine delta system within Neogene Idaho Group sediments near Caldwell, The delta system is detected, 305 m (1000 ft) deep, near the center of the basin by progradational clinoform reflections having dips of 2-5°, a slope typical of prodelta surfaces of modern lacustrine delta systems. The prodelta slope relief, corrected for compaction, indicates the delta system prograded northwestward into a lake basin 255 m (837 ft) deep. Resistivity logs in the prodelta mud and clay facies are characterized by gradual upward increase in resistivity and grain size over a thickness of about 100 m (300 ft). Lithology of the prodelta is mostly c lcareous claystone, with several layers of fine sand, some of which fine upward, indicating a density-flow mechanism of transport and deposition. Delta-plain and front sediments are mostly very fine-grained, well-sorted sand separated by thin mud layers. These sediments produce several to five cycles of horizontal, high-amplitude reflections with a toplap relationship to prodelta clinoforms. The sands have an abrupt lower contact with prodelta muds and have high resistivity on logs. In this study, permeable lacustrine sands within a predominantly mud and clay section are located by using high-resolution seismic reflection data. Identification of a delta system in the Idaho Group provides insight into the history of Pliocene Lake Idaho. The present depth of the delta/prodelta facies contact of 305 m (1000 ft) is 445 to 575 m (1460-1900 ft) below the lake deposits on the margins. Estimated subsidence from compaction is 220 m (656 ft), and the remaining 225 to 325 m (740-1066 ft) is attributed to tectonic downwarping and faulting. The original lake area had been reduced to one third of the original 13,000 km2 (5000 mi2) by the time the delta front prograded to the Caldwell area. The original lake area may have been sufficient to evaporate most of the inflow, and the lake may have only occasionally spilled into other basins. Diminished area for evaporation later in the history of the lake, combined with reduced evaporation accompanying onset of the ice ages, may have caused the lake to rise and overtop a basin sill about 2 Ma, and subsequently deepen Hells Canyon.

The Oligocene-Miocene Molasse basin along the northern rim of the Swiss Alps is affected by a major fault zone that separates Plateau Molasse to the north from Subalpine Molasse to the south. As a result of alpine compression, thrusts along this zone brought up Subalpine Molasse rocks by an amount of up to 1000 m. On the northern shore of Lake Geneva, near the City of Lausanne, the fault zone is well defined (Fig. 1). However, its extension in the lake and on its southern shore is not well known. Geology on both sides of the lake, however, indicates that major changes in the distribution of Molasse units occur in this region. Locating the Molasse fault zone across Lake Geneva would help to better understand geology and would provide important constraints on tectonic models of the Alps. In order to study the extension of the Molasse fault zone across Lake Geneva, we conducted a 2-D high-resolution multi-channel seismic reflection survey. Molasse units in the lake are overlain by Quaternary sediments up to 300-400 m thick (Vernet et al. 1974). Our data imaged these sediments and detected several faults in the Molasse units.

During the last decades we have assisted at a considerable shift from laboratory testing to in situ testing to the point that, today, in situ testing often represent the major part of a geotechnical investigation. Recommendations given in the State of the Art at the last Geotechnical World Conference in 2009 and in the Mitchell Lecture at the last International Conference on Geotechnical and Geophysical Site Characterization in 2012 indicate that direct-push in situ tests, such as the Seismic Cone Penetration Test (SCPT) and the Seismic Dilatometer Test (SDMT), are fast and very convenient tests for routine site investigations. The aim of this paper is to describe the SDMT, the obtained information and some engineering applications for design infrastructures: settlements for bridges, subgrade compaction control for roads and liquefaction for harbors.

On the relationship between structure, morphology and large coseismic slip: A case study of the Mw 8.8 Maule, Chile 2010 earthquake

In this study, we compared a model of bedrock depth derived from a high resolution seismic dataset to a very extensive set of geotechnical bedrock depth estimations. The results of both methods are in very good agreement on the larger scale, but also show considerable differences in some locations. These differences are usually attributed to errors in the refraction model since it has generally a lower accuracy and is affected by unresolved near-surface velocity variations. However, we found several locations where the data consistently indicate that the geotechnical sounding yielded significantly too shallow bedrock estimations. Therefore, we argue that both methods should be evaluated carefully and – wherever possible – should be combined to a comprehensive dataset. Since geotechnical investigations are one-dimensional and seismic measurements are areal, they provide complementing information that can be used to reduce errors.

This paper proposes a method for identifying critical vessels within offshore wind farm (OWF) areas based on complex network analysis. The method aims to identify high-risk or influential vessels by treating vessels and the wind farm vertices within these areas as nodes in network. The importance of each node is assessed using topological metrics, including Vertex Strength (VS), Degree Centrality (DC), Clustering Coefficient (CC), and Betweenness Centrality (BC). To obtain a comprehensive ranking of vessel nodes, the entropy weight method and principal component analysis (PCA) are employed. This ranking helps identify the vessels that have the most significant impact on the overall safety of OWF areas. The effectiveness of the proposed method is validated using real AIS data, demonstrating its capability in accurately identifying critical vessels in OWF areas.

Offshore wind climatology based on synergetic use of Envisat ASAR, ASCAT and QuikSCAT