Norwegian Geotechnical Institute (NGI) Digital Archive
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Deliverable 2.4 Updated catalog and focal mechanism database
No full textThis report describes updates to the North Sea seismicity event bulletin in which all earthquakes from databases of the countries bordering the North Sea are amalgamated into a single bulletin. This is the first dataset of its kind and makes up the most complete and homogeneous bulletin for the North Sea at the time. A comprehensive evaluation of the natural earthquake activity provides important information on the stress field and faulting mechanisms near the proposed reservoirs for carbon capture sequestration. The collected information is crucial for the understanding of the response of the reservoir and caprock to large-scale fluid injection. This deliverable describes the subsequent analysis comprised of event magnitudes, locations, and moment tensor inversion to derive source mechanisms.
SHARP’s North Sea earthquake bulletin is updated from the earlier produced bulletin presented in deliverable D2.1. The new bulletin comprises mostly the removal of explosion events and minor formatting issues and constitutes the most complete and - despite unresolved challenges - the most homogeneous representation of North Sea seismicity available to date. Two byproducts of the new bulletin are a catalogue consisting of prime information and a catalogue extended to a larger region as base for the seismic hazard analysis performed in WP 5. Furthermore, analyses are performed on different magnitude scales. The usage of different formulas and input data makes direct comparisons between magnitudes difficult, especially for the local magnitudes. An analysis is also performed to relocate events within the North Sea bulletin, making use of the abundance of the new compilation of phase information. Our effort now also includes collecting waveforms for events that occurred later than 1990 and had magnitudes larger than M 3.5, although quality control of these waveforms was not possible yet. Lastly, previously computed focal mechanisms are collected, and new moment tensors are calculated mainly for the larger magnitude events. We conclude that for many events, the number of available records as well as the data quality is not sufficient for reliable estimates of, e.g., source mechanisms.
Therefore, our main recommendation is to install more offshore seismic stations, particularly to add stations close to potential sources to increase the number of near-source observations and fill the azimuthal gaps in the station’s coverage to enable a more precise event location, event depth estimates and source mechanism analysis as well as enhance magnitude estimates. Especially with a view on the start up of CO2 injection and storage, it is important to establish a more reliable event analysis specifically for lower magnitude events that may potentially be induced events during operations. Without a dedicated plan to install a larger number of stations within the North Sea, a stable event analysis and derivation of estimates of stress orientations remain only possible for the largest magnitude event, not to mention the impossibility of a discrimination of natural and induced seismicity.European CommissionpublishedVersio
Passive sampling in support of biota monitoring of hydrophobic substances under the Water Framework Directive
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Deliverable 4.3 Machine learning approaches for earthquake detection
Full text linkThis report is a review of machine learning-based methods for earthquake detection. It first introduces the basic concepts of traditional earthquake detection, and commonly used approaches. It then goes onto describe the concept of artificial intelligence, machine learning, and deep learning. This is followed with a summary of how these concepts are employed to detect earthquakes in seismic data, with a synthesis of the most widely used machine learning detection algorithms. The ways in which machine learning methods could be applied to the activities in the SHARP project are given in the conclusions, along with the future directions of the field.European CommissionpublishedVersio
Data-augmented landslide displacement prediction using generative adversarial network
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Progress in European chemicals policy to support the protection of the environment and human health from persistent, mobile and toxic and very persistent and very mobile substances
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Under ballast mats as mitigation measure for structure borne noise from railroad – assessment of effect on track deflection
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Anchor chain profiles in sand based on centrifuge model tests
Full text linkThe rapid development of floating wind turbines (FWTs) has brought new challenges to their mooring systems in shallow water of 50-200 m. The sand seabed, which is widely distributed in offshore regions, is often encountered in the service of FWTs and influences the anchor and mooring line design. The anchor chain is primarily adopted as the part interacting with the seabed, and its configuration in the seabed is vital for anchor design. However, a complete understanding of the chain configuration in sand is yet to be achieved. To address this, a group of centrifuge model tests using a model chain were conducted to simulate the chain embedment behavior in carbonate sand. During the tests, the chain position and soil deformation were captured using the Particle Image Velocimetry (PIV) method. A calculation model was adopted to predict the chain configuration in the sand, compare it with the centrifuge test results, and then analyze the differences between them. Finally, suggestions for model improvement were discussed.Anchor chain profiles in sand based on centrifuge model testspublishedVersio
