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This report presents the new seismic hazard maps for the UK offshore Exclusive Economic Zone (EEZ) developed using a Monte Carlo-based approach. These are intended to update the current maps for UK waters published in 2002. The work done by the BGS team in this project has been informed at key stages by external experts who have reviewed the main components of the seismic hazard model. The analysis is based on a comprehensive catalogue of earthquake activity across the region developed by combining existing earthquake catalogues and data from regional and local monitoring agencies. Anthropogenic events such as those related to blasting, underwater explosions, mining and hydrocarbon exploration have been removed where possible. We also remove foreshocks and aftershocks to ensure that the catalogue only contains time-independent events. We then use published empirical magnitude conversion relationships to convert different magnitudes to moment magnitude (Mw) to ensure that the catalogue has consistent and homogeneous magnitudes across the region of interest. Finally, we assess catalogue completeness for different time intervals using both published information for the earthquake catalogues from the region and by examining cumulative and annual numbers of earthquakes for specific magnitudes. We model earthquake occurrence across the region using a seismic source characterisation (SSC) model that consists of a series of zones, where seismicity is considered to be homogeneous. The shape and extent of each zone are based on knowledge of the tectonics, geology and seismicity of the study area. We use four different seismic source zone models within the SSC to capture the epistemic uncertainty in different rupture scenarios but we do not include specific fault sources in the SSC model because of the difficulty relating earthquakes to particular faults. We estimate the rate of earthquake occurrence for each seismic source zone using the earthquake catalogue derived for the s

Cold-water corals form substantial biogenic habitats on continental shelves and in deep-sea areas with topographic highs, such as banks and seamounts. In the Atlantic, many reef and mound complexes are engineered by Lophelia pertusa, the dominant framework-forming coral. In this study, a variety of mapping approaches were used at a range of scales to map the distribution of both cold-water coral habitats and individual coral colonies at the Mingulay Reef Complex (west Scotland). The new ArcGIS-based British Geological Survey (BGS) seabed mapping toolbox semi-automatically delineated over 500 Lophelia reef ‘mini-mounds’ from bathymetry data with 2-m resolution. The morphometric and acoustic characteristics of the mini-mounds were also automatically quantified and captured using this toolbox. Coral presence data were derived from high-definition remotely operated vehicle (ROV) records and high-resolution microbathymetry collected by a ROV-mounted multibeam echosounder. With a resolution of 0.35 × 0.35 m, the microbathymetry covers 0.6 km2 in the centre of the study area and allowed identification of individual live coral colonies in acoustic data for the first time. Maximum water depth, maximum rugosity, mean rugosity, bathymetric positioning index and maximum current speed were identified as the environmental variables that contributed most to the prediction of live coral presence. These variables were used to create a predictive map of the likelihood of presence of live cold-water coral colonies in the area of the Mingulay Reef Complex covered by the 2-m resolution data set. Predictive maps of live corals across the reef will be especially valuable for future long-term monitoring surveys, including those needed to understand the impacts of global climate change. This is the first study using the newly developed BGS seabed mapping toolbox and an ROV-based microbathymetric grid to explore the environmental variables that control coral growth on cold-water coral reefs.

Pockmarks are indicators of focused fluid seepage, most notably gas such as methane, and can occur in vast numbers in many marine and even in lacustrine environments. The presence and distribution of pockmarks need to be considered in the development of any infrastructure at the seabed. However, manual mapping of these features can be extremely time-consuming and it is implicitly subjective. An extensive area in the central North Sea, where the seabed comprises a thick sequence of muds and sandy muds of the late glacial Witch Ground Formation, shows numerous inactive pockmarks, typically 20-100 m diameter and 3-4 m deep. Within this area a few larger, active pockmarks, 500 m diameter and up to 17 m deep are known. Modern site investigations in this area regularly include multibeam sonar mapping, a technique that collects large volumes of bathymetric data that can be used to produce digital depth models of the seafloor with sufficient resolution to characterize individual pockmarks. This paper presents a semi-automated method to recognize, spatially delineate and characterise morphometrically pockmarks at the seabed. The method comprises two scripts, Pockmark Mapping and Pockmark Characterization, that allow the systematic application of a sequence of well defined tools available within the ESRI ArcGIS toolbox. Almost 4150 pockmarks were mapped applying this method to 18 selected site surveys across the central North Sea. The mapping and morphometric characterization of such vast number of pockmarks allows the identification of certain trends reflecting the hydrodynamic regime, whereas the pockmarks density and spatial distribution appears to be attributable to differences in shallow gas availability and deeper geology controlling fluid migration pathways.

This report describes a geomorphological interpretation of a multibeam echosounder dataset acquired offshore Northern Ireland, between Belfast Lough and the town of Cushendun. It is part of a Department of Enterprise, Trade and Investment (DETI) sponsored study aimed at gaining a better understanding of the distribution and thickness of subsurface salt layers expected to be present offshore Northern Ireland with the aim of assessing their potential for construction of caverns for storage of natural gas. Part of the study involved the acquisition of a high resolution 2D seismic dataset designed to image potential Upper Permian and Middle Triassic salt layers. The multibeam dataset was acquired in conjunction with the 2D seismic dataset and, despite this being a lower priority deliverable, good coverage was achieved due to the high density of seismic tracks and relatively deep water depth in this nearshore location. The multibeam data provides accurate measurements of the water depth in the study area and valuable information about the morphology and composition of the sea bed in the area. In the southern part of the survey area almost 100% coverage was achieved because of the close line spacing whereas in the northern part there are gaps between the multibeam data swaths. Although not specifically designed to acquire data to Admiralty Chart standard nonetheless the survey has made a valuable contribution to the knowledge of the seabed in this area which has applications in navigation, fishing, marine conservation and planning. The multibeam dataset, comprising bathymetric and backscatter information, was interpreted using ArcMap 9.3 GIS software. This allowed the use of appropriate surface analysis tools, such as slope and shaded-relief, to enhance the geomorphological interpretation. It also allowed the integration of the multibeam with other datasets held by the British Geological Survey (BGS). The multibeam dataset reveals the complex morphology of the surveyed se

The Holocene Storegga Slide is one of the world’s largest exposed slides and also the most studied of all the Norwegian slides. However due to its complexity it is far from being fully understood. Three-dimensional (3D) seismic combined with swath bathymetry data from the southern flank of the Storegga Slide have been used to study mass movement processes occurring in the region. The high spatial resolution provided by the 3D seismic data has allowed a detailed geomorphological analysis of sedimentary and deformational structures. The Holocene Storegga failure affected a significant part of the studied area. The predominant feature is a compression zone, comprising two lobes, where the seabed shows marked parallel ridges. Down slope it is possible to identify another compression zone. A relative chronology of events was established and it is proposed that these two compressions zones are the result of gravity-driven slope failures related to different stages of the Holocene Storegga Slide.

This report updates the ‘Two-part Seabed Geomorphology classification scheme’ of Dove et al. (2016) and presents a new glossary (Part 1) of Seabed Morphology features. This Morphology glossary is intended to provide marine scientists with a robust and consistent way to characterise the seabed. Each glossary entry includes a feature definition and a representative schematic diagram to support clear and accurate classification. Feature terms and definitions are primarily drawn from the International Hydrographic Organization (IHO) guide for undersea feature names, which are herein modified and augmented with additional terms to ensure the final feature catalogue and glossary encompasses the diversity of morphologies observed at the seabed, while also minimising duplication and/or ambiguity. This updated classification system and new glossary are the result of a collaboration between marine geoscientists from marine mapping programmes/networks in Norway (MAREANO), Ireland (INFOMAR), UK (MAREMAP), and Australia (Geoscience Australia) (MIM-GA). A subsequent report will present the (Part 2) Geomorphology feature glossary

This report updates the ‘Two-part Seabed Geomorphology classification scheme’ of Dove et al. (2016) and presents a new glossary (Part 1) of Seabed Morphology features. This Morphology glossary is intended to provide marine scientists with a robust and consistent way to characterise the seabed. Each glossary entry includes a feature definition and a representative schematic diagram to support clear and accurate classification. Feature terms and definitions are primarily drawn from the International Hydrographic Organization (IHO) guide for undersea feature names, which are herein modified and augmented with additional terms to ensure the final feature catalogue and glossary encompasses the diversity of morphologies observed at the seabed, while also minimising duplication and/or ambiguity. This updated classification system and new glossary are the result of a collaboration between marine geoscientists from marine mapping programmes/networks in Norway (MAREANO), Ireland (INFOMAR), UK (MAREMAP), and Australia (Geoscience Australia) (MIM-GA). A subsequent report will present the (Part 2) Geomorphology feature glossary