Current Geohazard Problems and Their Geophysical Interpretation- An International Overview

摘要

We present a selective review of geohazards that haverninfluenced recent offshore development projects. Thernexamples have been chosen to show how recent developmentsrnin geophysical interpretation have addressed the problemsrnposed by various types of geohazards. Three types ofrngeohazards are considered: environmental issues, geohazardsrnaffecting sub-sea foundation design and deepwaterrngeohazards. Environmental issues may not be conventionallyrnregarded as "geo" hazards; however, many environmentalrnissues present significant constraints on offshorerndevelopments and must be treated in the same way asrntraditional geohazards. They are features of, or on, the seabed,rnwhich must be located, mapped and characterised so that theyrncan be avoided or mitigated. Examples include coral reefs,rnherring spawning grounds, algal mats and many other types ofrnbenthic biology. Geohazards affecting sub-sea foundationrndesign are relatively well known (shallow channels, lateralrnvariations in soil properties, hardgrounds etc.) and there hasrnbeen a progressive improvement in the geophysicalrninterpretative methods available to characterise these hazards.rnDeep-water geohazards have been widely discussed and thernrange of hazards that may be encountered is widelyrnappreciated, but there is still scope for new surprises. Ourrnexamples show how geophysical interpretation canrncharacterise some of the major hazards such as sloperninstability, complex topography and mud volcanoes.rnDevelopments in geophysical interpretation include increasingrnuse of digital processing and interpretation of "analogue"rndatasets, use of seismic velocities to characterise soil types,rntight integration of geophysical and geotechnical datasets,rninterpretative use of visualisation software.