LAUSR

Abstract We present a comprehensive view of the origin, significance and implications of topographic effects in gravimetry. These are gravitational effects of topographic masses that are present in any observable quantity of the earth's gravitational field. In most gravimetric applications and their computational realizations, when topography is not the focus of the study, these effects need to be properly treated as corrections (reductions). Some of them might not be obvious or intuitive, and may remain misunderstood and mistreated. First, we look at topographic effects in geodesy and focus on those that affect the determination of the geoid from terrestrial gravity data. We review the origin and role of both the direct and indirect, the primary and secondary topographic effects. Then, we review the Bouguer concept in geophysical applications. Finally, we take a look at the topographic effect induced by the deformation of the topographic surface and its importance in the interpretation of observed spatiotemporal gravity changes. We illustrate the sizes and shapes (spatial properties) of these effects, discuss their relevance and impacts in the areas of geodesy, geophysical structural studies (exploration and prospection), and in geodynamics with a focus on volcano geodesy.