Havbunnsgroper

Havbunnsgroper, or seabed depressions, are natural pits or hollows on the floor of the ocean. They occur in many marine environments, from shallow shelves to deep-sea basins, and can vary in size, shape, and relief. The term describes a range of features, including circular or elongated hollows and pockmark-like formations.

A primary mechanism in their formation is submarine gas seepage, where escaping gas and fluids destabilize sediments and cause round, cup-shaped depressions. Other processes also contribute, such as erosion by bottom currents, turbidity flows, sediment compaction and subsidence related to tectonic activity, and biological effects from burrowing organisms that shape the seafloor over time.

Havbunnsgroper differ in morphology and scale. They can range from a few meters to tens of meters across and may present as relatively shallow or pronounced relief features. They are commonly found on continental margins and in regions with dynamic sedimentation, gas hydrate systems, or hydrocarbon seepage, but they also occur in other marine settings worldwide.

Ecologically, these depressions can host specialized benthic communities. They may provide habitats for short-lived or unique assemblages of invertebrates, as well as microbial mats in certain seepage areas. The edges and interiors of the pits influence nutrient flow, sediment deposition, and local biodiversity.

Mapping and study of havbunnsgroper rely on sonar surveys, including multibeam and side-scan sonars, as well as sub-bottom profiling and, where possible, direct observations with remotely operated or autonomous vehicles. Their presence can indicate subsurface processes and, in some contexts, hydrocarbon seepage, with implications for marine geology, ecology, and offshore engineering.