Potential fields and subsurface models of Suvasvesi North impact structure, Finland

The Suvasvesi North (N) impact structure, central-east Finland, has a diameter of about 3.5 km. It is covered by Lake Suvasvesi and lacks a topographic or bathymetric rim. The structure has a pronounced geophysical response, i.e. gravity, magnetics and electromagnetics. It is characterised by a ∼3.5 km wide negative Bouguer gravity anomaly of 5.5 mGal. The impact-related anomaly is about 2.8 mGal whereas regional geological features, water, and post-impact Quaternary sediments produce the difference. The physico-chemical processes due to the impact event have reduced and smoothed the airborne magnetic anomalies at the crater area. A small and intensive circular negative anomaly of ∼160 nT in amplitude and ∼0.8 km in diameter has been drilled and proven to be caused by impact melt. This central magnetic anomaly nearly coincides with the distinct bathymetric depth maximum (ca. 90 m). The Suvasvesi lake and Suvasvesi N structure are characterised also by electromagnetic anomalies. This article presents the potential fields, subsurface models, and an age estimate of the Suvasvesi N impact structure.