Geological causes of recent (~100 yr) vertical land movement in the Netherlands

Abstract

Geodetic levelling data record differential vertical movements of the top of the Pleistocene sands of up to 1.5 mm/year in the Netherlands over the last century. We compare these movements to (a) mean tectonic, isostatic and compaction movements at time scales of millions of years obtained by backstripping of Cenozoic stratigraphy, and (b) estimates of recent (~100 yr) movements from process modelling of isostasy (glacio- and hydro-isostasy) and compaction. The process rates at time scales of millions of years are insufficient to account for the geodetic observations by an order of magnitude. The isostasy and compaction rates inferred for the last century are also insufficient; they explain less than half of the observed movements. This suggests that the residual - observed rates less isostacy and compaction estimates - which is interpreted to represent tectonic crustal deformation, constitutes an important contribution to present-day movements. The surprisingly high rates of short-term tectonic vertical movements in a region which is relatively inactive, seismically, indicate that correction of tide-gauge records for the glacio-isostatic signal alone does not yield an appropriate measure of eustatic sea-level rise along the Dutch coast. Show more