A.V. AMANTOV (VSEGEI), L.M. CATHLES (Cornell University), M.G. AMANTOVA (VSEGEI)

Crustal subsidence caused by urban development: a component of geological hazard in the Saint-­Petersburg region

Surface loading resulted from intense urban development of coastal areas can cause minor land subsi­dence and relative sea level rise. The subsidence strongly depends on physical properties of the lithosphere, asthenosphere, and mantle, as well the loading and its change rate. The magnitude and area of the urban surface load over time were assessed for one possible scenario of urban expansion in the Saint­Petersburg region (2020–2120) with a preliminary estimation of the potential impact. The immediate elastic response and further isostatic subsidence caused by the urban loading can accelerate future flooding of the lowest coastal regions such as the Saint­Petersburg metropolitan area, and thus represent an additional geological hazard. The rate and magnitude of the elastic and isostatic depression are disputable, since they depend on different estimates of elastic properties and the effective elastic thickness of the lithosphere respectively.
Keywords: geologic hazards, geodynamics, isostasy, urban development, Holocene, coastal zone.