Glacial isostatic adjustment, relative sea level history and mantle viscosity: reconciling relative sea level model predictions for the U.S. East coast with geological constraints

Holocene Relative Sea-Level Changes from Near-, Intermediate-, and Far-Field Locations

“…These locations experience rates of present-day RSL rise in the higher Rate of relative sea-level change Fig. 1 Current rates of relative sea-level (RSL) change from glacio-isostatic adjustment (GIA) predicted using ICE-6G_C (VM6) model [20]. The color scheme denoting rates of RSL change was chosen to remain consistent with previous GIA modeling studies from the University of Toronto range of intermediate-field sites (Fig 1).…”

“…This transfer of mass from land ice to the global ocean both increased ocean volume and triggered a large, ongoing isostatic response of the solid Earth [4,13,18,19]. The present-day rate of RSL rise due to GIA varies among near-, intermediate, and far-field regions (Fig 1) [20]. In near-field regions (i.e., areas located beneath continental ice sheets at the LGM), the rate of glacio-isostatic uplift during deglaciation exceeded the rate of eustatic (land ice volume and thermal expansion) sea-level rise, resulting in RSL records characterized by continuous RSL fall (Fig 2).…”

On the reconstruction of palaeo-ice sheets: Recent advances and future challenges

“…The VM2 viscosity profile of the ICE-5G model, and the simple multilayer fit to this profile provided by the VM5a model in ICE-6G_C (VM5a), provides an excellent fit to the majority of the GIA-related observations. In the most recent work, however, a further refinement to this viscosity profile has been shown to be necessary to incorporate the additional constraints provided by relative sea level history data from the region of postglacial forebulge collapse outboard of the LIS along the eastern and western seaboards of the continental United States (Roy and Peltier, 2015). Thus, the process of model improvement is an iterative one in which one starts with an assumed known depth variation of mantle viscosity determined on the basis of observations that are relatively independent of the thickness of glacial ice that, when removed during deglaciation, was responsible for inducing the time dependent uplift of the land that is recorded in radiocarbon-dated RSL histories.…”

The Role of Holocene Relative Sea-Level Change in Preserving Records of Subduction Zone Earthquakes

“…Progressive melting of the ice led to the collapse of this forebulge (glacioisostatic subsidence) as mantle material returned to the former load centers [33]. In intermediate-field regions (e.g., US Atlantic and Pacific coasts), isostatic and eustatic effects worked in tandem to produce rapid RSL rise up to ∼7 ka BP [34].…”