HR: 17:15h
AN: G44A-06    [Abstracts]
TI: Spatial Variations of Subsidence, Uplift, and Sea-level Rise in Western Canada and Northwestern U.S.: Implications for Coastal Communities
AU: * Mazzotti, S
EM: smazzotti@nrcan.gc.ca
AF: Geological Survey of Canada, Natural Resources Canada, 9860 West Saanich Rd, Sidney, BC V8L 4B2, Canada
AU: * Mazzotti, S
EM: smazzotti@nrcan.gc.ca
AF: School of Earth and Ocean Sciences, University of Victoria, P.O. Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
AU: Jones, C
AF: School of Earth and Ocean Sciences, University of Victoria, P.O. Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
AU: Thomson, R
AF: Institute of Ocean Sciences, Fisheries and Oceans Canada, P.O. Box 6000, Sidney, BC V8L 4B2, Canada
AU: Lambert, A
AF: Geological Survey of Canada, Natural Resources Canada, 9860 West Saanich Rd, Sidney, BC V8L 4B2, Canada
AU: Stephenson, F
AF: Institute of Ocean Sciences, Fisheries and Oceans Canada, P.O. Box 6000, Sidney, BC V8L 4B2, Canada
AU: Mate, D
AF: Geological Survey of Canada, Natural Resources Canada, 9860 West Saanich Rd, Sidney, BC V8L 4B2, Canada
AB: Sea-level rise in the Northeast Pacific Basin is a significant source of hazard to the coastal urban centers and infrastructures in western Canada and northwestern U.S. Crustal vertical motions, and hence relative sea-level (RSL), are expected to vary considerably across the 2000 km-long coast as a result of spatial variations in active tectonics and Holocene post-glacial rebound. Thus, tide gauge data from this region has so far been rejected from most global analyses to avoid the effects of uncorrected vertical motions. Recent studies suggest large spatial variations in the 20th Century rates of sea-level rise raising the issue of applicability of global mean eustatic estimates to the Northeast Pacific Basin. To address this question, we analyze a subset of about 35 collocated or nearly located continuous GPS and tide gauge sites. Data from Canadian and U.S. tide gauges are quality controlled, filtered, and corrected for common seasonal and inter-annual signals to derive robust RSL trends. In particular, we estimate linear trends and associated standard errors that account for the spatially and temporally correlated characteristics of the RSL data. Vertical velocities at the GPS sites are derived in the ITRF2000 reference frame. Alternative reference frames (e.g., IGb00, ITRF2005) and other GPS-specific scale issues are considered as part of the overall uncertainties in the absolute GPS vertical velocities. The combined tide gauge/GPS analyses indicate a 20th Century Northeast Pacific rate of sea-level rise of 1.5-2.0 mm/yr, in good agreement with global average eustatic estimates. Based on our assessments of coastal vertical motions from GPS and tide gauge data, we derive maps of predicted RSL rise over the next 50 and 100 years in western Canada and northwestern U.S. Large-scale sea-level rise predictions are based on IPCC scenarios, but the main factors controlling the spatial RSL patterns are the uplift and subsidence variations along the coast. In particular, we show that tectonic and sediment-loading subsidence in the Puget Lowland-Strait of Georgia area have the potential to significantly aggravate the predicted RSL rise in Greater Vancouver and Seattle-Tacoma. Conversely, tectonic uplift along parts of the west coast can compensate for about half of future sea-level rise.
DE: 1222 Ocean monitoring with geodetic techniques (1225, 1641, 3010, 4532, 4556, 4560, 6959)
DE: 1295 Integrations of techniques
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 4217 Coastal processes
SC: Geodesy [G]
MN: 2007 Fall Meeting