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Full-Text Articles in Geology
Potential For Coastal Flooding Due To Coseismic Subsidence In The Central Cascadia Margin, Elson T. Barnett
Potential For Coastal Flooding Due To Coseismic Subsidence In The Central Cascadia Margin, Elson T. Barnett
Dissertations and Theses
Interpretations made from compilation of existing core and cutbank data for Oregon and Washington are used to evaluate the potential flooding impact from regional coseismic subsidence. Estimates of regional subsidence are based on tidal level indicators including plant macrofossils, peat development, and diatoms. A compilation of existing late Holocene stratigraphic records shows multiple burial events in all bays of Oregon, however some coastal sites in central Oregon show continuous submergence. Tests of tidal level indicators using modern Cascadia wetlands indicate that paleosubsidence can be estimated to 0.0 ± 0.5m, 1.0 ±0.5m, and 2 m ± 0.5m. An AMS date from …
Beach Response To Subsidence Following A Cascadia Subduction Zone Earthquake Along The Washington-Oregon Coast, Debra Lee Doyle
Beach Response To Subsidence Following A Cascadia Subduction Zone Earthquake Along The Washington-Oregon Coast, Debra Lee Doyle
Dissertations and Theses
Beach shoreline retreat induced by coseismic subsidence in the Cascadia subduction zone is an important post-earthquake hazard. Sand on a beach acts as a buffer to wave attack, protecting dunes, bluffs and terraces. The loss of sand from a beach could promote critical erosion of the shoreline. This study was initiated in order to estimate the potential amount of post subsidence shoreline retreat on a regional scale in the Central Cascadia Margin. The study area is a 331 km stretch of coastline from Copalis, Washington to Florence, Oregon. Several erosion models were evaluated, and the Bruun model was selected as …
Coastal Crossing Of The Elastic Strain Zero-Isobase, Cascadia Margin, South Central Oregon Coast, Gregory George Briggs
Coastal Crossing Of The Elastic Strain Zero-Isobase, Cascadia Margin, South Central Oregon Coast, Gregory George Briggs
Dissertations and Theses
The analysis of marsh cores from the tidal zones of the Siuslaw, Umpqua, and Coos River systems on the south-central Oregon coast provides supporting evidence of coseismic subsidence resulting from megathrust earthquakes and reveals the landward extent of the zero-isobase. The analysis is based on lithostratigraphy, paleotidal indicators, microfossil paleotidal indicators, and radiocarbon age. Coseismic activity is further supported by the presence of anomalous thin sand layers present in certain cores. The analysis of diatom assemblages provides evidence of relative sea-level displacement on the order of 1 to 2 m. The historic quiescence of local synclinal structures in the Coos …