T182 Living on the Edge: Deformation along the Cascadia Margin (Posters)

Tuesday, 20 October 2009
9:00 AM - 6:00 PM
Hall A

ATLAS OF ACTIVE SHALLOW TECTONIC DEFORMATION IN THE PUGET LOWLAND, WASHINGTON

Paper number: T182-1
Program: Technical Sessions
Time: 9:00 AM – 6:00 PM

Authors

Abstract

This atlas presents an up-to-date map compilation of the growing set of geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow Lowland faults are mapped where observations of deformation from paleoseismic, seismic reflection, and potential-field investigations converge. Together, results from these studies bolster the identification and characterization of regional faults and show that as many as a dozen shallow faults were active during the Holocene.
The suite of maps presented in our atlas identifies sites with evidence of deformation attributed to these shallow faults. For example, one map shows the locations of field evidence for coseismic surface rupture or deformation as determined from paleoseismic investigations of features such as fault scarps and deformed shorelines. Other maps compile the locations of seismic reflection and potential-field studies that have shown evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from and draped over the data sets presented in the preceding maps. Overall, the atlas provides map-users with a visual overview of the observations and interpretations that support the existence of active,shallow faults beneath the densely populated Puget Lowland.