Pacific Coastal & Marine Science Center Coastal and Marine
Earthquake Studies |The Cascadia Megathrust and Tectonic Stress
in the Pacific Northwest To understand the tectonic cause of
stress and deformation in the Pacific Northwest, we need to
consider not only forces acting along the Cascadia Subduction
zone, but also forces acting along the tectonic margins to the
north (Queen Charlotte fault) and to the south (San Andreas
fault). In addition, over millions of years, mountain ranges are
built that locally affect stress and deformation within the
North American plate (i.e., internal forces in diagram at
right). In general, the present day state of stress depends, in
part, on how the continent was deformed in the past. In other
words, the present-day rate of deformation has a "memory" of
past deformation episodes. As one might be lead to believe from
the previous discussion, modeling the deformation of continents
is very complex. The model chosen for this study (LARAMY) was
developed over several years by Dr.