gradient known as the Dewatto lineament. It arises from the contrast between the denser and more magnetic basalt of the Crescent Formation that has been uplifted to the east, and the glacial sediments that have filled the Dewatto basin to the west. The Dewatto linement extends from the western end of the Tacoma fault (see map immediately above) northward towards Green Mountain at the western end of the Seattle fault. Kinematic analysis suggests that if shortening (compression) in the Puget Lowland is directed to the northeast (i.e., parallel to Hood Canal and the Saddle Mountain deformation zone) and thus oblique to the Dewatto lineament, it should be subject to both strike-slip and dip-slip forces, implying a fault. Recent geophysical modeling suggests that the Dewatto lineament is the expression of a blind (concealed), low-angle, east-dipping thrust fault, named the Dewatto fault. (Originally named the Tahuya Fault.) This reflects westward thrusting of the Seattle Uplift into the Dewatto basin, a northwestern extension of the Tacoma basin. This interpretation suggests that the Seattle Uplift acts as a rigid block, and possibly explains the kinematic linkage by which large earthquakes may involve ruptures on multiple faults: the Seattle, Dewatto, and Tacoma faults represent the northern, western, and southern faces of a single block. Such interconnection also suggests a capability for larger earthquakes (> M7 for the Seattle Fault); the amount of increased risk is unknown. Hood Canal Fault Hood Canal marks an abrupt change of physiography between the Puget Lowland and the Olympic Mountains to the west. Based on this and geophysical anomalies it was inferred that there is a major, active strike-slip fault zone running from the south end of Hood Canal, up Dabob Bay, and continuing north on land. This is conformable with some regional tectonic interpretations that put a major terrane boundary between the Olympics and the Puget Lowland, and imply a connection (either via the Discovery Bay Fault, or closer to Port Townsend) to the various faults in the Strait of Juan de Fuca. This boundary would be the contact where northward movement of the basement rock of the Puget Lowland against the Olympic Peninsula is accommodated; it would be expected to be a significant seismological zone. However, the Hood Canal fault has been "largely inferred" due to a paucity of evidence, including lack of definite scarps and any other signs of active seismicity. A 2001 study using high-resolution seismic