Dashed lines are faults known from geologic mapping. Note the strong magnetic lineation parallel to both the Portland Hills fault and the East Bank fault. The magnetic patterns confirm the existence of the East Bank fault and suggests that it may be more dangerous than previously suspected. Scientists believe that the East Bank fault, the Portland Hills fault, and other northwest-southeast trending faults in the Portland metropolitan area are part of a broad zone of faulting, called the Portland Hills fault zone. If seismically active along its entire length, the Portland Hills fault zone poses a more significant seismic hazard to the Portland-Vancouver community than previously suspected.
Scene is viewed from the southeast, with topography vertically exaggerated.
Because of the success of the 1992 airborne magnetic study, the U.S. Geological Survey conducted a similar program in 1995. This new airborne study continued south from the Portland-Vancouver survey to include the cities of Salem, Woodburn, and Mt. Angel. Or contact any one of the co-investigators directly.