The amount of tectonic uplift on Glacier Island in Prince William Sound was shown by the upper limit to which algae of the intertidal zone are on this sea cliff before and after the earthquake. The top of the band of green (still living) algae is near present post- earthquake) mean high tide. The top of the band of brown (desiccated) algae marks the approximate position of mean high tide before the earthquake. The difference in height between the top of the bands of living and of desiccated algae (3 feet) is a measure of the amount of tectonic uplift in this area.
These spruce trees on a gravel spill on Resurrection Bay on the Kenai Peninsula are in an area which tectonically subsided 3 feet during the earthquake. The subsidence dropped the shallow roots of these trees below high tide, where they were killed by repeated inundation in salt water.
The village of Portage, at the head of Turnagain Arm of Cook Inlet, is now flooded at high tide as a result of 6 feet of tectonic subsidence during the earthquake.
The Hanning Bay fault was reactivated during the earthquake. Its trace is marked by a ten- to 15-foot high bedrock scarp which trends obliquely across the field of view from the right foreground to the left background. The fault trace lies between the uplifted wave-cut surface that is coated white by desiccated calcareous marine organisms and borders the open ocean and the area of brown sand and silt in the cove. The ground northwest of the fault (on the right) was displaced upward as much as 16 feet with respect to the ground southeast of the fault during the earthquake, but both sides of the fault were uplifted with respect to sea level due to general tectonic uplift of the region. The fault plane dips steeply northwest or is vertical. View is southwest along the Hanning Bay fault scarp on southwest Montague Island in Prince William Sound.
Hanning Bay fault scarp on Montague Island, looking northwest. Vertical displacement in the foreground, in rock, is about 12 feet. The maximum measured displacement of 14 feet is at the beach ridge near the trees in the background.