Figure 4. 1994 aerial photographs of ERF

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4

infrared).

lar to that found near the Portage area of

other factors, most of which lie beyond the scope

of our analysis. In particular, tectonic, and espe-

Turnagain Arm (Ovenshine et al. 1976a). Since

cially earthquake, activity is virtually impossible

the earthquake, the region has been rising at about

1.5 cm/year, although the rate has been decreas-

to predict; however, its impact on the physical

system of ERF may be enormous.

ing over time (Brown et al. 1977).

Eagle River Flats was last severely struck by

How the physical system responded to these

the 1964 Alaskan Earthquake (magnitude 9.2 on

changes in elevation is unknown; however, an

the Richter Scale [Cohen et al. 1995]), with both

increase in pond water depths may have resulted

in an increase in sedimentation rates, in keeping

sedimentary and tectonic subsidence affecting the

with what happened in Turnagain Arm (Oven-

site's elevation (Small and Wharton 1969) and

shine et al. 1976a). In addition, after the elevation

thus its physical processes. A tectonic drop of

drop, the tidal flat hydrology would be out of

about 0.60.7 m was recorded in the Anchorage

equilibrium, bringing a response from the physi-

region (Brown et al. 1977). Subsidence caused by

sediment liquefication and solidification probably

cal system. Disequilibrium would have been main-

reduced the pond elevations by an amount simi-

tained by the uplift following the earthquake.