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The airport at Northway was rendered unusable by lateral spreading. The
frozen surface layer and pavement runway were cut by fissures, many
10-30 cm wide, some more than a meter wide. On the perimeter of the
runway were large sand vents and sink holes up to 4 m in diameter and up
to 1 m deep. Reports from residents describe pressurized ground water
spewing out soil 2-4 m into the air. Parallel and polygon patterns
similar to those observed in the Tanana River bars were observed at
Northway. Away from the runway, houses and structures were unseated and
tilted on their foundations, and road settlements bent and crushed
drainage culverts.
click on image above for larger size
Widespread liquefaction and lateral spreading was observed at Fielding Lake, along the Richardson Highway, where the upper soil crust was not frozen during the earthquake. Seen here were classic features associated with lateral spreading along the lakeshore such as large fissures, spreading cracks, and slumping.
click on image above for larger size
Structures on the spreading ground were deformed and displaced, and an underground septic tank buoyed to the surface lifting a small structure.   click on image above for larger size |
