Ta. Heinrichs et al., QUIESCENT-PHASE EVOLUTION OF A SURGE-TYPE GLACIER - BLACK-RAPIDS GLACIER, ALASKA, USA, Journal of Glaciology, 42(140), 1996, pp. 110-122
Black Rapids Glacier, a surge-type glacier in the Alaska Range, most r
ecently surged in 1936-37 and is currently in its quiescent phase. Mas
s balance, ice velocity and thickness change have been measured at thr
ee to ten sites from 1972 to 1994. The annual speed has undergone cycl
ical fluctuations of as much as 45% about the mean speed. Ice thicknes
s and surface slope did nor change enough to cause the speed fluctuati
ons through changes in ice deformation, which indicates that they are
being driven by changes in basal motion. The behavior of Black Rapids
Glacier during this quiescent phase is significantly different from th
at of Variegated Glacier. another well-studied surge-type glacier in A
laska. The present medial-moraine configuration of Black Rapids Glacie
r indicates that a surge could occur al any time. However, ice velocit
y data indicate that the next surge may not be imminent. We believe th
at there is little chance that the next surge will cross and dam the D
elta River.