Russell Fiord Research Articles

Uplift and exhumation of the Russell Fiord and Boundary blocks along the northern Fairweather transform fault, Alaska

Uplift and exhumation of the Russell Fiord and Boundary blocks along the northern Fairweather transform fault, Alaska

Glaciological and marine geological controls on terminus dynamics of Hubbard Glacier, southeast Alaska

Hubbard Glacier, located in southeast Alaska, is the world's largest nonpolar tidewater glacier. It has been steadily advancing since it was first mapped in 1895; occasionally, the advance creates an ice or sediment dam that blocks a tributary fjord (Russell Fiord). The sustained advance raises the probability of long-term closure in the near future, which will strongly impact the ecosystem of Russell Fiord and the nearby community of Yakutat. Here, we examine a 43 year record of flow speeds and terminus position to understand the large-scale dynamics of Hubbard Glacier. Our long-term record shows that the rate of terminus advance has increased slightly since 1895, with the exception of a slowed advance between approximately 1972 and 1984. The short-lived closure events in 1986 and 2002 were not initiated by perturbations in ice velocity or environmental forcings but were likely due to fluctuations in sedimentation patterns at the terminus. This study points to the significance of a coupled system where short-term velocity fluctuations and morainal shoal development control tidewater glacier terminus position.

Seasonal fluctuations in the advance of a tidewater glacier and potential causes: Hubbard Glacier, Alaska, USA

AbstractSatellite imagery has been used to acquire seasonal terminus positions of tidewater Hubbard Glacier, Alaska, USA, from 1992 to 2006. During this 15 year time period, the width-averaged advance of the entire terminus has been ∼620 m at a mean rate of 35 m a−1. Seasonal fluctuation of the terminus ranges from 150 to 200 m on average and varies spatially. A section of the terminus, near a narrow gap where the glacier has now twice closed off 40 km long Russell Fiord, exhibited little to no mean advance during this time period but displayed seasonal fluctuations of 300–500 m. Seasonal variability in surface ice speeds and surface sea-water temperatures was also observed; both are potential forcing mechanisms for terminus fluctuations. Seasonal changes in sea-water temperature of 10–12°C, as well as seasonal changes in subglacial freshwater discharge, are inferred to influence calving and submarine melting at the terminus, driving seasonal variations. Displacements of the medial moraine separating Hubbard and Valerie Glaciers at the terminus suggest surge-like pulses of the latter, with a periodicity of several years. The timing of these pulses suggests they may influence the Hubbard terminus near Gilbert Point and have implications for future closures of Russell Fiord.

Hubbard Glacier update: another closure of Russell Fiord in the making?

Hubbard Glacier update: another closure of Russell Fiord in the making?

Holocene history of Hubbard Glacier in Yakutat Bay and Russell Fiord, southern Alaska

Stratigraphic and geomorphic data defined by radiocarbon ages, tree-ring dates, and historical observations provide evidence of three major Holocene expansions of Hubbard Glacier. Early in each advance the Hubbard Glacier margin blocked Russell Fiord to create Russell lake, raising base level and causing stream beds and fan deltas throughout the Russell drainage basin to aggrade. Each Hubbard Glacier expansion continued with an ice lobe advancing through Disenchantment and Yakutat Bays in the west, and an eastern lobe advancing into Russell Fiord. The earlier two Holocene expansions were, respectively, under way at 7690 and 5600 calibrated yr B.P., and each advance culminated more than 1 k.y. later. The late Holocene advance was under way by 3100 yr ago and reached ∼13 km farther south in Russell Fiord than the preceding two expansions. Late Holocene deglaciation of Yakutat and Disenchantment Bays was complete before A.D. 1791; Nunatak Glacier flowing from neves east of Russell Fiord became the primary ice source to the Russell Fiord lobe at or before this date. Ice retreat from the southern end of Russell Fiord began in the late eighteenth century and the penultimate Russell lake drained ca. A.D. 1860. The relatively slow advances and more rapid retreats of Hubbard Glacier are consistent with the model of the iceberg-calving glacier cycle. Hubbard Glacier is currently advancing and will likely reestablish Russell lake in the near future, affecting local fisheries. However, glacier lobes are unlikely to reach the area of the town of Yakutat, built on late Holocene glacial deposits, in the next 1 k.y.

Temperate Glacimarine Varves: An Example from Disenchantment Bay, Southern Alaska

ABSTRACT The sediment record of Disenchantment Bay, Southern Alaska, a large marine calving embayment, contains distinctive annual deposits. Each year a glacimarine couplet forms with a clast-rich stratified to massive diamicton deposited in winter by intense iceberg rafting and a summer, meltwater deposit of thinly laminated mud and turbidite sand beds. Although iceberg rafting occurs throughout the year, coarse debris is deposited in high concentrations and forms diamicton only during the winter because of minimal fine sediment from meltwater discharges and a longer residence time of icebergs in the Bay due to winter fjord circulation and meteorological factors. When meltwater discharge commences in summer, laminated mud with dropstones is deposited. Spring and fall conditions are recorded a transitional phases between winter and summer by clast-poor diamictons. Average sediment accumulation rates calculated from varve thicknesses range from 48 cm/yr, 3.4 km from Hubbard Glacier at the head of the Bay, to 14 cm/yr, 15 km away. Sediment accumulation rates estimated from 210Pb dating of core sediments are in the same range. Deposits from the 1986 Russell Fiord outburst flood are identified from anomalously high 210Pb activities in sediments indicating an alternative sediment source to Disenchantment Bay. Glacimarine varves are a dating tool for the barren proximal sediments commonly deposited near calving glacier termini. They yield paleoclimatic information because they are a product of both glacial ice in the sea and laminated sediments deposited from significant melt-water discharge found in a temperate to subpolar climate.

The marine record of the Russell Fiord outburst flood, Alaska, U.S.A.

The advance of Hubbard Glacier, near Yakutat, Alaska, U.S.A., in spring 1986 blocked the entrance to Russell Fiord with an ice-and-sediment dam, behind which a lake formed. The water level in Russell Lake rose to 25.5 m a.s.l. The dam catastrophically failed in October 1986, releasing 5.4 km3 of water into Disenchantment Bay. High-resolution seismic-reflection profiles show a 7.5 km long channel system cut into and buried by glacimarine sediment, represented by continuous, parallel reflections. The chaotic seismic facies filling the channel is interpreted to be debris flow deposits. A gravity core from channel-overbank deposits contained sandy diamicton with mud clasts. Above the channel a 1–2 m thick sediment drape extends across the bay. Laminated mud, fining-upward sand beds and diamicton were recovered from this unit. The sediment-drape deposits were produced by suspension settling from turbid plumes and non-channelized turbidity currents generated by the outburst flood.

The marine record of the Russell Fiord outburst flood, Alaska, U.S.A.

The advance of Hubbard Glacier, near Yakutat, Alaska, U.S.A., in spring 1986 blocked the entrance to Russell Fiord with an ice-and-sediment dam, behind which a lake formed. The water level in Russell Lake rose to 25.5 m a.s.l. The dam catastrophically failed in October 1986, releasing 5.4 km3of water into Disenchantment Bay. High-resolution seismic-reflection profiles show a 7.5 km long channel system cut into and buried by glacimarine sediment, represented by continuous, parallel reflections. The chaotic seismic facies filling the channel is interpreted to be debris flow deposits. A gravity core from channel-overbank deposits contained sandy diamicton with mud clasts. Above the channel a 1–2 m thick sediment drape extends across the bay. Laminated mud, fining-upward sand beds and diamicton were recovered from this unit. The sediment-drape deposits were produced by suspension settling from turbid plumes and non-channelized turbidity currents generated by the outburst flood.

Determination of Salmonid Smolt Yield with Rotary-Screw Traps in the Situk River, Alaska, to Predict Effects of Glacial Flooding

Abstract Hubbard Glacier is expected to dam Russell Fiord and cause glacial flooding of the lower 20 km of the Situk River near Yakutat, Alaska. To determine probable effects of the flooding on juvenile salmonids Oncorhynchus spp., two rotary-screw traps were used to estimate smolt yield inside and outside the predicted flood zone. Traps were fished from April to mid-August 1990: one at the predicted upstream limit of flooding and the other 3 km upstream from the river mouth. Every week, a sample of each salmonid species was tattoo-marked and released 1 km above each trap; recaptures were used to expand catches to estimate smolt yield. Trap efficiency ranged widely among species, from 3% for steelhead O. mykiss to 24% for chinook salmon O. tshawytscha. Estimated total smolt yields were 900,000 sockeye salmon O. nerka, 213,000 coho salmon O. kisutch, 67,000 chinook salmon, and 26,000 steelhead; only sockeye salmon (34% of this species' smolts) originated in the flood zone. Estimated mortality between traps...

The terminus of Hubbard Glacier, Alaska

Hubbard Glacier advanced across the entrance of Russell Fiord in May 1986, transforming the fiord into a lake, which began filling with fresh water. The dam failed in October 1986. The calving terminus of Hubbard Glacier has been mapped with increasing frequency for nearly a century. A mapping interval of a few years establishes that the terminus has made a slow, but accelerating, advance. Recently the terminus has been mapped several times per month using vertical photography, ground surveys, and time-lapse cameras. At this frequency of observation, the terminus position is found to fluctuate seasonally. These seasonal fluctuations are compared with those of Columbia Glacier, where a longer detailed record is available. Although Columbia Glacier is now undergoing a drastic retreat, it continues to have seasonal length changes similar to those it experienced before the retreat began. The lengths of both Columbia and Hubbard Glaciers are extended in the spring, and retracted in the fall. The relatively long period of record for Columbia Glacier shows consistent seasonal variation in length and, when compared with the short period of record for Hubbard Glacier, suggests that there are consistent seasonal differences in length at Hubbard also. The lower Hubbard Glacier diverges, feeding ice into Disenchantment Bay and Russell Fiord, and advances and retreats synchronously over most of its width. The tidal current, which passes through the 250–500 m wide entrance to Russell Fiord, does not affect the seasonal advance and retreat in that area significantly.

The terminus of Hubbard Glacier, Alaska

Hubbard Glacier advanced across the entrance of Russell Fiord in May 1986, transforming the fiord into a lake, which began filling with fresh water. The dam failed in October 1986. The calving terminus of Hubbard Glacier has been mapped with increasing frequency for nearly a century. A mapping interval of a few years establishes that the terminus has made a slow, but accelerating, advance. Recently the terminus has been mapped several times per month using vertical photography, ground surveys, and time-lapse cameras. At this frequency of observation, the terminus position is found to fluctuate seasonally. These seasonal fluctuations are compared with those of Columbia Glacier, where a longer detailed record is available. Although Columbia Glacier is now undergoing a drastic retreat, it continues to have seasonal length changes similar to those it experienced before the retreat began. The lengths of both Columbia and Hubbard Glaciers are extended in the spring, and retracted in the fall. The relatively long period of record for Columbia Glacier shows consistent seasonal variation in length and, when compared with the short period of record for Hubbard Glacier, suggests that there are consistent seasonal differences in length at Hubbard also. The lower Hubbard Glacier diverges, feeding ice into Disenchantment Bay and Russell Fiord, and advances and retreats synchronously over most of its width. The tidal current, which passes through the 250–500 m wide entrance to Russell Fiord, does not affect the seasonal advance and retreat in that area significantly.

Advance of Hubbard Glacier and 1986 Outburst of Russell Fiord, Alaska, U.S.A.

Hubbard Glacier, the largest tide-water glacier in North America, has advanced since it was first mapped in 1895 by moving a protective submarine moraine into the entrance of Russell Fiord. In May 1986, a weak surge of the Valerie tributary of Hubbard Glacier caused the glacier to block the fiord entrance, converting the body of water into a large glacier-dammed lake. This lake filled to a height of 25.5 m and stored 5.4 km3 of water before it burst out on 8 October 1986, producing a peak flow of 105 000 m3 s−1 averaged for 1 h. Hubbard Glacier is expected to continue advancing because its accumulation area ratio (AAR) is 0.95, which is unusually large. Such an advance would undoubtedly block Russell Fiord again. If this happens, it is predicted that the lake will fill to a height of 39 m over a period of 1.1–1.5 years and then overflow into the Situk River near Yakutat. This, in turn, would increase the average flow of that small stream from ils present rate of between 10 and 15 ms−1 to an estimated annual average discharge of 230 m s−1. Such an increase in flow would be expected to flood and erode forest lands, fish habitats, subsistence fishing camps, archaeological sites, and roads. At the same time, the increased water depth in Russell Fiord could be expected to increase the calving rate of Hubbard Glacier, potentially threatening the stability of its calving terminus.

Advance of Hubbard Glacier and 1986 Outburst of Russell Fiord, Alaska, U.S.A.

Hubbard Glacier, the largest tide-water glacier in North America, has advanced since it was first mapped in 1895 by moving a protective submarine moraine into the entrance of Russell Fiord. In May 1986, a weak surge of the Valerie tributary of Hubbard Glacier caused the glacier to block the fiord entrance, converting the body of water into a large glacier-dammed lake. This lake filled to a height of 25.5 m and stored 5.4 km3 of water before it burst out on 8 October 1986, producing a peak flow of 105 000 m3 s−1 averaged for 1 h.Hubbard Glacier is expected to continue advancing because its accumulation area ratio (AAR) is 0.95, which is unusually large. Such an advance would undoubtedly block Russell Fiord again. If this happens, it is predicted that the lake will fill to a height of 39 m over a period of 1.1–1.5 years and then overflow into the Situk River near Yakutat. This, in turn, would increase the average flow of that small stream from ils present rate of between 10 and 15 ms−1 to an estimated annual average discharge of 230 m s−1. Such an increase in flow would be expected to flood and erode forest lands, fish habitats, subsistence fishing camps, archaeological sites, and roads. At the same time, the increased water depth in Russell Fiord could be expected to increase the calving rate of Hubbard Glacier, potentially threatening the stability of its calving terminus.

VII.—Glaciers of the Yakutat Bay Region, Alaska

The United States Geological Survey has issued a paper, by Professor R. S. Tarr, of Cornell University, on the Physiography and Glacial Geology of the Yakutat Bay Region of Alaska. Here we have high coastal ranges, culminating in Mounts Cock and Seattle, from which descend great glaciers to the sea, and also other glaciers which come down to the waters of Russell Fiord. The whole region shows signs of intense glaciation during quite recent times, and on this account is an admirable area for the study of glaciers and their work.