Surge of McGinnis Glacier, Alaska RangeIn March 2006 we discovered recent surge activity on the relatively small McGinnis Glacier in the Alaska Range. The glacier had advanced by more than one kilometer. It looked like the surge had already come to a stop. Check out this link for pictures, map location, and information on what little is known about the glacier.
Measuring ice deformation rates on Black Rapids GlacierIn this project we used tilt meters to measure ice deformation rates and their changes, as basal conditions change. The tilt meters are very senstive. For example, they picked up tiny signals during two earthquakes in October and November 2002 (see below). Ice deformation rates are expected to change when basal stress gets re-distributed. The image on the left shows an example of modelled stress in a cross section of the glacier. The left picture shows stress distribution if basal motion is uniform across the section. The right image shows the same cross section if the middle section is sufficiently lubricated, so that it can only support a small amount of shear stress. This stress redistribution is reflected in ice deformation rates. (or up- and downstream). The modeling was done with the commercial package FemLab .
Support: NSF OPP-0115819
Effects of the M7.9 Denali Fault earthquake on glaciersThe M7.9 Alaska earthquake on 3 November caused surface rupture on many of the glaciers along the Denali Fault. Horizontal as well as vertical displacements were observed. The most dramatic effects were the many avalanches and some huge rock falls onto the Black Rapids and Gakona Glaciers. We presented a summary of these effects at this year's AGU Fall meeting ( poster ). I also gave a talk about the effects of the earthquake on Black Rapids Glacier at a AAAS meeting in Fairbanks and at the annual Northwest Glaciology Meeting in Portland. See the slides
Check out the sites below to find out more about this spectacular event and see some pictures:
Partial Support: NSF OPP-0115819
Monitoring mass balance, speed and elevation of Black Rapids GlacierSince 1973 the mass balance, annual surface speed, and the elevation at several fixed map coordinates has been measured. This work was initiated by the US Geological Survey, Water Resources group. More recently the measurements have been done at University of Alaska Fairbanks, usually at times when other research activities were going on. Results up to 1995 were published by Heinrichs et al. in J. Glac. Click here for the updated measurements.
Support (most recently): NSF OPP-0115819
The advance of the Hubbard Glacier, Southeast AlaskaHubbard Glacier is the largest tidewater glacier in North America and one of a few that are in the advance phase of the tidewater glacier cycle. Its advance is of particular interest, because it has closed off Russell Fiord twice in the last 16 years (1986, 2002) and it will do so again. In 1986 and again in 2002, the dam created by the glacier eventually failed and created a huge flood. The community of Yakutat is concerned that a permanent closure of the fiord will cause an overflow into the Situk River drainage, which is a world class Steelhead fishery. The picture shows the glacier terminus near Gilbert Point, where the fiord closure has occurred.
Roman Motyka and I have done bathymetry in the area to monitor how the glacier fills in the fiord, and how the catastrophic flood eroded sediments. We also installed an automatic camera that takes a picture of the glacier front every day.
Find out more about Hubbard and see some nice picture of the recent close-off at
Some pictures of a calving event:
Support: NSF OPP 0221307
Deformation of proglacial sediments at Taku GlacierTaku Glacier, near Juneau, has advanced for more than a hundred years now. During its advance it filled in the fiord and eventually stopped being a calving glacier. At the moment this glacier continues to excavate subglacial sediments and deposit them into the proglacial fiord. Its advance creates push moraines and it is deforming the proglacial sediments in some unusual bulges (see picture on the right). We are measuring the advance of the glacier, and the deformation in the proglacial sediments.
Support: NSF OPP 0221307
A new method for instrument placement into subglacial tillTogether with our machine shop we designed and built a down-borehole hammer capable of inserting instruments into subglacial till. The hammer was field tested on Black Rapids Glacier in April/May 2002. We were able to penetrate over 2 m of subglacial till, under 500 m of glacier ice.
With our electronics shop we also designed and built wireless instrument probes. They measure pore pressure and tilt, and send the results to a receiver that is hanging a few meters higher in the ice part of the borehole.
We also installed tilt sensors in several boreholes to measure ice deformation. The goal of this project is to get a high time resolution record of ice deformation. Changes in the distribution of basal shear stress should lead to changes in ice deformation rates. We are trying to use the measured ice deformation rates to infer the distribution of basal shear stress.
Support: NSF OPP 0082549 and OPP 0115819
The 2000/2001 surge of Yanert Glacier, Alaska RangeYanert Glacier in the Alaska Range started a spectacular surge in 2000. The surge stopped in summer 2000 and picked up again in the following winter. This is not uncommon. In 2001 the Alaska Range saw three surges (Yanert, Lakuna, Tokositna) after a period of 6 years without any observed surges. The Yanert Glacier had last surged in 1942. Click here for some pictures of Yanert Glacier.
Support: NSF OPP 0126363
LeConte Glacier, Southeast AlaskaIn the first half of 2000 I was working on LeConte Glacier, a retreating tide water glacier. We measured its ice thickness with seismic methods and found over 1300 m of ice. The glacier is one of the fastest moving on the planet; it was ripping along at 26 m/d! I also developed some software to do photogrammetry to find the terminus position of the glacier.
Ice stream marginsMuch of the West Antarctic Ice Sheet is drained by fast flowing ice streams. These ice streams are somewhat unusual, because they are comparatively thin and not very steep, so there is little gravitational pull driving them. The only reason they can maintain such fast flow is that their bases are wet and very slippery. These ice streams are therefore mostly held back by their margins, where they meet the cold and slow-flowing ice of the ice sheet. We modeled the ice dynamics in this marginal ice (e.g. WAIS poster ), and also compared it to other kinds of ice streams, like the Jakobshavn Isbrae in Greenland. Check out an Annals of Glaciology article on that, or look at a summary of our research findings , which includes some new modeling results.
Support: NSF OPP 0086997Australian Antarctic Divison in Hobart, Tasmania. I was involved in field work on Heard Island in the Southern Indian Ocean. We surveyed one particular glacier, Brown Glacier, to determine its current geometry, ice velocity and thickness. By comparing our results with pictures from 1947 we determined that the glacier has lost more than 30% of its mass since then.
Ian Allison initiated this work. Doug Thost and Andrew Ruddell were on the island with me. In December 2003 Doug Thost, Shavawn Donoghue and I went back to the island. We resurveyed much of the glacier and found that the mass loss rate has increased. We also maintained several weather stations and measured velocities, depths, isotopes and chemestry in shallow cores, and did bathymetric surveys (see our data report).
Look here for pictures of Heard Island.
Support: NSF OPP 0335936
This work formed part of Martin Luethi's PhD thesis. I also worked with Almut Iken and Martin Funk.Versuchsanstalt fuer Wasserbau, Hydrologie und Glaziologie (VAW) at ETH Zurich. I wrote a diploma thesis about Findelengletscher. This glacier has advanced rather dramatically in the late 1970s and has retreated ever since. We compared the subglacial hydrology during its advance and retreat phase.
Almut Iken was my thesis advisor. I also worked with Martin Funk.
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