Expressions of Intent for International Polar Year 2007-2008 Activities

Expression of Interest Details

PROPOSAL INFORMATION

A STUDY OF GLACIER-BED SEISMICITY AND ITS SOURCE MECHANISMS AT THE SVARTISEN SUBGLACIAL LABORATORY, NORTHERN NORWAY  (GLACIER SEISMICITY)

Outline
The most dynamic behaviour of ice sheets is usually related to temporal and spatial variability of glacier sliding. Micro-seismicity measured on ice masses in polar regions contains information about glacier sliding over large distances, including slip velocity and displacement, slip areas, and basal shear stresses. However, extracting this information from seismicity is highly uncertain, due to a lack of direct measurements at glacier beds that can be used to guide seismological inversions. Without such guidance, seismological methods pioneered to characterize slip along crustal faults will continue to be underutilized for revealing characteristics of glacier sliding in polar regions. We propose an international effort to directly measure basal slip dynamics at the Svartisen Subglacial Laboratory in Arctic Norway and compare those measurements with associated micro-seismicity. This is the only facility in the world where tunnels in subglacial rock provide access to the bed of a sliding glacier greater than 200 m thick. Previous work there has indicated that the bed should be especially prone to micro-seismicity and has demonstrated important experimental capabilities: basal motion and water pressure can be measured continuously at multiple locations, shear and normal tractions on the bed can be measured locally, and basal water pressure can be increased during pump tests that perturb 10-50 m2 of the bed. Scientists from the US, UK, and Norway will bring diverse but complementary expertise to the project. The goal of the work will be to improve seismic inversion methods on glaciers by measuring, for the first time, both the characteristics of basal slip directly and measuring the seismic expression of that slip on the glacier surface and in rock tunnels beneath the glacier. In late winter, pump tests will be conducted that will bring the basal water pressure locally to the ice-overburden pressure, inducing slip over tens of square meters. Resultant seismicity will be measured at multiple locations, both at the glacier surface and below the glacier. Hypocenter location, slip kinematics, and basal shear stresses inferred from surface seismicity will be compared with direct subglacial measurements and with seismic data gathered subglacially to test and calibrate methods of seismological inversion. Results will optimize the use of micro-seismicity for studying the dynamics of glaciers in both the Arctic and Antarctic. As with previous work at the Svartisen Subglacial Laboratory, the project will also provide a platform for education and outreach.

What significant advance(s) in relation to the IPY themes and targets can be anticipated from this project?
This work will address an important unknown at a frontier of glaciology in polar regions: the extent to which glacier seismicity can be used to infer the basal dynamics of glaciers. Microseismicity will be evaluated as a tool for remotely characterizing glacier flow, and thus this study will provide a foundation for using this tool to infer temporal and spatial variability of ice-sheet dynamics. The project will be relevant to both polar regions, strengthen international collaboration, educate students, provide a mechanism for outreach, and optimize exploitation of the only polar subglacial observatory in the world.

What international collaboration is involved in this project?
Neal Iverson and Denis Cohen (US-subglacial processes) and Sridhar Anandakrishnan (US-glacier seisomology) will collaborate with Miriam Jackson (Norway-glaciologist in charge of the Svartisen Subglacial Laboratory), Gaute Lappegard (Norway-subglacial hydrology), Jemma Wadham (UK-subglacial instrumentation).

FIELD ACTIVITY DETAILS

Geographical location(s) for the proposed field activities:
The site of the of the project will be at the head of Engabreen, a temperature outlet glacier of the Svartsen Ice Cap in northern Norway (14°E, 67°N). Work will be conducted both beneath the glacier in the Svartisen Subglacial Laboratory and on the glacier surface.

Approximate timeframe(s) for proposed field activities:
Arctic: 3/2007– 5/2007      3/2008 – 5/2008      
Antarctic: n/a

Significant facilities will be required for this project:
Accommodation and equipment (e.g. hot-water drill) at the Svartisen Subglacial Laboratory. 12 seismometers (Mark Products L4-series with RefTek recorders) furnished by the PASSCAL Instrument Center, a facility supported by the US National Science Foundation that provides equipment for NSF-supported seismological studies. Both of these resources could be shared.

Will the project leave a legacy of infrastructure?
The project will improve the research infrastructure at the Svartisen Subglacial Laboratory. Capabilities will be expanded for direct measurements of sliding velocity, basal shear stress, and basal water pressure and for pressurizing the bed with water, a powerful means of both inducing seismicity and studying other aspects of basal sliding.

How is it envisaged that the required logistic support will be secured?
National agency
Commercial operator

Further details. Logistical support will come from the Norwegian Water Resources and Energy Directorate, which oversees the Svartisen Subglacial Laboratory, and from commercial sources. The most crucial of these will be the local helicopter service.

Has the project been "endorsed" at a national or international level?
The project has been endorsed by the Norwegian Water Resources and Energy Directorate, who will be providing some logistical support. Primary funding will be sought from the US National Science Foundation, which has not “endorsed” the project but has been apprised of our forthcoming proposal.

PROJECT MANAGEMENT AND STRUCTURE

Is the project a short-term expansion (over the IPY 2007-2008 timeframe) of an existing plan, programme or initiative or is it a new autonomous proposal?
Yes

The project is not part of existing plan, programme or initiative but would build on previous work on subglacial processes at the Svartisen Subglacial Laboratory.

How will the project be organised and managed?
Neal Iverson and Sridhar Anandakrishnan will co-lead the project and co-advise an existing graduate student, Peter Moore, whose dissertation the work will comprise. Iverson, Cohen and Moore will be responsible for the direct subglacial measurements. Anandakrishnan and Moore will be responsible for measuring seismicity. Miriam Jackson will manage the logistics of using the Svartisen Subglacial Laboratory, help keep the equipment there operational, and organize external logistical support. Gaute Lappegard will direct the pump tests, and Jemma Wadham will provide data gathered in a separate project aimed at developing and testing new subglacial instrumentation.

What are the initial plans of the project for addressing the education, outreach and communication issues outlined in the Framework document?
A polar scientist, Peter Moore, who did outstanding masters-level research, will receive training and support for his Ph.D. Two undergraduate field assistants will be introduced to polar research. Public fascination with the subglacial laboratory setting will be used to leverage outreach through popular-media and web-site publicity, as in past work at Svartisen.

What are the initial plans of the project to address data management issues (as outlined in the Framework document?
Data will be assembled, documented, and made available to the community using existing infrastructure mandated for use by projects funded by the US National Science Foundation-Office of Polar Programs and supported by the PASSCAL Instrument Center: the Arctic System Science Data Coordination Center and the IRIS Data Management Center, respectively.

How is it proposed to fund the project?
Funds for the project will be sought with a proposal submitted to US National Science Foundation-Office of Polar Programs. The proposal will be in response to a special IPY solicitation by that agency, which is expected in August. The submission deadline is expected to be in November, 2005.

Is there additional information you wish to provide?
We emphasize that the goal of the work will be to use the unique subglacial accesss provided by the Svartisen Laboratory to optimize seismic inversion methods for inferring sliding dynamics. Knowledge acquired will not be unique to the Svartisen Ice Cap, to either hard- or soft-bedded glaciers or to a particular geographic setting. Results will thus be applicable to ice masses at both poles.

PROPOSER DETAILS

Professor Neal Iverson
Iowa State University
253 Science I Hall
Ames, Iowa
50011
USA

Tel: 515 294 8048
Mobile: no
Fax: 515 294 6049
Email:

Other project members and their affiliation