Award Abstract # 1304346
Geophysical constraints on the crust and upper-mantle structure of Greenland

NSF Org: OPP
Office of Polar Programs (OPP)
Recipient: THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK
Initial Amendment Date: May 3, 2013
Latest Amendment Date: May 3, 2013
Award Number: 1304346
Award Instrument: Standard Grant
Program Manager: Cynthia Suchman
csuchman@nsf.gov
 (703)292-2092
OPP
 Office of Polar Programs (OPP)
GEO
 Directorate for Geosciences
Start Date: September 1, 2013
End Date: August 31, 2019 (Estimated)
Total Intended Award Amount: $545,360.00
Total Awarded Amount to Date: $545,360.00
Funds Obligated to Date: FY 2013 = $545,360.00
History of Investigator:
  • Meredith Nettles (Principal Investigator)
    nettles@ldeo.columbia.edu
Recipient Sponsored Research Office: Columbia University
615 W 131ST ST
NEW YORK
NY  US  10027-7922
(212)854-6851
Sponsor Congressional District: 13
Primary Place of Performance: Columbia University Lamont-Doherty Earth Observatory
61 Route 9W
Palisades
NY  US  10964-1707
Primary Place of Performance
Congressional District:
17
Unique Entity Identifier (UEI): F4N1QNPB95M4
Parent UEI:
NSF Program(s): ANS-Arctic Natural Sciences
Primary Program Source: 0100XXXXDB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 1079
Program Element Code(s): 528000
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.078

ABSTRACT

This proposal requests support for an integrated geophysical study of the crust and upper mantle of Greenland. The study aims to characterize the seismic velocity structure of Greenland's crust and upper mantle in three dimensions; and to integrate these results with gravity and heat-flow data, laboratory estimates of material properties, and petrological data to map variations in temperature, composition, and heat flux. The project would make use of seismic data from the NSF- and internationally funded GLISN seismic network, supplemented by targeted collection of data at a limited number of temporary PASSCAL stations. The proposed research will lead to a greatly improved understanding of the crust and mantle structure of Greenland, the way this structure has evolved with time, and its influence on modern-day geophysical processes in the cryosphere and solid Earth. The results of this study will provide important inputs for ice-sheet models and models of glacial isostatic adjustment. The accuracy of both types of models is critical for accurate predictions of sea-level rise. The findings of this study will be relevant for understanding continental assembly and preservation worldwide. The seismological models derived in this project will also allow improved estimates of source parameters for tectonic and glacial earthquakes. Raw data and derived data products will be publicly available through the IRIS and UNAVCO archives. The educational materials produced through this project will be available for general use, and project outreach efforts will support U.S.-Greenland partnership in education. The project will train one graduate student and 2 to 3 undergraduate students.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

The way in which the surface of the Earth responds to changes in hydrological loads, such as ice, depends on the strength of the Earth's crust and mantle, which is not constant, but varies laterally and with depth. Similarly, the behavior of the ice sheets depends on the character of the solid Earth beneath them, including, particularly, on the heat flux from the mantle and crust. Because the propagation speed of seismic waves depends on the strength and temperature of the crust and mantle, mapping seismic wave speeds in these regions provides important knowledge for understanding changes in the ice sheets and the Earth's response to those changes. The goal of this study was to map the seismic velocity structure of the crust and mantle beneath Greenland and surrounding areas, in two and three dimensions, to provide improved constraints for interpretation of rock strength and temperature variations within the solid Earth. The study made use of seismic data from long-term observatories in and around Greenland, especially from the "GLISN" seismic network; and collected a new, two-year-long set of three-component, broadband seismic data from stations temporarily installed on the Greenland Ice Sheet and on the southeast coast of Greenland. All of the data were subjected to thorough quality-control procedures, and are now freely and openly available for further use. The seismic-velocity maps resulting from this project improve constraints on the extent of slow-velocity regions in northeast Greenland that are likely due to paleo-sediments of substantial thickness; indicate a slow-velocity corridor across central Greenland; and provide improved constraints on the structure of the seafloor separating Greenland and Iceland, and separating Greenland and Canada. Estimates of radial anisotropy (the difference in wave speed for vertically and horizontally polarized waves) were included when mapping three-dimensional structure, to allow better separation of the signals due to thermal and chemical heterogeneity in the upper mantle.


Last Modified: 12/17/2019
Modified by: Meredith Nettles

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