Mathematics – Logic
Scientific paper
Dec 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003agufm.g21c0282h&link_type=abstract
American Geophysical Union, Fall Meeting 2003, abstract #G21C-0282
Mathematics
Logic
1200 Geodesy And Gravity, 1208 Crustal Movements: Intraplate (8110), 1244 Standards And Absolute Measurements, 1294 Instruments And Techniques, 1299 General Or Miscellaneous
Scientific paper
The Nouveau Quebec-Labrador region was the site of one of the major ice domes of the Laurentide Ice Sheet and is currently experiencing postglacial rebound. Geodetic data provide a useful and accurate method of measuring the pattern and rates of contemporary uplift in this region. In order to monitor the temporal variations in gravitational potential resulting from regional glacial isostatic adjustment, a number of absolute gravity sites have been established in northern Quebec. These absolute-gravity field stations are co-located with sites of the Canadian Base Network (CBN). Initiated in 1994, the CBN is a network of pillar monuments with forced-centering plates for Global Positioning System (GPS) receiver antennae. Accurately positioned three-dimensionally with GPS, the CBN can serve as a monitoring network for deformation studies of the Canadian landmass. Issues such as mass redistribution or changes in density contrasts within the Earth may be better addressed by monitoring positional changes (i.e., primarily height changes) and integrating these observations with gravitational variations. The comparison of the temporal rate of change of gravity with the GPS height rate is thus highly desirable. Recent velocity estimates based on both the multiple-epoch GPS network surveys as well as the preliminary results from absolute-gravity trends indicate regional uplift. These preliminary results also exhibit general agreement among the uplift rates for GPS radial velocities, gravity trends, and predictions of vertical crustal motion from postglacial rebound models.
Monitoring the temporal rate of change of gravity at key GPS sites is also an important step towards the maintenance of an integrated reference system. Co-located with the Canadian Geodetic Long Baseline Interferometry site at the Algonquin Radio Observatory (A.R.O.), the Canadian Active Control System's continuous GPS station at Algonquin Park, Ontario (ALGO) serves as an important reference site for many regional surveys, including this study. A.R.O. has thus been singled out as a key field station where a comparison of the temporal rate of change of gravity with the GPS radial position rate of change is highly desirable. Unfortunately to date, the uplift rate determined from the gravity trend at Algonquin Park appears much larger than the GPS-observed and model-predicted rates. With the gravity measurements taken at the stable base of the Algonquin Radio Observatory's 46m VLBI telescope, the cause of this apparently high uplift rate is unknown. Although the data will be further analyzed for possible instrumental offsets or biases, it is likely that the gravity trend is biased by variations in the local mass budget due to environmental or hydrological effects. To quantify these effects, we have begun more frequent ( ˜monthly) absolute gravity measurements. Additionally, pending further testing and evaluation, data from an autonomous, continuously-recording (but yet to be installed) gravimeter will be coupled with the absolute measurements to develop and test models of seasonal variations in the gravity field at A.R.O. due to groundwater effects.
Craymer M. R.
Gagnon George C.
Henton Joseph A.
Lapelle E.
Liard Jacques O.
No associations
LandOfFree
Absolute Gravity and Global Positioning System Measurements of Uplift in Quebec and Eastern Ontario, Canada does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Absolute Gravity and Global Positioning System Measurements of Uplift in Quebec and Eastern Ontario, Canada, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Absolute Gravity and Global Positioning System Measurements of Uplift in Quebec and Eastern Ontario, Canada will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1424573