Absolute Gravimetry in Fennoscandia: A Contribution to Understanding Postglacial Uplift

B. R Pettersen, L. TImmen, O. Gitlein, J. Muller, H. Denker, J. Makinen, M. Bilker, D.I. Lysaker, O.C. Omang, J.G. Svendsen, H. Wilmes, R. Falk, A. Reinhold, W. Hoppe, H. Scherneck, M. Lidberg, B. Engen, O. Kristiansen, A. Engfeldt, Gabriel StrykowskiRené Forsberg, F. Klopping, G. Sasagawa

Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review

Abstract

The Fennoscandian postglacial uplift has been mapped geometrically using precise levelling, tide gauges, and networks of permanent GPS stations. The results identify major uplift rates at sites located around the northern part of the Gulf of Bothnia. The vertical motions decay in all directions away from this central location. An oval shaped zero uplift isoline tracks the general western and northern coastline of Norway and the Kola peninsula. It returns southwest through Russian Karelia and touches the southern tip of Sweden and northern Denmark. The uplift area (as measured by present day motions) has its major axis in the direction of southwest to northeast and covers a distance of about 2000 km. Absolute gravimetry was made in Finland and Norway in 1976 with a rise-and fall instrument. A decade later the number of gravity stations was expanded by JILAg-5, in Finland from 1988, in Norway from 1991, and in Sweden from 1992. FG5 was introduced in these three countries in 1993 (7 stations) and continued with an extended campaign in 1995 (12 stations). In 2003 a project was initiated by IfE, Hannover to collect observations simultaneously with GRACE on an annual cycle. New instruments were acquired by IfE (FG5-220), FGI (FG5-221), and UMB (FG5-226). New absolute gravity stations were established by the national mapping agencies in Denmark, Norway, and Sweden. The total number of prepared sites in Fennoscandia is now about 30. Most of them are co-located with permanent GPS, for many of which time series of several years are now available. Along the coast there are nearby tide gauge stations, many of which have time series of several decades. We describe the observing network, procedures, auxiliary observations, and discuss results obtained for selected sites. We compare the gravity results from different instruments and discuss the challenges of combining and validating such data products. Examples are shown where temporal gravity change may be compared to geometrical movements. Various effects, both instrumental and environmental, are affecting the observed results. Some require better understanding and improved modelling. We outline the future expectations of the Fennoscandian absolute gravity project, also in relation to preliminary results from GRACE.
Original languageEnglish
Publication date2005
Publication statusPublished - 2005
EventAmerican Geophysical Union Fall Meeting 2005 - San Francisco, CA, United States
Duration: 5 Dec 20059 Dec 2005
http://www.agu.org/meetings/fm05/

Conference

ConferenceAmerican Geophysical Union Fall Meeting 2005
CountryUnited States
CitySan Francisco, CA
Period05/12/200509/12/2005
Internet address

Cite this

Pettersen, B. R., TImmen, L., Gitlein, O., Muller, J., Denker, H., Makinen, J., Bilker, M., Lysaker, D. I., Omang, O. C., Svendsen, J. G., Wilmes, H., Falk, R., Reinhold, A., Hoppe, W., Scherneck, H., Lidberg, M., Engen, B., Kristiansen, O., Engfeldt, A., ... Sasagawa, G. (2005). Absolute Gravimetry in Fennoscandia: A Contribution to Understanding Postglacial Uplift. Abstract from American Geophysical Union Fall Meeting 2005, San Francisco, CA, United States. http://adsabs.harvard.edu/abs/2005AGUFM.G24A..05P