NATIONAL REPORT OF THE FEDERAL REPUBLIC OF ... - IAG Office

Introduction
German investigations on geodetic research of crustal
deformation and geodynamics include geometric and
gravimetric observation campaigns, data processing and
modelling, analysis and interpretation of results, and
theoretical studies. The report for the period 2003-2007
shall be divided into the topics
– Global tectonic deformations (including plate kinematics
and dynamics);
– Glacial-isostatic adjustment (including mantle viscosity);
– Regional (primarily vertical) deformations (in Germany,
Europe and other regions);
– Theoretical studies and viscoelastic field theory.
Global tectonic deformations
Tectonic deformations on a global scale are closely
connected with plate tectonics. The kinematics of lithospheric
plates is observed by networks of the different space
geodetic techniques (GPS, SLR, VLBI, DORIS), where
German institutions are strongly involved with fundamental
observatories co-locating various techniques (Wettzell/
Germany and Concepción/Chile operated by Bundesamt
für Kartographie und Geodäsie, BKG, and Potsdam/
Germany operated by GeoForschungsZentrum Potsdam,
GFZ) and other permanent stations, mainly GPS. Actual
plate kinematic and deformation models are frequently
computed from the global observations by Deutsches
Geodätisches Forschungsinstitut (DGFI, DREWES and
MEISEL, 2003). They include now the modelling of nearly
all major plates (except Cocos) and the larger inter-plate
deformation zones (orogenes in the Mediterranean,
Himalaya, California, Andes) and provide point velocities
with accuracies better than 1 mm/year. Plate dynamics was
studied by TRUBITSYN et al. (2006).
The deformations between the rigid plates are geodetically
measured in many regional networks, mainly by GPS
observations. They include also specific projects for
earthquake research. Since many years there have been
several German projects in the Andean subduction zone in
South America. A large area in the southern and central
Andes were investigated by KHAZARADZE and KLOTZ
(2003) studying long-term and short-term effects related
to earthquakes. BAEZ et al. (2007) presented results from
the permanent Chilean network. Post-seismic mechanisms
Crustal deformation and Geodynamics
H. DREWES 1 , D. WOLF 2
1 Hermann Drewes: Deutsches Geodätisches Forschungsinstitut (DGFI), Alfons-Goppel-Str. 11, D - 80539 München, Germany,
Tel. +49 - 89 - 23031-1106, Fax +49 - 89 - 23031 1240, e-mail drewes@dgfi.badw.de
2 Detlef Wolf, GeoForschungsZentrum Potsdam (FZ), Dept. 1, Telegrafenberg, D - 14473 Potsdam, Germany, Tel. +49 - 331 - 288-1140,
Fax +49 - 331 - 288-1163, e-mail dasca@gfz-potsdam.de
79
of the 2001 Peru earthquake were investigated by HERGERT
and HEIDBACH (2006). The Cariaco earthquake in
Venezuela was studied by BAUMBACH et al. (2003). In
Europe projects concentrate on the Mid-Atlantic ridge. In
a cooperation with the Icelandic Meteorological Office and
the Nordic Volcanological Center of the Institute of Earth
Sciences (Reykjavik), the Bayerische Kommission für die
Internationale Erdmessung (BEK) participated in the
processing of GPS data from the ISGPS network in Iceland
(GEIRSSON et al., 2006). The strongest signal observed is
due to plate spreading across Iceland. The plate boundary
deformation field was affected in South Iceland by two Mw = 6.5 earthquakes in June 2000, inflation at Kafla volcano
during 2000 and 2004, and an eruption of Hekla volcano
in February 2000. KANIUTH (2005) studied the displacements
after the strong Sumatra 2004 and 2005 earthquakes.
A project for observing continental deformation in the Alps
was funded by the EU INTERREG III-B Programme.
Several research and environmental institutions from
France, Germany, Italy and Slovenia were involved. DGFI
and BEK were partners in this project. During the last three
years more than 30 permanent GPS stations were installed
in the alpine region.
General studies of mechanisms and geodetically observable
effects (gravity and position changes) were published for
convergent zones (Central America, KRAWINKEL 2003) and
spreading zones (JACOBY and CAVSAK, 2005).
Glacial-isostatic adjustment
Geographically, most studies of glacial-isostatic adjustment
(GIA) and its relation to mantle viscosity were concerned
with Fennoscandia. As a measure of GIA, present-day
temporal variations of gravity may be used. Using observations
since 1966 along a profile crossing Fennoscandia near
63º N, MÄKINEN et al. (2004, 2005) derived ratios between
gravity change and uplift of -0.16 to -0.20 :gal/mm for this
region. Recently, the relative measurements have been
complemented and will eventually be replaced by new
techniques. Thus, absolute gravity measurements have been
intensified in Fennoscandia since 2003. Simultaneously,
monthly solutions for the geoid derived from measurements
of the GRACE satellite mission have become available and
can be exploited to better constrain GIA in Fennoscandia
and elsewhere. Further details about these new initiatives
may be found in MÜLLER et al. (2003, 2005, 2006), and