HR: 1330h
AN: G42A-0043 [PDF]
TI: Monitoring anthropogenic subsidence using an absolute gravimeter in Jlich (Germany)
AU: * Van Camp, M
EM: mvc@oma.be
AF: Royal Observatory of Belgium, Avenue Circulaire, 3, Brussels, B-1180
Belgium
AB:
Since October 2000, absolute gravity (AG) measurements have been performed twice a year at the J\"{u}lich Research Centre,
Germany. This station is located in an industrialised area, closed by two opencast brown coal mines located at 4 km from the
Research Centre. To prevent the mines from being flooded, continuous water pumping has been carried out for 50 years, causing
a subsidence of more than 1 cm/yr. This presentation shows the possibility to carry out satisfactory AG measurements in a
noisy environment, able to evidence the subsidence. Today, we observe a trend of +3.7$\pm$1.3 $\mu$Gal/year, which can be
interpreted as a subsidence of -1.8$\pm$0.7 cm/yr, comparable to the repeated levellings and GPS measurements. Assuming that
the seasonal effects are the same each year, other things being equals, we should be able to confirm this gravity rate of
change at the 95% confidence level at the beginning of 2004, and at the 99% level one year later. The AG Jlich
observations are a long-term project and will get an insight into mass redistribution phenomena related to gradual surface
subsidence.
DE: 1200 GEODESY AND GRAVITY
DE: 1204 Control surveys
DE: 1208 Crustal movements--intraplate (8110)
DE: 1244 Standards and absolute measurements
DE: 1803 Anthropogenic effects
SC: Geodesy [G]
MN: 2003 Fall Meeting