High Precision Deformation Monitoring at the Geodynamic Observatory Moxa/Thuringia, Germany

Abstract

AbstractWith strainmeters the observation of crustal deformation is possible with a resolution better than 10−9 m. At the Geodynamic Observatory Moxa in Thuringia/Germany an assembly of strainmeters of different types is recording deformation. Deformation mainly results from the tidal forces of sun and moon acting on the Earth, but also comes from seismic wave propagation or regional and local sources. Here we describe the results of an analysis of five time-series, each spanning 482 days, obtained from the different instruments and areal strain. We focus on the Earth tides but also look on the resonance of the Earth’s core to tidal forcing, the Nearly Diurnal Free Wobble. Even if not all five time-series show the resonance, its finding, especially in strain data, confirms the high data quality and sensitivity of the instruments. The analysis of the strainmeter data shows the comparability of the data from the different instruments as well as the good data quality connected to the very low noise level at the Geodynamic Observatory Moxa. Comparison with ocean loading shows that strong effects from local conditions like topography or rock inhomogeneities exist.KeywordsEarth tidesStrainmeter systemsDeformation monitoringNearly Diurnal Free Wobble