title: Comparing a new laser strainmeter array with an adjacent, parallel running quartz tube strainmeter array.
abstract: In summer 2011, two new laser strainmeters about 26.6 m long were installed in N-S and E-W directions parallel to an existing quartz tube strainmeter system at the Geodynamic Observatory Moxa, Thuringia/Germany. This kind of installation is unique in the world and allows the direct comparison of measurements of horizontal length changes with different types of strainmeters for the first time. For the comparison of both data sets, we used the tidal analysis over three years, the strain signals resulting from drilling a shallow 100 m deep borehole on the ground of the observatory and long-period signals. The tidal strain amplitude factors of the laser strainmeters are found to be much closer to theoretical values (85%-105% N-S and 56%-92% E-W) than those of the quartz tube strainmeters. A first data analysis shows that the new laser strainmeters are more sensitive in the short-periodic range with an improved signal-to-noise ratio and distinctly more stable during long-term drifts of environmental parameters such as air pressure or groundwater level. We compared the signal amplitudes of both strainmeter systems at variable signal periods and found frequency-dependent amplitude differences. Confirmed by the tidal parameters, we have now a stable and high resolution laser strainmeter system that serves as calibration reference for quartz tube strainmeters.
authors.affiliation: Institute of Geosciences, Friedrich Schiller University Jena, Burgweg 11, 07749 Jena, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Kobe
authors.affiliation: Institute of Geosciences, Friedrich Schiller University Jena, Burgweg 11, 07749 Jena, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Jahr
authors.affiliation: SIOS Meßtechnik GmbH, Am Vogelherd 46, 98693 Ilmenau, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Pöschel
authors.affiliation: Institute of Geosciences, Friedrich Schiller University Jena, Burgweg 11, 07749 Jena, Germany.
authors.forename: Nina
authors.initials: N
authors.lastname: Kukowski