High quality data from LaCoste-Romberg Gravimeters with Electrostatic Feedback: A challenge for superconducting Gravimeters. W. Zürn, H.-G. Wenzel and G. Laske, 1991, Bull. Inform. Marrees Terrestres, Vol. 110, p. 7942 - 7952
From Chandler wobble to free oscillations: comparison of cryogenic gravimeters and other instruments in a wide period range. Richter, B. and Wenzel, H.-G. and Zürn, W. and Klopping, F., 1995, Phys. Earth Planet. Int., Vol. 91, 131-148.
On noise reduction in vertical seismic records below 2 mHz using local barometric pressure (W. Zürn and R. Widmer, Geophys. Res. Lett. p. 3537-3540, Vol. 22, 1995)
What can superconducting gravimeters contribute to normal mode seismology? R. Widmer-Schnidrig, Bull. Seismol. Soc. Am. Vol. 93, p. 1370-1380, 2003
Nearly diurnal free wobble an tides:
Stacking gravity tide observations in central Europe for the retrieval of the complex eigenfrequency of the nearly diurnal free-wobble. J. Neuberg, J. Hinderer und W. Zürn, 1987, Geophys. J. Roy. Astr. Soc. Vol. 91, 853-868.
Observation of low order toroidal modes from the 1989 Macquarie rise event (R. Widmer, W. Zürn and G. Masters, Geophys. J. Int. p. 226-236, Vol. 111, 1992)
Observation of Coriolis coupled modes below 1 mHz. W. Zürn, G. Laske, R. Widmer-Schnidrig and F. Gilbert, 2000, Geophys. J. Int. Vol. 143, p. 113-118
Frequency dependent polarisation measurements of long-period surface waves and their implications for global phase-velocity maps. G. Laske, G. Masters and W. Zürn, 1994, Phys. Earth and Planet. Interiors.
Surface wave dispersion and upper mantle structure beneath southern Germany from joint inversion of network recorded teleseismic events. S. Stange and W. Friederich, 1993, Geophys. Res. Lett. Vol. 20, p. 2375-2378.
Shear-wave splitting in the mantle below BFO:
Shear wave splitting in the records of the German Regional Seismic Network L. P. Vinnik, V. G. Krishna, R. Kind, P. Bormann and K. Stammler. 1994, Geophys. Res. Lett. Vol. 21, No. 6, p. 457 - 460
Receiver function for BFO:
Receiver functions at the stations of the German Regional Seismic Network (GRSN) R. Kind, G. L. Kosarev and N. V. Petersen, 1995, Geophys. J. Int. Vol. 121, No. 1, p. 191 - 202
Passage of cold fronts:
Observation of Gravity changes during the Passage of cold fronts T. Müller and W. Zürn 1983, J. Geophysics, Vol. 53, p. 155-162
Bichromatic excitation of long-period Rayleigh and air waves by the mount Pinatubo and El Chichon volcanic eruptions R. Widmer and W. Zürn, 1992, Geophysical Research Letters, Vol. 19, P. 765-768
Absolute g at BFO:
In march of 2001 our colleagues from EOST Strasbourg visited BFO for the first time with their FG5 absolute gravimeter. The meter was setup in the Heinrich Kluft (outside the pressure gate) in a 2m tall, heated (~18C) styrofoam box. During one week the sensor measured g for 10 minute long intervals around the full and the half hour. The FG5 is a free-fall absolute gravimeter in which the position of a freely falling corner cube is interferometrically measured over a distance of ~25 cm. The time between successive drops was 10s. As preliminary result we show here a screen dump of the measurements. A theoretical tidal model suitable for BFO has already been subtracted from the raw measurements.
Background free oscillations observed in STS-2 data at BFO:
The background free oscillations (also known as hum) were originally detected in recordings of STS-1 seismometers of the GSN and in recordings of both spring gravimeters by LaCoste-Romberg and superconducting gravimeters by GWR. (e.g. Suda et al., SCIENCE, Vol. 279, p. 2089-2091, 1998) To our surprise we found that these modes with an rms amplitude of only 1 ngal are also present in the recordings of 7 out of 14 STS-2 seismometers of the German Regional Seismic Network (GRSN). We show here a sonogram covering two years of data from the STS-2 at BFO.