Performance of Wielandt-Streckeisen STS-1 seismometers in the tidal domain—preliminary results

doi:10.1016/0031-9201(94)90039-6

Physics of the Earth and Planetary Interiors

Volume 84, Issues 1–4, July 1994, Pages 161-178

https://doi.org/10.1016/0031-9201(94)90039-6 Get rights and content

Abstract

The aim of this work is to show that STS-1 seismometers are able to provide a signal with a very long period vertical component which can be used for Earth tide studies provided a number of recording conditions are improved. We use data from the GEOSCOPE network for BNG (Bangui, Central African Republic), MBO (M'bour, Senegal), CRZF (Crozet, TAAF (Terres Australes et Antarctiques FranDc¸aises), Indian Ocean), ECH (Echery, France) and PAF (Port-aux-FranDc¸ais, Kerguelen, TAAF, Indian Ocean) stations operated by the Ecole et Observatoire de Physique du Globe de Strasbourg (EOPGS) and Institut FranDc¸ais de Recherche Scientifique pour le De´veloppement en Coope´ration (ORSTOM). These data are analysed with a least-squares adjustment method to fit the Earth tidal waves, and the results for these stations are compared. Special attention is paid to the comparison of results from ECH with those from the superconducting gravimeter of Strasbourg (J-9). For several stations used in this study (CRZF, MBO and ECH) the results are promising, but they are disappointing for others (PAF and BNG). We did not find any clear reason for such a difference in quality. We propose some improvements that will enable researchers to achieve a better recording of this long-period signal and obtain higher-quality data allowing gravimetric studies from global seismological networks.

Reference (23)

DehantV. et al.
Comparison between the theoretical and observed tidal gravimetric factors
Phys. Earth Planet. Inter.
(1987)
FlorschN. et al.
Preliminary spectral analysis of the residual signal of the superconducting gravimeter below one day period
Phys. Earth Planet. Inter.
(1991)
MelchiorP. et al.
Discussion of worldwide measurements of tidal gravity with respect to oceanic interactions, lithospheric heterogeneities
RydelekP. et al.
On tidal gravity, heat flow and lateral heterogeneities
Phys. Earth Planet. Inter.
(1991)
AgnewD.C. et al.
Vertical seismic noise at very low frequencies
J. Geophys. Res.
(1978)
BernardP. et al.
The G-calibration: a new method for an absolute in situ calibration of long-period accelerometers, tested on the Streckeisen instruments of the GEOSCOPE network
Bull. Seismol. Soc. Am.
(1991)
CumminsP. et al.
Constraining core undertones using stacked IDA gravity records
Geophys. J. Int.
(1991)
DucarmeB. et al.
Three years of registration with a superconducting gravimeter at the Royal Observatory of Belgium
HindererJ.
Recueil de 1024 poe`mes ‘Gravitons et Litrons’
(1990)
HindererJ. et al.
Elasto-gravitational deformation relative gravity changes and Earth dynamics
Geophys. J.
(1989)

HindererJ. et al.

On the calibration of a superconducting gravimeter using absolute gravity measurements

Geophys. J. Int.

(1991)

Cited by (16)

On the origin of the signals observed across the seismic spectrum
2016, Earth-Science Reviews
Citation Excerpt :
Earth tides can be used to get information of the Earth interior, as estimations of the flattening of the core-mantle boundary, or to improve the accuracy of other measurements, as the positions given by GNSS networks (Agnew, 2007). Earth tides are typically recorded using tiltmeters, strainmeters, gravimeters or space geodesy instruments (Agnew, 1986), but the displacements induced by solid Earth tides produce tilting that can also be detected by broad-band seismic sensors, in some cases with accuracy similar to supercomputing gravimeters (Pillet et al., 1994; Freybourger et al., 1997). However, using broad-band seismometers to monitor Earth tide variations is only possible in locations with favorable conditions, as these signals are often masked by the effect of temperature and pressure changes, which can deform the vault or sensor casing, modifying the instrument response or altering the mechanical properties of the material surrounding the sensor, hence producing a signal not related to the elastic deformation of the Earth (Wolin et al., 2015).
The increasing number of broad-band seismic stations recording the full spectrum of the seismic wavefield continuously has boosted interest in background signals recorded in the absence of earthquakes. Different human-made and natural phenomena other than earthquakes result in Earth vibrations that are recorded on seismometers. Those signals have classically been considered as disturbing noise, but in the last decades this view has turned, as it has been shown that seismic data can be used not only to monitor earthquake activity, but also to investigate climatic changes, track hurricanes, monitor river flows, or survey anthropogenic activity, hence making new links between seismology and different research fields. This contribution reviews state-of-the-art knowledge on the sources of seismic energy in different frequency bands using a single, two-weeks-long, seismic data file recorded by a high quality broad-band station located in the Pyrenees. This data allows exploration of the wide spectrum of ground motion, enabling a review of different processes involved in the generation of what seismologists commonly regard as background noise when focusing on ground motion from local and teleseismic earthquakes and explosions recorded in the same time interval.
Vertical and horizontal seismometric observations of tides
2006, Journal of Geodynamics
Citation Excerpt :
Gravimeters and tiltmeters are extensively used to study tides. However broadband seismometers can also be sensitive at tidal frequencies as shown by Pillet et al. (1994). These authors used POS channel (which stands for the mass position output and which is proportional to the ground acceleration at long periods) to compare STS-1 seismometers and gravimeters in the diurnal and semidiurnal bands; tides are well recovered with seismometers, however they found tidal residuals about 10 times larger compared to gravimeters.
Tidal signals have been largely studied with gravimeters, strainmeters and tiltmeters, but can also be retrieved from digital records of the output of long-period seismometers, such as STS-1, particularly if they are properly isolated. Horizontal components are often noisier than the vertical ones, due to sensitivity to tilt at long periods. Hence, horizontal components are often disturbed by local effects such as topography, geology and cavity effects, which imply a strain–tilt coupling. We use series of data (duration larger than 1 month) from several permanent broadband seismological stations to examine these disturbances. We search a minimal set of observable signals (tilts, horizontal and vertical displacements, strains, gravity) necessary to reconstruct the seismological record. Such analysis gives a set of coefficients (per component for each studied station), which are stable over years and then can be used systematically to correct data from these disturbances without needing heavy numerical computation. A special attention is devoted to ocean loading for stations close to oceans (e.g. Matsushiro station in Japon (MAJO)), and to pressure correction when barometric data are available. Interesting observations are made for vertical seismometric components; in particular, we found a pressure admittance between pressure and data 10 times larger than for gravimeters for periods larger than 1 day, while this admittance reaches the usual value of $- 3.5$ nm/s²/mbar for periods below 3 h. This observation may be due to instrumental noise, but the exact mechanism is not yet understood.
The NetLander very broad band seismometer
2000, Planetary and Space Science
The interior of Mars is today poorly known, in contrast to the Earth interior and, to a lesser extent, to the Moon interior, for which seismic data have been used for the determination of the interior structure. This is one of the strongest facts motivating the deployment on Mars of a network of very broad band seismometers, in the framework of the 2007 CNES-NASA joint mission. These seismometers will be carried by the Netlanders, a set of 4 landers developed by a European consortium, and are expected to land in mid-2008. Despite a low mass, the seismometers will have a sensitivity comparable to the present Very Broad Band Earth sensors, i.e. better than the past Apollo Lunar seismometers. They will record the full range of seismic and gravity signals, from the expected quakes induced by the thermoelastic cooling of the lithosphere, to the possible permanent excitation of the normal modes and tidal gravity perturbations. All these seismic signals will be able to constrain the structure of Mars’ mantle and its discontinuities, as well as the state and size of the Martian core, shortly after for the centennial of the discovery of the Earth core by Oldham (Quart. J. Geol. Soc. 62(1906) 456–475).
Comparative study of superconducting gravimeters and broadband seismometers STS-1/Z in seismic and subseismic frequency bands
1997, Physics of the Earth and Planetary Interiors
Superconducting gravimeters and broadband seismometers (vertical component) both measure gravity, but whereas the former are most sensitive to very long period signals (gravity tides with periods longer than 6 h), the latter are designed for recording the seismic band (elastic normal modes with periods shorter than 1 h). We investigate here the behaviour of each type of instrument in the spectral band where it is not generally used. More precisely, we compare the French superconducting gravimeter, located at Station J9 near Strasbourg, and the vertical component of an STS-1 seismometer located in a mine at Echery (ECH) in the Vosges, about 70 km away. Two different frequency bands are considered: the seismic band (frequencies between 0.2 and 1.667 mHz), for the study of normal modes after the Bolivian earthquake of 9 June 1994, and the subseismic band (frequencies lower than 0.2 mHz), including the study of gravity tides. The analysis of Fourier amplitude spectra and power spectral densities shows the obvious result that the broadband seismometer is more sensitive than the superconducting gravimeter in the seismic band because of a lower noise level, whereas the reverse is true in the subseismic band. The poorer quality of the gravimeter record in the seismic band is probably due to site effects (sediments vs. bedrock) rather than of instrumental origin. In contrast, the higher noise level of the seismometer in the subseimic band is probably due to the temperature response of the instrument. It is expected that operating the STS-1 isothermally, or recording on-site temperature changes for correction will considerably improve its signal-to-noise ratio in the subseimic band. In comparison with recent mean models of high and low seismic background noise levels, both instruments nevertheless indicate low noise levels at all frequencies.
From Chandler wobble to free oscillations: comparison of cryogenic gravimeters and other instruments in a wide period range
1995, Physics of the Earth and Planetary Interiors
The cryogenic gravimeter was developed to overcome the mechanical deficiencies of spring gravimeters. The stability of the instrument permits the study of long-term gravity variations for the first time. Short-term, especially periodical gravity variations have been well observed with spring gravimeters. This investigation tries to determine up to what level and frequency the various types of instrument have equivalent quality. Side-by-side runs of two cryogenic instruments, and comparisons with relative spring gravimeters and long-period seismometers, should help to answer this question. From the intercomparison of two cryogenic gravimeters in Bad Homburg, Germany (TT40 and TT60) and in Miami, USA (TT40 and UCSD SG B) one can see that, in general, the gravity signals coincide within several nanometres per second squared, but also intervals are noted where the differences are 10–30 nm s⁻² over a timespan of 1–3 months. Usually, known instrumental problems are the cause for these discrepancies. Data analysis as well as comparisons with absolute gravity measurements in parallel demonstrate that the drift of the meters is monotonic and in general has exponential characteristics. This allows investigations in the long-period tide band as well as in the range of long-term gravity variations, e.g. the gravitational effects of polar motion, water table and air pressure variations. At the other end of the spectrum—in the period range from 15 min to 1 day—a side-by-side run of the cryogenic gravimeter SG-102 and the spring gravimeter LCR-ET-19 in the Black Forest Observatory in Schiltach, Germany, shows that the noise spectrum of the spring gravimeter is slightly lower than that of the cryogenic one. Analysis of the free oscillations of the Earth from several large earthquakes shows that this spring gravimeter and modern seismometers are at least of equal quality. Data sets recorded with cryogenic gravimeters open the possibility of investigating gravity variations in a wide frequency range. However, especially for investigations in the high-frequency band (1 c day⁻¹ and above), one should also make use of well-maintained conventional spring gravimeters and possibly modern force-balance seismometers, which may have at least the same or better quality.
Ultra-Low-Frequency Tri-Component Fiber Optic Interferometric Accelerometer
2018, IEEE Sensors Journal

View all citing articles on Scopus

View full text

Performance of Wielandt-Streckeisen STS-1 seismometers in the tidal domain—preliminary results

Abstract

Phys. Earth Planet. Inter.

Phys. Earth Planet. Inter.

Phys. Earth Planet. Inter.

Vertical seismic noise at very low frequencies

J. Geophys. Res.

The G-calibration: a new method for an absolute in situ calibration of long-period accelerometers, tested on the Streckeisen instruments of the GEOSCOPE network

Bull. Seismol. Soc. Am.

Constraining core undertones using stacked IDA gravity records

Geophys. J. Int.

Three years of registration with a superconducting gravimeter at the Royal Observatory of Belgium

Recueil de 1024 poe`mes ‘Gravitons et Litrons’

Elasto-gravitational deformation relative gravity changes and Earth dynamics

Geophys. J.

On the calibration of a superconducting gravimeter using absolute gravity measurements

Geophys. J. Int.