Seafloor Ground Rotation Observations: Potential for Improving Signal‐to‐Noise Ratio on Horizontal OBS Components

Lindner, Fabian; Wassermann, Joachim; Schmidt‐Aursch, Mechita C.; Igel, Heiner

doi:10.1785/0220160051

Cited by 23 publications

(16 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since single-station 6DOF recordings provide direct access to the phase velocity and propagation direction under the plane wave assumption (Equation (16)), they theoretically provide similar capabilities in extracting the vector velocity as seismological arrays, which is why 6DOF recording stations are sometimes referred to as 'point seismic arrays' [27]. The rich amount of information that can be extracted from 6DOF recordings makes such 'point arrays' attractive for the deployment in areas where extended receiver arrays cannot be used, for example, on the ocean bottom [28], in mountainous areas, or in extraterrestrial seismology [29].…”

Section: Array-like Capabilites Of Single-station 6dof Measurementsmentioning

confidence: 99%

“…Various authors discuss the deteriorating effects that rotations (particularly tilt) can have on the recordings of conventional inertial seismometers [91][92][93][94] and suggest potential correction schemes [9,93,[95][96][97]. Tilt contamination of inertial seismometer recordings has been shown to be significant, for example, in the near field of active volcanoes [98] and on the ocean bottom [28] and was demonstrated to have an adverse effect on moment tensor inversions [98].…”

Section: Tilt Corrections Of Translational Datamentioning

confidence: 99%

“…A major advantage of fibre-optical sensors is that they are inherently insensitive to translational motion. Fibre-optic gyroscopes were already successfully employed for seismological applications [28,[123][124][125][126][127]. Recently, the first commercial fiber optic gyroscope designed specifically for the needs of seismology has become available blueSeis-3A by iXBlue, France [12].…”

Section: Direct Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Seismological Processing of Six Degree-of-Freedom Ground-Motion Data

Sollberger

Igel

Schmelzbach

et al. 2020

Sensors

Self Cite

View full text Add to dashboard Cite

Recent progress in rotational sensor technology has made it possible to directly measure rotational ground-motion induced by seismic waves. When combined with conventional inertial seismometer recordings, the new sensors allow one to locally observe six degrees of freedom (6DOF) of ground-motion, composed of three orthogonal components of translational motion and three orthogonal components of rotational motion. The applications of such 6DOF measurements are manifold—ranging from wavefield characterization, separation, and reconstruction to the reduction of non-uniqueness in seismic inverse problems—and have the potential to revolutionize the way seismic data are acquired and processed. However, the seismological community has yet to embrace rotational ground-motion as a new observable. The aim of this paper is to give a high-level introduction into the field of 6DOF seismology using illustrative examples and to summarize recent progress made in this relatively young field. It is intended for readers with a general background in seismology. In order to illustrate the seismological value of rotational ground-motion data, we provide the first-ever 6DOF processing example of a teleseismic earthquake recorded on a multicomponent ring laser observatory and demonstrate how wave parameters (phase velocity, propagation direction, and ellipticity angle) and wave types of multiple phases can be automatically estimated using single-station 6DOF processing tools. Python codes to reproduce this processing example are provided in an accompanying Jupyter notebook.

show abstract

Section: Array-like Capabilites Of Single-station 6dof Measurementsmentioning

confidence: 99%

Section: Tilt Corrections Of Translational Datamentioning

confidence: 99%

Section: Direct Observationsmentioning

confidence: 99%

See 1 more Smart Citation

Seismological Processing of Six Degree-of-Freedom Ground-Motion Data

Sollberger

Igel

Schmelzbach

et al. 2020

Sensors

Self Cite

View full text Add to dashboard Cite

show abstract

“…More relevant for field-type seismic experiments are the recent developments providing seismology with portable broadband rotation sensor technology (e.g., Bernauer et al, 2012Bernauer et al, , 2018Brokesova et al, 2012;Jaroszewicz et al, 2012). With appropriate sensitivity there is a broad spectrum of applications ranging from tilt-corrections to improve the quality of classic seismometer records (Lindner et al, 2017;Bernauer et al, 2020), to site-effect characterization (e.g., Keil et al, 2020), seismic source inversion (e.g., Donner et al, 2016), separation of wavefields (e.g., Sollberger et al, 2018), volcano seismology (e.g., Wassermann et al, 2020), seismic exploration (e.g., Li and van der Baan, 2017), or structural engineering (e.g., Trifunac, 2009;Schreiber et al, 2009d). The current portable rotation sensing technology is not sensitive enough to measure below the physical noise level of our planet (e.g., ocean generated noise).…”

Section: Introductionmentioning

confidence: 99%

ROMY: A Multi-Component Ring Laser for Geodesy and Geophysics

Igel¹,

Schreiber²,

Gebauer³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Single-component ring lasers have provided high-resolution observations of Earth's rotation rate as well as local earthquake-or otherwise-induced rotational ground motions. Here we present the design, construction, and operational aspects of ROMY, a four-component, tetrahedral-shaped ring laser installed at the Geophysical Observatory Fürstenfeldbruck near Munich, Germany. Four equilateral, triangular-shaped ring lasers with 12 m side length provide rotational motions that can be combined to construct the complete vector of Earth's rotation from a point measurement with very high resolution. Combined with a classic broadband seismometer we obtain the most accurate 6 degree-of-freedom ground motion measurement system to date, enabling local and teleseismic observations as well as the analysis of ocean-generated Love and Rayleigh waves. The specific design and construction details are discussed as are the resulting consequences for permanent observations. We present seismic observations of local, regional, and global earthquakes as well as seasonal variations of oceangenerated rotation noise. The current resolution of polar motion is discussed and strategies how to further improve long-term stability of the multi-component ring-laser system are presented.

show abstract

“…They were primarily estimated using dense arrays (Huang 2003;Bodin et al 1997;Spudich et al 1995) for a very long time because seismic instruments to measure them were either not reliable enough or sensitive enough in the required frequency bands, thus leading (Aki & Richards 1980, p. 489) to note that seismology still awaits a suitable instrument for such measurements. Nowadays, rotations can be measured using liquid-based motion sensors (Egorov et al 2015;Huang et al 2013), magneto-hydrodynamic sensors (Pierson et al 2016), ring laser gyroscopes (Schreiber et al 2009; Correcting wavefield gradients for the effects of local small-scale heterogeneities 3 Pancha et al 2000;McLeod et al 1998), mechanical sensors (Brokešová & Málek 2013) and more recently, using fiber-optic gyroscopes (Bernauer et al 2018;Lindner et al 2016;Kurzych et al 2014). Similarly, strains can be measured using Distributed Acoustic Sensing (DAS) (Willis et al 2016) and Distributed Vibration Sensing (DVS) (Dean et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Correcting wavefield gradients for the effects of local small-scale heterogeneities

Singh

Capdeville

Igel

2019

Geophysical Journal International

Self Cite

View full text Add to dashboard Cite

Summary Local small-scale heterogeneities, like geological inhomogeneities, surface topographies and cavities are known to affect seismic wavefield gradients. This effect is in fact measurable with current instruments. For example, the agreement between data and synthetics computed in a tomographic model is often not as good for rotation as it is for displacement. Here, we use the theory of homogenization to explain why small-scale heterogeneities strongly affect wavefield gradients, but not the wavefield itself. We show that at any receiver measuring wavefield gradient, small-scale heterogeneities cause the wavefield gradient to couple with strain through a coupling tensor J. Furthermore, we show that this J is (1) independent of source, (2) independent of time, but (3) only dependent on the receiver location. Consequently, we can invert for J based on an effective model for which synthetics fit displacement data reasonably well. Once inverted, J can be used to correct rotations at that receiver for other sources. Results of the correction are shown for synthetic rotational receivers and for the ring laser located in Wettzell, Germany. We find that compared to synthetics, the synthetics corrected through J are a better fit to the rotation data. Although results here are derived for rotations, they can be extended to receivers measuring any wavefield gradient.

show abstract

Seafloor Ground Rotation Observations: Potential for Improving Signal‐to‐Noise Ratio on Horizontal OBS Components

Cited by 23 publications

References 28 publications

Seismological Processing of Six Degree-of-Freedom Ground-Motion Data

Seismological Processing of Six Degree-of-Freedom Ground-Motion Data

ROMY: A Multi-Component Ring Laser for Geodesy and Geophysics

Correcting wavefield gradients for the effects of local small-scale heterogeneities

Contact Info

Product

Resources

About