scholarly journals Regional heterogeneities of the earth tides in Central Japan as revealed by tidal gravity observations.

1984 ◽  
Vol 32 (6) ◽  
pp. 485-510
Author(s):  
Takeshi ENDO
Keyword(s):  
Earth Tides ◽  
Central Japan ◽  
Tidal Gravity ◽  
The Earth ◽  
Tidal Gravity Observations

Fundamental statistical techniques for the analysis of earth tides

1971 ◽  
Vol 61 (1) ◽  
pp. 203-215
Author(s):  
Cheh Pan
Keyword(s):  
Computer Technology ◽  
Earth Tide ◽  
Power Spectra ◽  
Correlation Coefficients ◽  
Earth Tides ◽  
Statistical Techniques ◽  
The Earth ◽  
Tidal Data ◽  
Instrumental Drift ◽  
Phase Differences

abstract Recent advances in instrumentation, digital computer technology and mathematical theory promote the error analysis of Earth-tide data. Various statistical techniques developed and used in other fields are applicable in the study of Earth tides, and the accuracy of the Earth's rigidity constants determined from the tides will be greatly improved with the help of these techniques. The fundamentals of the statistical techniques of autocorrelation, crosscorrelation, convolution, statistical means, bandpass filtering, correlation coefficients, power spectra, coherency and equalization are described, and their principal applications in the Earth-tide analysis summarized. Examples of effective application of these techniques in the elimination of the errors in the tidal data such as those introduced from instrumental drift, phase differences between the observed and predicted tides, etc. are discussed. This work is an attempt to introduce statistical analysis into the Earth-tide study.

scholarly journals On Investigations of the Tidal Waves Mf and Mm

1979 ◽  
Vol 82 ◽  
pp. 315-316
Author(s):  
G. P. Pil'nik
Keyword(s):  
Solid Earth ◽  
Elastic Properties ◽  
Earth Tides ◽  
Love Number ◽  
Astronomical Observations ◽  
Tidal Waves ◽  
The Earth ◽  
Astronomical Time ◽  
Solid Earth Tides

The comparison of astronomical time observations with the theory of solid-Earth tides makes it possible to determine the Love number, k, which characterizes the elastic properties of the Earth. In addition, the comparison of values of k determined from different tidal waves allows us to judge the accuracy of the nutational theory in astronomical observations since both tides and the Earth's nutation are produced by the same causes.

scholarly journals On the link between Earth tides and volcanic degassing

2019 ◽  
Author(s):  
Florian Dinger ◽  
Stefan Bredemeyer ◽  
Santiago Arellano ◽  
Nicole Bobrowski ◽  
Ulrich Platt ◽  
...  
Keyword(s):  
Quantitative Model ◽  
Earth Tides ◽  
Bubble Coalescence ◽  
Magmatic System ◽  
Volcanic Emissions ◽  
Volcanic Gas ◽  
Tidal Variation ◽  
Magma Flow ◽  
Volcanic Degassing ◽  
The Earth

Abstract. Long-term measurements of volcanic gas emissions conducted during the recent decade suggest that under certain conditions the magnitude or chemical composition of volcanic emissions exhibits periodic variations with a period of about two weeks. A possible cause of such a periodicity can be attributed to the Earth tidal potential. The phenomenology of such a link has been debated for long, but no quantitative model has yet been proposed. The aim of this paper is to elucidate whether a causal link from the tidal forcing to variation in the volcanic degassing can be traced analytically. We model the response of a simplified magmatic system to the local tidal gravity variations and derive a periodical vertical magma displacement in the conduit with an amplitude of 0.1–1 m, depending on geometry and physical state of the magmatic system. We find that while the tide-induced vertical magma displacement has presumably no significant direct effect on the volatile solubility, the differential magma flow across the radial conduit profile may result in a significant increase of the bubble coalescence rate in a depth of several kilometres by up to several ten percent. Because bubble coalescence facilitates separation of gas from magma and thus enhances volatile degassing, we argue that the derived tidal variation may propagate to a manifestation of varying volcanic degassing behaviour. The presented model provides a first basic framework which establishes an analytical understanding of the link between the Earth tides and volcanic degassing.

A Pump-Probe Analysis of Nonlinear Elastic Behavior on the San Andreas Fault

2020 ◽  
Author(s):  
Andrew Delorey
Keyword(s):  
San Andreas Fault ◽  
Earth Tides ◽  
Elastic Behavior ◽  
Fracture Networks ◽  
Pump Probe ◽  
San Andreas ◽  
The Earth ◽  
Probe Analysis ◽  
Highly Nonlinear ◽  
Nonlinear Elastic

<p>Fracture networks in the subsurface influence nearly every aspect of earthquakes and natural hazards.  These aspects, including stress, permeability and material failure, and are important for hazard assessment. However, our ability to monitor fracture behavior in the Earth is insufficient for any type of decision-making regarding hazard avoidance.  I propose a new method for probing the evolution of fracture networks in situ to inform public safety decisions and understand natural systems. </p><p>In heterogeneous, fractured materials, like those found in the Earth, the relationship between stress and strain is highly nonlinear.  This nonlinearity in the upper crust is almost entirely due to fractures.  By measuring to what extent Earth materials exhibit nonlinear elastic behavior, we can learn more information about them.  Directly, measuring physical properties may be more useful than just detecting that fractures are present or how they are shaped and oriented.  We measure nonlinearity by measuring the apparent modulus at different strains. </p><p>In this study we use a pump-probe analysis, which involves continuously probing velocity (as a proxy for modulus) while systematically straining the material.  We will use solid Earth tides as a strain pump and empirical Green’s functions (EGF) as a velocity probe.  We apply this analysis to the San Andreas Fault near Parkfield, California.  We chose Parkfield because there is a long-term deployment of borehole seismic instruments that recorded before and after a M6 earthquake.  We find evidence that nonlinear behavior is correlated with the seismic cycle and therefore it may contain information on the both the evolution and current state of stress on faults. </p>

TIDAL GRAVITY OBSERVATIONS

Geophysics ◽  
1941 ◽  
Vol 6 (1) ◽  
pp. 81-83
Author(s):  
A. Wolf
Keyword(s):  
Gravity Variation ◽  
Tidal Gravity ◽  
Gravity Variations ◽  
Tidal Gravity Observations

Last August I sent you the manuscript of a paper on tidal gravity variations. Since that time, we made another test run of the gravimeter with very similar results. I am sending you a chart of the curves of gravity variation which we obtained.

Polar motion and earth tides from laser tracking

1977 ◽  
Vol 284 (1326) ◽  
pp. 485-494 ◽  
Keyword(s):  
Earth Tides ◽  
Length Of Day ◽  
Laser Tracking ◽  
The Earth ◽  
New Information ◽  
Single Station ◽  
Laser Systems ◽  
Rotation Of The Earth ◽  
Better Than

The tracking of near-Earth satellites with laser systems permits the determination of the variation of latitude of the tracking station and the variation in the rotation of the Earth. The present-day capability of a single station is approximately 75 cm in latitude averaged over 6h and 0.8 ms in the length of day. When the Laser Geodynamics Satellite (Lageos) is launched, a network of laser stations is projected to be able to achieve better than 10 cm in each coordinate from less than one day of tracking. The perturba­tions of near-Earth satellites by solid Earth and ocean tides are now measurable and can provide new information about the Earth and oceans. The orbit perturbations have long periods (days, months) and the analysis of orbital changes are providing estimates of the amplitudes and phases of the major tidal components.

scholarly journals Microelectromechanical system gravimeters as a new tool for gravity imaging

2018 ◽  
Vol 376 (2120) ◽  
pp. 20170291 ◽  
Author(s):  
Richard P. Middlemiss ◽  
Steven G. Bramsiepe ◽  
Rebecca Douglas ◽  
Stefan Hild ◽  
James Hough ◽  
...  
Keyword(s):  
Field Measurements ◽  
Earth Tides ◽  
Integration Time ◽  
Gravitational Acceleration ◽  
Portable Instrument ◽  
Microelectromechanical System ◽  
Tidal Forces ◽  
The Earth ◽  
Free Air ◽  
Package Size

A microelectromechanical system (MEMS) gravimeter has been manufactured with a sensitivity of 40 ppb in an integration time of 1 s. This sensor has been used to measure the Earth tides: the elastic deformation of the globe due to tidal forces. No such measurement has been demonstrated before now with a MEMS gravimeter. Since this measurement, the gravimeter has been miniaturized and tested in the field. Measurements of the free-air and Bouguer effects have been demonstrated by monitoring the change in gravitational acceleration measured while going up and down a lift shaft of 20.7 m, and up and down a local hill of 275 m. These tests demonstrate that the device has the potential to be a useful field-portable instrument. The development of an even smaller device is underway, with a total package size similar to that of a smartphone. This article is part of a discussion meeting issue ‘The promises of gravitational-wave astronomy’.

scholarly journals On the link between Earth tides and volcanic degassing

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 725-740 ◽  
Author(s):  
Florian Dinger ◽  
Stefan Bredemeyer ◽  
Santiago Arellano ◽  
Nicole Bobrowski ◽  
Ulrich Platt ◽  
...  
Keyword(s):  
Quantitative Model ◽  
Earth Tides ◽  
Bubble Coalescence ◽  
Magmatic System ◽  
Volcanic Emissions ◽  
Volcanic Gas ◽  
Tidal Variation ◽  
Magma Flow ◽  
Volcanic Degassing ◽  
The Earth

Abstract. Long-term measurements of volcanic gas emissions conducted during the last decade suggest that under certain conditions the magnitude or chemical composition of volcanic emissions exhibits periodic variations with a period of about 2 weeks. A possible cause of such a periodicity can be attributed to the Earth tidal potential. The phenomenology of such a link has been debated for long, but no quantitative model has yet been proposed. The aim of this paper is to elucidate whether a causal link between tidal forcing and variations in volcanic degassing can be traced analytically. We model the response of a simplified magmatic system to the local tidal gravity variations and derive a periodical vertical magma displacement in the conduit with an amplitude of 0.1–1 m, depending on the geometry and physical state of the magmatic system. We find that while the tide-induced vertical magma displacement presumably has no significant direct effect on the volatile solubility, the differential magma flow across the radial conduit profile may result in a significant increase in the bubble coalescence rate at a depth of several kilometres by up to several multiples of 10 %. Because bubble coalescence facilitates separation of gas from magma and thus enhances volatile degassing, we argue that the derived tidal variation may propagate to a manifestation of varying volcanic degassing behaviour. The presented model provides a first basic framework which establishes an analytical understanding of the link between the Earth tides and volcanic degassing.

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