scholarly journals Diurnal and Semidiurnal Cyclicity of Radon (222Rn) in Groundwater, Giardino Spring, Central Apennines, Italy

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1276 ◽  
Author(s):  
Marino Barberio ◽  
Francesca Gori ◽  
Maurizio Barbieri ◽  
Andrea Billi ◽  
Roberto Devoti ◽  
...  
Keyword(s):  
Earth Tides ◽  
Solar Cycles ◽  
Groundwater Levels ◽  
Natural Processes ◽  
Tidal Forces ◽  
Solid Earth Tides ◽  
Fourier Spectra ◽  
Natural Variations ◽  
Open Question ◽  
Rock Deformations

Understanding natural variations of Rn (222Rn) concentrations is the fundamental prerequisite of using this radioactive gas as a tracer, or even precursor, of natural processes, including earthquakes. In this work, Rn concentrations in groundwater were continuously measured over a seven-month period, during 2017, in the Giardino Spring, Italy, together with groundwater levels in a nearby well installed into a fractured regional aquifer. Data were processed to reduce noise, and then analyzed to produce the Fourier spectra of Rn concentrations and groundwater levels. These spectra were compared with the spectrum of tidal forces. Results showed that diurnal and semidiurnal cycles of Rn concentrations, and filtered oscillations of groundwater levels, in the nearby well, are correlated with solar and luni-solar components of tidal forces, and suggested no correlation with the principal lunar components. Therefore, influencing factors linked to solar cycles, such as daily oscillations of temperature and atmospheric pressure, and related rock deformations, may have played a role in Rn concentrations and groundwater levels. An open question remains regarding the correlation, which is documented elsewhere, of Rn concentrations and groundwater levels with the lunar components of the solid Earth tides.

scholarly journals ARTIFICIAL INTELLIGENCE TECHNIQUES FOR PREDICTING TIDAL EFFECTS BASED ON GEOGRAPHIC LOCATIONS IN GHANA

2020 ◽  
Vol 46 (1) ◽  
pp. 1-7
Author(s):  
Yakubu Issaka ◽  
Bernard Kumi-Boateng
Keyword(s):  
Artificial Intelligence ◽  
Solid Earth ◽  
Geometric Approach ◽  
Economic Cost ◽  
Multivariate Adaptive Regression Splines ◽  
Earth Tides ◽  
Tidal Effects ◽  
Engineering Structures ◽  
Tidal Forces ◽  
Solid Earth Tides

Tidal forces as a result of attraction of external bodies (Sun, Moon and Stars) through gravity and are a source of noise in many geoscientific field observations. The solid earth tides cause deformation. This deformation results in displacement in geographic positions on the surface of the earth. The displacement due to tidal effects can result in deformation of engineering structures, loss of lives, and economic cost. Tidal forces also help in detecting other environmental and tectonic signals. This study quantifies the effects of solid earth tides on stationary survey controls in five regions of Ghana. The study is in two stages: firstly, the solid earth tides were estimated for each control by a geometric approach (combining Navier’s equation of motion and Love theories). Secondly, estimation using two artificial intelligence methods (Multivariate Adaptive Regression Splines (MARS) and Backpropagation Artificial Neural Network (ANN)). Based on statistical indices of Mean Square Error (MSE) and Correlation Coefficient (R), BPANN, and MARS models can be used as a realistic alternative technique in quantifying solid earth tides for the study area. The MSE and R (MSE; BPANN = 1.3249 × 10–04 and MSE; MARS = 2.2052 × 10–06; R; BPANN = –0.6067 and R; MARS 0.6570) values indicate that MARS outperforms BPANN in quantifying solid earth tides in the study area. BPANN and MARS can be used as an efficient tool for quantifying tidal values based on geographic positions for geodetic deformation studies within the study area.

scholarly journals Short-term tidal variations in UT1: compliance between modelling and observation

2009 ◽  
Vol 5 (H15) ◽  
pp. 215-215 ◽  
Author(s):  
Sigrid Englich ◽  
Harald Schuh ◽  
Robert Weber
Keyword(s):  
Solid Earth ◽  
Earth Tides ◽  
Time Interval ◽  
Observation Data ◽  
Length Of Day ◽  
Tidal Effects ◽  
Short Term ◽  
Solid Earth Tides ◽  
Oceanic Tides ◽  
Tidal Variations

AbstractThe Earth rotation rate and consequently universal time (UT1) and length of day (LOD) are periodically affected by solid Earth tides and oceanic tides. Solid Earth tides induce changes with periods from around 5 days to 18.6 years, with the largest amplitudes occurring at fortnightly, monthly, semi-annual and annual periods, and at 18.6 years. The principal variations caused by oceanic tides have diurnal and semi-diurnal periods. For the investigation of the tidal effects with periods of up to 35 days, UT1 series are estimated from VLBI observation data of the time interval 1984–2008. The amplitudes and phases of the terms of interest are calculated and the results for diurnal and sub-diurnal periods are compared and evaluated with tidal variations derived from a GNSS-based LOD time series of 8 months. The observed tidal signals are finally compared to the predicted tidal variations according to recent geophysical models.

scholarly journals On the Influence of Diurnal and Subdiurnal Signals in the Normal Vector on Large Ring Laser Gyroscope Observations

2020 ◽  
Vol 177 (9) ◽  
pp. 4217-4228
Author(s):  
Monika Tercjak ◽  
André Gebauer ◽  
Marcin Rajner ◽  
Aleksander Brzeziński ◽  
Karl Ulrich Schreiber
Keyword(s):  
Solid Earth ◽  
Ring Laser ◽  
Earth Tides ◽  
Love Numbers ◽  
Ring Laser Gyroscope ◽  
Solid Earth Tides ◽  
Ocean Tidal Loading ◽  
Tidal Loading ◽  
Laser Gyroscope ◽  
The Impact

Abstract The ring laser gyroscope (RLG) technique has been investigated for over 20 years as a potential complement to space geodetic techniques in measuring Earth rotation. However, RLGs are also sensitive to changes in their terrestrial orientation. Therefore in this paper, we review how the high-frequency band (i.e. signals shorter than 0.5 cycle per day) of the known phenomena causing site deformation contribute to the RLG observable, the Sagnac frequency. We study the impact of solid Earth tides, ocean tidal loading and non-tidal loading phenomena (atmospheric pressure loading and continental hydrosphere loading). Also, we evaluate the differences between available models of the phenomena and the importance of the Love numbers used in modeling the impact of solid Earth tides. Finally, we compare modeled variations in the instrument orientation with the ones observed with a tiltmeter. Our results prove that at the present accuracy of the RLG technique, solid Earth tides and ocean tidal loading effects have significant effect on RLG measurements, and continental hydrosphere loading can be actually neglected. Regarding the atmospheric loading model, its application might introduce some undesired signals. We also show that discrepancies arising from the use of different models can be neglected, and there is almost no impact arising from the use of different Love numbers. Finally, we discuss differences between data reduced with tiltmeter observations and these reduced with modeled signal, and potential causes of this discrepancies.

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 Adoption of Empirical Corrections to Woolard's Nutation Theory

1980 ◽  
Vol 78 ◽  
pp. 117-124 ◽  
Author(s):  
D. D. McCarthy ◽  
P. K. Seidelmann ◽  
T. C. Van Flandern
Keyword(s):  
Solid Earth ◽  
Earth Tides ◽  
Earth Model ◽  
Working Standard ◽  
Astronomical Observations ◽  
International Astronomical ◽  
Solid Earth Tides ◽  
Rigid Earth ◽  
Empirical Corrections

Commission 4 of the International Astronomical Union has deferred the question of revisions to the constants and theory of nutation in anticipation that there might be recommendations from Symposium No. 78 in Kiev. The present rigid-Earth theory of nutation does not adequately represent current precise astronomical observations for the major nutation terms. Discrepancies between the presently adopted theory and observations can accumulate to 0″1 in right ascension and significantly affect the determination of UT1 and materially influence the derivation of the new fundamental catalog of star positions and proper motions, FK5 There appears to be no obvious choice for a non-rigid-Earth model at present. The analysis of solid-Earth tides shows nutation coefficients in substantial agreement with astronomical observations and these values have been used in the reduction of radio interferometric and laser ranging observations. In the absence of a non-rigid-Earth model which can satisfy all requirements it is suggested that the coefficients found from the investigation of solid-Earth tides be adopted as a working standard until such a model can be adopted as a basis for nutation.

Viscoelasticity of the lower mantle from forward modeling of normal modes and solid Earth tides

2020 ◽  
Author(s):  
Ulrich Faul ◽  
Harriet Lau
Keyword(s):  
Absorption Band ◽  
Solid Earth ◽  
Lower Mantle ◽  
Normal Modes ◽  
Earth Tides ◽  
Solid Earth Tides ◽  
Anelastic Behavior ◽  
Body Tides ◽  
Anelastic Deformation ◽  
Intrinsic Dissipation

<p>Grain scale diffusive processes are involved in the rheology at convective timescales, but also at the transient timescales of seismic wave propagation, solid Earth tides and post-glacial rebound. Seismic and geodetic data can therefore potentially provide constraints on lower mantle properties such as grain size that are unconstrained otherwise. Current models of the transient viscosity of the lower mantle infer an absorption band of finite width in frequency. Seismic models predict a low frequency end to the absorption band at timescales corresponding to the longest normal modes of about an hour. By contrast, geodetic models infer the onset of an absorption band at these frequencies to cover anelastic deformation at timescales up to 18.6 years. A difficulty in extracting frequency dependence from mode and tide data is its convolution with depth dependence.</p><p>To circumvent this problem we select a distinct set of seismic normal modes and solid Earth body tides that have similar depth sensitivity in the lower mantle. These processes collectively span a period range from 7 minutes to 18.6 years. This allows the examination of frequency dependent energy dissipation over the lower mantle across 6 orders of magnitude. To forward model the transient creep response of the lower mantle we use a laboratory-based model of intrinsic dissipation that we adapt to the lower mantle mineralogy. This extended Burgers model represents an empirical fit to data principally from olivine, but also MgO and other compounds. The underlying microphysical model envisions a sequence of processes that begin with a broad plateau in dissipation at the highest frequencies after the onset of anelastic behavior, followed by a broad absorption band spanning many decades in frequency. The absorption band transitions seamlessly into viscous behavior. Since dissipation both for the absorption band and for (Newtonian) viscous behavior is due to diffusion along grain boundaries there can be no gap between the end of the absorption band and onset of viscous behavior.</p><p>Modeling of the planetary response to small strain excitation necessitates consideration of inertia and self gravitation. The phase lag due to solid Earth body tides therefore does not correspond directly to the intrinsic dissipation measured in the laboratory as material property. We have developed a self consistent theory that combines the planetary response with time-dependent anelastic deformation of rocks. Results from a broad range of forward models show that at lower mantle pressures periods of modes fall onto the broad plateau in dissipation at the onset of anelastic behavior. This explains the apparent frequency independence or even negative frequency dependence observed for some normal modes. At longer timescales, solid Earth tides fall on the frequency-dependent absorption band. This reconciles seemingly contradictory results published by seismic and tidal studies. Observations at even longer timescales are needed to constrain the transition from absorption band to viscous behavior.</p>

scholarly journals Anomalous frequency characteristics of groundwater levels before major earthquakes in Taiwan

2012 ◽  
Vol 9 (6) ◽  
pp. 6979-7000
Author(s):  
C.-H. Chen ◽  
C.-H. Wang ◽  
S. Wen ◽  
T.-K. Yeh ◽  
C.-H. Lin ◽  
...  
Keyword(s):  
Frequency Band ◽  
Barometric Pressure ◽  
Alluvial Fan ◽  
Water Levels ◽  
Earth Tides ◽  
Strong Earthquakes ◽  
Groundwater Levels ◽  
Time Period ◽  
Central Taiwan ◽  
Geomagnetic Anomalies

Abstract. Unusual decreases in water levels were consistently observed in 78% (=42/54) of the wells in the Choshuichi Alluvial Fan of central Taiwan roughly 150 days before the Chi-Chi earthquake (M = 7.6 on 20 September 1999) when the influences of barometric pressure, earth tides, precipitation and artificial pumping were removed. Variations in groundwater levels measured in the anomalous wells between 1 August 1997 and 19 September 1999, the time period covering the unusual decreases, were transferred into the frequency domain to examine anomalous frequency bands associated with the Chi-Chi earthquake. Analytical results show that amplitudes at the frequency band between 0.02 day−1 and 0.04 day−1 were generally maintained at the low stage and were enhanced in the few weeks before the Chi-Chi earthquake. Variations in amplitude within this particular frequency band were further examined in association with earthquakes (M > 6) between 1 August 1997 and 31 December 2009. Enhanced amplitude phenomena are consistently observed prior to the other two earthquakes (the Rei-Li and Ming-Jian earthquakes) during the 12.5 yr, which sheds a promising light on research into precursors of strong earthquakes when combined with other geophysical observations such as geomagnetic anomalies and crustal displacements.

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 ANALYSIS OF THE PRINCIPAL CONSTITUENTS OF SOLID EARTH TIDES ESTIMATED WITH GRAVIMETRIC AND GNSS DATA IN MANAUS AND BRASÍLIA

2019 ◽  
Vol 37 (1) ◽  
pp. 11
Author(s):  
Mário A. de Abreu ◽  
Giuliano S. Marotta ◽  
Lavoisiane Ferreira ◽  
Denizar Blitzkow ◽  
Ana C. O. C. de Matos ◽  
...  
Keyword(s):  
Time Series ◽  
Solid Earth ◽  
Earth Tide ◽  
Earth Tides ◽  
Data Series ◽  
Long Period ◽  
Solid Earth Tides ◽  
Gravimetric Data ◽  
Time Required ◽  
Solid Earth Tide

ABSTRACT. Solid Earth tide is the periodic displacement due to the tidal force. This effect is present in all geodesic and geophysical observations and should be eliminated when high accuracy surveying is required. It is necessary to determine the amplitudes and phases of the harmonic constituents to estimate the terrestrial tide effect magnitude. This article presents a methodology for estimating and analyzing the amplitudes and phases of the solid Earth tide principal constituents from gravimetric/GNSS observations. The methodology was applied to data collected in the Manaus/AM and Brasília/DF stations, Brazil, to determine the amplitude and phase values for the long period, monthly, diurnal and semidiurnal constituents, besides determining the time required for the convergence of the estimated constituent values. The estimated amplitude and phase values, using gravimetric data, converged between the 2nd and 6th months of the time series. For the positioning observations, the constituents values converged between the 2nd and 17th month of the data series, except for the long period constituent, which requires a longer time series to obtain satisfactory values for both methods. The results show that the solid Earth tide constituents were better estimated by the gravimetric data compared to the positioning data considering the series analyzed.Keywords: gravimetry, GNSS, solid Earth tide, tidal constituents.RESUMO. Maré terrestre é o deslocamento periódico decorrente da força de maré. Este é um efeito que deve ser eliminado quando se deseja realizar levantamentos nos quais é necessária alta acurácia tanto em observações geodésicas quanto geofísicas. Para estimar o efeito de maré terrestre deve-se determinar as amplitudes e fases de suas componentes harmônicas. Este artigo apresenta uma metodologia para a estimativa das amplitudes e fases das principais componentes de maré terrestre, a partir de observações gravimétricas/GNSS. A metodologia foi aplicada a dados coletados em estações instaladas em Manaus/AM e Brasília/DF, Brasil, resultando na determinação dos valores de amplitude e fase para componentes de longo período, mensais, diurnas e semidiurnas, além da análise da convergência dos valores estimados para estas componentes. As amplitudes e fases calculadas, utilizando dados gravimétricos, convergiram entre o 2_ e o 6_ mês analisados, enquanto para os dados de posicionamento a convergência ocorreu entre o 2_ e o 17_ mês observado, com exceção da componente de longo período, que não pôde ser determinada em ambos os métodos. Para o período analisado, as componentes de maré terrestre foram melhor estimadas utilizando dados gravimétricos, se comparadas aos resultados obtidos com dados de posicionamento.Palavras-chave: gravimetria, GNSS, maré terrestre, componentes de maré.

scholarly journals Tides and Volcanoes: A Historical Perspective

2021 ◽  
Vol 9 ◽  
Author(s):  
Gianluca Sottili ◽  
Sebastien Lambert ◽  
Danilo Mauro Palladino
Keyword(s):  
Historical Perspective ◽  
Earth Science ◽  
Continental Drift ◽  
Environmental Crisis ◽  
Earth Tides ◽  
Milankovitch Cycles ◽  
Orbital Eccentricity ◽  
Scientific Debate ◽  
Tidal Forces ◽  
Hellenistic World

In this paper, we examine the origins and the history of the hypothesis for an influence of tidal forces on volcanic activity. We believe that exploring this subject through a historical perspective may help geoscientists gain new insights in a field of research so closely connected with the contemporary scientific debate and often erroneously considered as a totally separated niche topic. The idea of an influence of the Moon and Sun on magmatic processes dates back to the Hellenistic world. However, it was only since the late 19th century, with the establishment of volcano observatories at Mt. Etna and Vesuvius allowing a systematic collection of observations with modern methods, that the “tidal controversy” opened one of the longest and most important debates in Earth Science. At the beginning of the 20th century, the controversy assumed a much more general significance, as the debate around the tidal influence on volcanism developed around the formulation of the first modern theories on the origins of volcanism, the structure of the Earth’s interior and the mechanisms for continental drift. During the same period, the first experimental evidence for the existence of the Earth tides by Hecker (Beobachtungen an Horizontalpendeln über die Deformation des Erdkörpers unter dem Einfluss von Sonne und MondVeröffentlichung des Königl, 1907, 32), and the Chamberlin–Moulton planetesimal hypothesis (proposed in 1905 by geologist Thomas Chrowder Chamberlin and astronomer Forest Ray Moulton) about the “tidal” origin of the Solar System, influenced and stimulated new researches on volcano-tides interactions, such as the first description of the “lava tide” at the Kilauea volcano by Thomas Augustus Jaggar in 1924. Surprisingly, this phase of gradual acceptance of the tidal hypothesis was followed by a period of lapse between 1930 to late 1960. A new era of stimulating and interesting speculations opened at the beginning of the seventies of the 20th century thanks to the discovery of the moonquakes revealed by the Apollo Lunar Surface Experiment Package. A few years later, in 1979, the intense volcanism on the Jupiter’s moon Io, discovered by the Voyager 1 mission, was explained by the tidal heating produced by the Io’s orbital eccentricity. In the last part of the paper, we discuss the major advances over the last decades and the new frontiers of this research topic, which traditionally bears on interdisciplinary contributions (e.g., from geosciences, physics, astronomy). We conclude that the present-day debate around the environmental crisis, characterized by a large collection of interconnected variables, stimulated a new field of research around the complex mechanisms of mutual interactions among orbital factors, Milankovitch Cycles, climate changes and volcanism.

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