scholarly journals High-frequency non-tidal ocean loading effects on surface gravity measurements

2008 ◽  
Vol 175 (1) ◽  
pp. 35-45 ◽  
Author(s):  
Jean Paul Boy ◽  
Florent Lyard
Keyword(s):  
High Frequency ◽  
Surface Gravity ◽  
Gravity Measurements ◽  
Loading Effects ◽  
Ocean Loading

Observation of gravity fluctuations due to tide-induced groundwater table fluctuations with two superconducting gravimeters

2020 ◽  
Author(s):  
Hiroki Goto ◽  
Mituhiko Sugihara ◽  
Yuji Nishi ◽  
Hiroshi Ikeda
Keyword(s):  
Groundwater Level ◽  
Hydraulic Properties ◽  
Groundwater Resources ◽  
Groundwater Table ◽  
Surface Gravity ◽  
Superconducting Gravimeters ◽  
Loading Effects ◽  
Ocean Loading ◽  
Aquifer Properties ◽  
The Difference

<p>Estimation of aquifer hydraulic properties is necessary for predicting groundwater flow and hence managing groundwater resources. Analysis of tide-induced groundwater table fluctuations in unconfined aquifers is one of the methods to estimate aquifer properties. Changes in groundwater level affect surface gravity. Consequently, surface gravity in coastal regions is expected to fluctuate due to the groundwater table fluctuations and is potentially useful for estimating aquifer properties. Moreover, gravity measurements are sensitive to mass redistribution around the observation location and therefore are useful for estimating the storage coefficient of an aquifer. In this study, surface gravity and unconfined groundwater level were measured continuously near the coast of Japan to observe gravity fluctuations due to the tide-induced groundwater table fluctuations. Groundwater level measured in two wells at 60 and 90 m distances from the coastline fluctuated in response to ocean tides. Two superconducting gravimeters (SGs) were installed at 70 and 80 m distances from the coastline and at an elevation of 8 m. After taking the difference between gravity values recorded with the two SGs and then correcting the gravity difference for ocean loading effects, diurnal and semi-diurnal gravity fluctuations, which are possibly due to tide-induced groundwater table fluctuations, were recognized. These results suggest that gravity monitoring with two SGs at different distances from the coastline can be useful for observing gravity fluctuations due to tide-induced groundwater table fluctuations and possibly for estimating aquifer hydraulic properties.</p>

Improving corrections in microgravimetric surveys through modelling of ocean loading effects

1998 ◽  
Author(s):  
M. Llubes ◽  
J. Hinderer ◽  
M. Amalvict ◽  
M. F. Lalancette-Le Quentrec
Keyword(s):  
Loading Effects ◽  
Ocean Loading

A Discussion on the measurement and interpretation of changes of strain in the Earth - An improved servo-controlled tiltmeter system and latest measurements in Sweden

1973 ◽  
Vol 274 (1239) ◽  
pp. 305-309 ◽  
Keyword(s):  
Pressure Effects ◽  
Land Uplift ◽  
Bearing Plate ◽  
Tidal Forces ◽  
Mercury Column ◽  
First Results ◽  
Loading Effects ◽  
Ocean Loading ◽  
Servo Signal ◽  
Horizontal Pendulum

Two serious shortcomings in horizontal pendulums used for tilt measurements are nonlinearity in their response to tilt and sensitivities which vary with time. These difficulties may be eliminated if a horizontal pendulum is used as a null indicator. A description is given of a horizontal pendulum apparatus which automatically compensates for ground tilt. The pendulum apparatus is designed so that it may be tilted by varying the pressure in an expansible bearing plate made of stainless steel which is placed at its base. Pressure changes are produced in the bearing plate by varying the height of a column of mercury, a process which can be previously calibrated with great precision. The position of the pendulum beam is sensed by an electro-optical transducer which provides a suitable servo signal to adjust the height of the mercury column when the instrument undergoes tilting. The servo signal can be recorded directly on an ink chart recorder or digitally. First results have been obtained in a test station. It is planned to establish an array of geodynamic stations in Scandinavia incorporating these tiltmeters alongside recording gravity meters in order to study crustal movements by tidal forces, atmospheric pressure effects, ocean loading effects and possibly the process of land uplift in Fennoscandia.

scholarly journals Non-tidal ocean loading effects on geodetic GPS heights

2011 ◽  
Vol 38 (9) ◽  
pp. n/a-n/a ◽  
Author(s):  
S. D. P. Williams ◽  
N. T. Penna
Keyword(s):  
Loading Effects ◽  
Ocean Loading

scholarly journals Estimation of Bouguer correction density based on underground and surface gravity measurements and precise modelling of topographic effects – two case studies from Slovakia

2018 ◽  
Vol 48 (4) ◽  
pp. 319-336 ◽  
Author(s):  
Pavol Zahorec ◽  
Juraj Papčo
Keyword(s):  
Laser Scanning ◽  
Airborne Lidar ◽  
Surface Gravity ◽  
Karst Area ◽  
Topographic Effects ◽  
Railway Tunnel ◽  
Detailed Surface ◽  
Active Coal ◽  
Gravity Measurements ◽  
Gravimetric Modelling

Abstract We present a simple and straightforward method for estimating the mean density of topographic masses based on underground gravity measurements along with topography modelling. Two examples under different conditions are given, the first coming from a railway tunnel passing through a Mesozoic karst area and the second from an active coal mine situated in a Neogene sedimentary basin. Relative gravity measurements were processed and corrected by topographic effect modelling based on high-precision airborne LiDAR-derived elevation models. In addition, detailed mining tunnel gravimetric modelling based on terrestrial laser scanning data is presented. Resulted mean (bulk) densities are compared with those obtained from detailed surface gravity measurements as well as with available rock-samples density analysis.

CORRELATING SEA‐SURFACE AND AERIAL GRAVITY MEASUREMENTS

Geophysics ◽  
1966 ◽  
Vol 31 (1) ◽  
pp. 264-266 ◽  
Author(s):  
Stephen Thyssen‐Bornemisza
Keyword(s):  
Ground Surface ◽  
Sea Surface ◽  
Surface Gravity ◽  
Sea Floor ◽  
Gravity Measurements ◽  
Vertical Gradients

When sea‐surface gravity observations were supplemented by corresponding values from the airborne meter, average vertical gradients of gravity could be computed. In a borehole these gradients are observable by moving the borehole gravity meter up and down to another level (Thyssen‐Bornemisza, 1963, 1964, 1965a), but measurements taken on two horizontal profiles separated by the constant vertical interval h could furnish only relative gradient values or variations in the profile direction. Of course, gravity profiles on the ground surface or the sea floor can be likewise supplemented by aerial observations.

Modeling and Reliability Analysis of TSVs for High Frequency Applications

2013 ◽  
Vol 2013 (1) ◽  
pp. 000245-000249 ◽  
Author(s):  
Kaushal Kannan ◽  
Bruce Kim ◽  
Sukeshwar Kannan ◽  
Seok-Ho Noh
Keyword(s):  
Crack Length ◽  
Reliability Analysis ◽  
Output Power ◽  
High Frequency ◽  
Electrical Performance ◽  
Finite Element Models ◽  
Electrical Modeling ◽  
Mechanical Models ◽  
Loading Effects ◽  
Rf Signal

This paper presents electrical modeling of thermo-mechanical delamination in TSV. Previously, several papers in electrical modeling of TSV have been published in open literature; however, these do not consider the thermal-mechanical delamination in TSV. Stress-induced thermo-mechanical delamination in TSV has been analyzed by considering the thermo-mechanical stress loading effects of high aspect ratio copper electroplated TSVs. Two-dimensional mechanical finite element models have been built to analyze the stress distribution in TSV structures. The mechanical models and energy release rate at the crack are then translated to electrical defect models to evaluate the functional electrical performance of TSVs with delaminations. Simulation was performed on 7 μm by 60 μm TSVs using an RF signal with −10 dBm power on a crack length of 0.2 um and width of 0.15 um. We observed output power of −11.8 dB at a frequency of 77 GHz. When the crack length was increased, the output power decreased to −11.2 dBm due to increased parasitics resulting in more attenuation of RF output. This reliability analysis enables us to evaluate the electrical performance of TSVs for high frequency applications.

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