Horizontal/vertical displacements and their rates

2021 ◽  
pp. 182-198
Author(s):  
Jean-Luc Bouchez ◽  
Adolphe Nicolas
Keyword(s):  
Rotation Axis ◽  
Spherical Surface ◽  
Radioactive Decay ◽  
Horizontal Displacement ◽  
Glacial Rebound ◽  
Uplift Rates ◽  
Vertical Displacements ◽  
Order Of Magnitude ◽  
Mid Atlantic Ridge ◽  
Fixed Reference

This chapter widens our scope towards translation and rotation. These displacements are critical in tectonic studies along with distortion, which has so far been the main subject of this book. Note that a translation needs a fixed reference to be defined. Consider, for example, the glide of the lithosphere over the asthenosphere with respect to the mid-Atlantic ridge. On a spherical surface, a translation is also a rotation, where the horizontal displacement of a plate is governed by a rotation axis (or pole) and an angular velocity. Vertical displacements of the Earth’s surface are one order of magnitude less (on the order of mm per year) than horizontal displacements. Lots of studies, performed in the frame of a discipline called neotectonics, attempt to determine uplift rates through different techniques, such as fission track and radioactive decay. They will be briefly presented in this chapter. The main reference for vertical displacements is the sea level, which itself is mobile through time. This mobility is obviously sensitive when processes such as erosion or post-glacial rebound are considered, but much less significant when exhumation of deep-seated rocks may reach kilometres during an orogeny.

Absolute Measurement of Aspheric Surfaces Using White-Light Interferometry

2007 ◽  
Vol 364-366 ◽  
pp. 80-85
Author(s):  
Su Ping Chang ◽  
Tie Bang Xie ◽  
Xuang Ze Wang ◽  
Jun Guo
Keyword(s):  
High Precision ◽  
White Light ◽  
Spherical Surface ◽  
Three Dimensional ◽  
Influence Factors ◽  
Horizontal Displacement ◽  
Absolute Measurement ◽  
Aspheric Surfaces ◽  
Interferometric Technique ◽  
Main Influence

White-light interferometric technique has been widely applied in the measurement of three-dimensional profiles and roughness with high-precision. Based on the characteristic of interferometric technique, a new method combined with image location and a three-dimensional stage is proposed to achieve the non-contact absolute shape measurement for aspheric and spherical surface in a slarge range. The interference fringes vary with the horizontal displacement of the measured surface, the surface information was obtained by locating the transformation of the maximal intensity in the interferograms. Two main influence factors are discussed; they are performance of the inerferimetric microscope and the stage. Since the performance of the stage directly determines the measurement precision, a three-dimensional displacement stage with a large range and a high precision was developed. Some experiments were carried out to verify the performance of the three-dimensional displacement stage and the validity of the new measurement method with satisfactory results.

scholarly journals Differences in channel and hillslope geometry record a migrating uplift wave at the Mendocino triple junction, California, USA

Geology ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 184-188 ◽  
Author(s):  
Fiona J. Clubb ◽  
Simon M. Mudd ◽  
Martin D. Hurst ◽  
Stuart W.D. Grieve
Keyword(s):  
Triple Junction ◽  
Land Surface ◽  
Plate Motion ◽  
Topographic Analysis ◽  
Channel Response ◽  
Mendocino Triple Junction ◽  
Uplift Rates ◽  
Order Of Magnitude ◽  
Landscape Morphology ◽  
Channel Steepness

Abstract Tectonic plate motion, and the resulting change in land surface elevation, has been shown to have a fundamental impact on landscape morphology. Changes to uplift rates can drive a response in fluvial channels, which then drives changes to hillslopes. Because hillslopes respond on different time scales than fluvial channels, investigating the geometry of channels and hillslopes in concert provides novel opportunities to examine how uplift rates may have changed through time. Here we perform coupled topographic analysis of channel and hillslope geometry across a series of catchments at the Mendocino triple junction (MTJ) in northern California, USA. These catchments are characterized by an order-of-magnitude difference in uplift rate from north to south. We find that dimensionless hillslope relief closely matches the uplift signal across the area and is positively correlated with channel steepness. Furthermore, the range of uncertainty in hillslope relief is lower than that of channel steepness, suggesting that it may be a more reliable recorder of uplift in the MTJ region. We find that hilltop curvature lags behind relief in its response to uplift, which in turn lags behind channel response. These combined metrics show the northward migration of the MTJ and the corresponding uplift field from topographic data alone.

scholarly journals Chronological reflection on monitoring urban areas subsidence due to groundwater extraction

2019 ◽  
Vol 85 ◽  
pp. 07015 ◽  
Author(s):  
Alina Radutu ◽  
Radu Constantin Gogu
Keyword(s):  
Land Subsidence ◽  
Urban Areas ◽  
Urban Expansion ◽  
Groundwater Withdrawal ◽  
Groundwater Extraction ◽  
Monitoring Methods ◽  
Vertical Displacements ◽  
Order Of Magnitude ◽  
History Of ◽  
Subsidence Monitoring

Land subsidence affects urban areas worldwide. Sometimes it could be driven by intensive groundwater withdrawal to assure different urban needs and functionalities. Some of these urban areas have a long history of subsidence that covers almost a century. The aim of this paper is to present the evolution of several urban areas affected by land subsidence, the methods used to monitor vertical displacements along the decades in relationship to the groundwater extraction associated to the urban expansion, and the mitigation techniques used for countering the effects of intensive groundwater withdrawal. Even the originally applied subsidence monitoring methods (such as geometric levelling) are still very sensitive, in terms of time consuming, covered area, and financial effort, these methods might be complemented by new methods based on Synthetic Aperture Radar Interferometry (InSAR). InSAR methods show also a significant progress during the last decades when considering the subsidence sensed order of magnitude.

scholarly journals Reassessment of the radiocesium resuspension flux from contaminated ground surfaces in East Japan

2021 ◽  
Author(s):  
Mizuo Kajino ◽  
Akira Watanabe ◽  
Masahide Ishizuka ◽  
Kazuyuki Kita ◽  
Yuji Zaizen ◽  
...  
Keyword(s):  
Land Surface ◽  
Heavy Traffic ◽  
Inhalation Exposure ◽  
Radioactive Decay ◽  
Ground Surface ◽  
Road Dust ◽  
Bare Soil ◽  
Air Concentration ◽  
Deposition Rates ◽  
Order Of Magnitude

Abstract. Resuspension of 137Cs from the contaminated ground surface to the atmosphere is essential for understanding the environmental behaviors of 137Cs and estimating external and inhalation exposure of residents. Kajino et al. (2016) assessed the 137Cs resuspension flux from bare soil and forest ecosystems in East Japan in 2013 using a numerical simulation constrained by surface air concentration measurements. However, the simulation was found to underestimate the observed deposition amounts by two orders of magnitude. The reason for this underestimation is that the simulation assumed that resuspended 137Cs is carried by submicron aerosols, which have low deposition rates. Based on the observational indications that soil dust and bioaerosols are the major carriers of resuspended 137Cs, a new simulation is performed with higher deposition rates constrained by both surface concentrations and deposition amounts. In the new estimation, the areal total annual resuspension of 137Cs in 2013 is 25.7 TBq, which is equivalent to 0.96 % of the initial deposition (2.68 PBq). Due to the rapid deposition rates, the annual redeposition amount is also large at 10.6 TBq, approximately 40 % of the resuspended 137Cs. The resuspension rate through the atmosphere (0.96 % y−1) seems slow, but it (2.6 × 10−5 d−1) may not be negligibly small compared to the actual decreasing trend of the ambient gamma dose rate obtained in Fukushima Prefecture after the radioactive decay of 137Cs plus 134Cs in 2013 is subtracted (1.0–7.9 × 10−4 d−1): Resuspension can account for 1–10 % of the decreasing rate due to decontamination and natural decay through land surface processes. The current simulation underestimated the 137Cs deposition in Fukushima city in winter by more than an order of magnitude, indicating the presence of additional resuspension sources. The site of Fukushima city is surrounded by major roads. Heavy traffic on wet and muddy roads after snow removal operations could generate superlarge (approximately 100 µm in diameter) road dust or road salt particles, which is not included in the model but might contribute to the observed 137Cs at the site.

scholarly journals The Integration of Two Interferometric Radars for Measuring Dynamic Displacement of Bridges

2021 ◽  
Vol 13 (18) ◽  
pp. 3668
Author(s):  
Piotr Olaszek ◽  
Andrzej Świercz ◽  
Francesco Boscagli
Keyword(s):  
Longitudinal Vibration ◽  
Experimental Tests ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
High Accuracy ◽  
Vertical Vibration ◽  
Remote Measurement ◽  
Railway Bridges ◽  
Vertical Displacements ◽  
Horizontal Displacements

Measurements of displacements of bridges under dynamic load are particularly difficult in the case of structures where access to the area under the tested structure is impossible. Then, remote measurement methods are preferred, such as interferometric radar. Interferometric radar has high accuracy when measuring displacement in the direction of its target axis. The problems appear when a bridge vibrates in two directions: horizontal (lateral or longitudinal) and vertical. The use of one radar to measure those vibrations may be impossible. This paper presents the application of a set of two interferometric radars to measure vertical vibration and horizontal longitudinal vibration with high accuracy. The method was positively verified by experimental tests on two railway bridges characterized by different levels of horizontal displacement. The accuracy of the radar measurements was tested by the direct measurement of vertical displacements using inductive gauges. In conclusion, in the case of vertical displacement measurements using one interferometric radar, the influence of horizontal displacements should be excluded. In the case of locating radars at the area of bridge supports, it is necessary to either use a set of two radars or first investigate the magnitude of possible horizontal displacements in relation to vertical displacements.

scholarly journals Temporal Characteristics of Abyssal Finescale Motions above Rough Bathymetry

2007 ◽  
Vol 37 (3) ◽  
pp. 409-427 ◽  
Author(s):  
John M. Toole
Keyword(s):  
Wave Interaction ◽  
Internal Tides ◽  
Wave Radiation ◽  
Diapycnal Mixing ◽  
Turbulent Dissipation ◽  
Wave Ray ◽  
Order Of Magnitude ◽  
Mid Atlantic Ridge ◽  
Temperature Shear ◽  
Additional Support

Abstract Current-meter data from a two-year mooring within a fracture zone on the western flank of the Mid-Atlantic Ridge in the South Atlantic Ocean are reported. The mooring, deployed in conjunction with the Brazil Basin Tracer Release Experiment, was placed in the general area where enhanced diapycnal mixing had previously been inferred. The current-meter data characterize the velocity, temperature, shear, and temperature gradient variability as a function of frequency. Energetic velocities and shears were observed at the mooring at a variety of frequencies. In addition to semidiurnal flows, a significant amount of shear variance derived from near-inertial motions, as has been seen in a recent numerical modeling study of tidal-frequency internal wave radiation and wave–wave interaction. At times, a fortnightly modulation of the total superinertial shear variance was indicated in the data, but this signal did not dominate the records. Wave ray tracing indicates that the deeper current meters may have been placed in a shadow zone for locally generated internal tides. At shallower levels, it is suggested that dispersion, wave–wave interaction, and wave breaking effectively obscured the sources of the finescale energy. Average diapycnal diffusivity estimates inferred from a Richardson-number-based parameterization and from observations of temperature inversions at 4648 m were of the same order of magnitude as those derived from turbulent dissipation estimates and from the rate of diapycnal tracer dispersion. The mooring data thus add additional support to the idea that energetic finescale motions above rough bathymetry support enhanced turbulent diapycnal mixing in these regions.

scholarly journals The turbulent/non-turbulent interface bounding a far wake

2002 ◽  
Vol 451 ◽  
pp. 383-410 ◽  
Author(s):  
DAVID K. BISSET ◽  
JULIAN C. R. HUNT ◽  
MICHAEL M. ROGERS
Keyword(s):  
Large Scale ◽  
Turbulence Models ◽  
Passive Scalar ◽  
Reynolds Stresses ◽  
Mean Velocity ◽  
Velocity Fluctuations ◽  
Eddy Motion ◽  
Order Of Magnitude ◽  
Fixed Reference ◽  
Velocity Variances

The velocity fields of a turbulent wake behind a flat plate obtained from the direct numerical simulations of Moser et al. (1998) are used to study the structure of the flow in the intermittent zone where there are, alternately, regions of fully turbulent flow and non-turbulent velocity fluctuations on either side of a thin randomly moving interface. Comparisons are made with a wake that is ‘forced’ by amplifying initial velocity fluctuations. A temperature field T, with constant values of 1.0 and 0 above and below the wake, is transported across the wake as a passive scalar. The value of the Reynolds number based on the centreplane mean velocity defect and half-width b of the wake is Re ≈ 2000.The thickness of the continuous interface is about 0.07b, whereas the amplitude of fluctuations of the instantaneous interface displacement yI(t) is an order of magnitude larger, being about 0.5b. This explains why the mean statistics of vorticity in the intermittent zone can be calculated in terms of the probability distribution of yI and the instantaneous discontinuity in vorticity across the interface. When plotted as functions of y−yI the conditional mean velocity 〈U〉 and temperature 〈T〉 profiles show sharp jumps at the interface adjacent to a thick zone where 〈U〉 and 〈T〉 vary much more slowly.Statistics for the conditional vorticity and velocity variances, available in such detail only from DNS data, show how streamwise and spanwise components of vorticity are generated by vortex stretching in the bulges of the interface. While mean Reynolds stresses (in the fixed reference frame) decrease gradually in the intermittent zone, conditional stresses are roughly constant and then decrease sharply towards zero at the interface. Flow fields around the interface, analysed in terms of the local streamline pattern, confirm and explain previous results that the advancement of the vortical interface into the irrotational flow is driven by large-scale eddy motion.Terms used in one-point turbulence models are evaluated both conventionally and conditionally in the interface region, and the current practice in statistical models of approximating entrainment by a diffusion process is assessed.

scholarly journals The largest Crab glitch and the vortex creep model

2019 ◽  
Vol 488 (2) ◽  
pp. 2275-2282 ◽  
Author(s):  
Erbil Gügercinoğlu ◽  
M Ali Alpar
Keyword(s):  
Rotation Axis ◽  
Creep Model ◽  
X Rays ◽  
Creep Response ◽  
Plate Size ◽  
Order Of Magnitude ◽  
Outward Motion ◽  
The Common ◽  
First Time ◽  
High Cadence

Abstract The Crab pulsar displayed its largest glitch on 2017 November. An extended initial spin-up phase of this largest glitch was resolved, for the first time with high cadence of observations both in radio and X-rays on a time-scale of 2 d. A combination of crustquake and vortex unpinning models is invoked to account for the extended spin-up, magnitude, and post-glitch relaxation characteristics of this glitch. We evaluate the extended spin-up followed by the familiar spin-down as due to the creep response to the initial induced inward motion of some vortex lines pinned to broken crustal plates moving inward towards the rotation axis, together with the common and familiar post-glitch creep response to the sudden outward motion of vortices unpinned at the glitch. Our analysis confirms that the number of unpinned vortices participating in glitches are similar in all Crab glitches, and within an order of magnitude in all glitches from all pulsars. This typical number of unpinned vortices is related to the broken plate size in quakes as triggers for vortex unpinning avalanches. The physical determinant of this universal broken plate size is in turn the critical strain angle in the neutron star crust. Occurrence of this largest Crab glitch after a relatively long inactive period is consistent with accumulation of the pinned vorticity to be tapped.

Scaling Analysis for the Liquefaction Phenomena Induced by Water Waves

2016 ◽  
Author(s):  
E. Arcos ◽  
E. Bautista ◽  
F. Méndez
Keyword(s):  
Governing Equation ◽  
Analytical Solutions ◽  
Water Waves ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Scaling Analysis ◽  
Governing Equations ◽  
Order Of Magnitude ◽  
Characteristic Scales

In this work an scaling analysis of the liquefaction phenomena is presented. The characteristic scales are obtained by balancing term by term of the well known partial dynamics governing equations (approximation U – P). The order of magnitude of the horizontal displacement are very smaller compared with the vertical displacement and therefore the governing equation are only a function of the dependent vertical variables. The U – P approximation is reduced and presented in its dimensionless version. This scaling analysis can be used to obtain analytical solutions of the liquefaction phenomena under the action of the water waves.

scholarly journals Observational constraints on the likelihood of 26Al in planet-forming environments

2020 ◽  
Vol 644 ◽  
pp. L1
Author(s):  
Megan Reiter
Keyword(s):  
Solar System ◽  
Planet Formation ◽  
Radioactive Decay ◽  
High Mass ◽  
Mass Star ◽  
Early Solar System ◽  
Star Forming ◽  
Star Forming Regions ◽  
The Galaxy ◽  
Order Of Magnitude

Recent work suggests that 26Al may determine the water budget in terrestrial exoplanets as its radioactive decay dehydrates planetesimals leading to rockier compositions. Here I consider the observed distribution of 26Al in the Galaxy and typical star-forming environments to estimate the likelihood of 26Al enrichment during planet formation. I do not assume Solar-System-specific constraints as I am interested in enrichment for exoplanets generally. Observations indicate that high-mass stars dominate the production of 26Al with nearly equal contributions from their winds and supernovae. Observed 26Al abundances are comparable to those in the early Solar System in the high-mass star-forming regions where most stars (and thereby most planets) form. These high abundances appear to be maintained for a few million years, which is much longer than the 0.7 Myr half-life. Observed bulk 26Al velocities are an order of magnitude slower than expected from winds and supernovae. These observations are at odds with typical model assumptions that 26Al is provided instantaneously by high velocity mass loss from supernovae and winds. The regular replenishment of 26Al, especially when coupled with the small age differences that are common in high-mass star-forming complexes, may significantly increase the number of star- and planet-forming systems exposed to 26Al. Exposure does not imply enrichment, but the order of magnitude slower velocity of 26Al may alter the fraction that is incorporated into planet-forming material. Together, this suggests that the conditions for rocky planet formation are not rare, nor are they ubiquitous, as small regions such as Taurus, that lack high-mass stars to produce 26Al may be less likely to form rocky planets. I conclude with suggested directions for future studies.

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