![A. Wegener's idea of drifting continents [2].](https://www.researchgate.net/profile/Jan-Mestan/publication/360312991/figure/fig1/AS:1151238775279616@1651488121022/A-Wegeners-idea-of-drifting-continents-2_Q320.jpg)
![O. C. Hilgenberg's idea of the Earth getting bigger [3].](https://www.researchgate.net/profile/Jan-Mestan/publication/360312991/figure/fig2/AS:1151238775279618@1651488121226/O-C-Hilgenbergs-idea-of-the-Earth-getting-bigger-3_Q320.jpg)
![NNR-NUVEL-1A geological model visualized by authors from The University of Texas at Austin, Jackson School of Geosciences. Maximum velocities are 10.4 cm/year [15].](https://www.researchgate.net/profile/Jan-Mestan/publication/360312991/figure/fig3/AS:1151238775291906@1651488121282/NNR-NUVEL-1A-geological-model-visualized-by-authors-from-The-University-of-Texas-at_Q320.jpg)
![Horizontal velocities from NAREF cumulative solution [17].](https://www.researchgate.net/profile/Jan-Mestan/publication/360312991/figure/fig4/AS:1151238775291907@1651488121351/Horizontal-velocities-from-NAREF-cumulative-solution-17_Q320.jpg)
![Horizontal velocities from NAREF cumulative solution after removal of ITRF2005 plate motion [17].](https://www.researchgate.net/profile/Jan-Mestan/publication/360312991/figure/fig5/AS:1151238775279629@1651488121391/Horizontal-velocities-from-NAREF-cumulative-solution-after-removal-of-ITRF2005-plate_Q320.jpg)
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Horizontal Tectonics of the North America Region: A Brief Review of the ITRF
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Abstract and Figures
Plate-fixed and Earth-fixed measurement chain concepts were briefly described and explained. It was shown that the International Terrestrial Reference Frame (ITRF) contains a fundamental inconsistency, which is its alignment to plate tectonics geological models, e.g. to the NNR-NUVEL-1A in the ITRF2000. The Global Positioning System (GPS) is fundamentally an example of an Earth-fixed measurement chain concept and has enabled to detect global tectonic motions of the Earth's crust at an accuracy of a few millimeters in the last decades. Results of long-term GPS monitoring networks such as The North America Reference Frame (NAREF) provide high accuracy fields of horizontal motions in the Earth's crust. When the ITRF is put into practice, these horizontal motions radically change into a field of highly coordinated longer (plate) velocity vectors. This highly coordinated vector field is in fact created by an erroneous, fully independent and man-made plate motion model added into the ITRF by using a subroutine. A true global GPS velocity field can be obtained, paradoxically, by a removal of the ITRF plate motion model from the ITRF velocity field. This operation offers an insight into the Earth-fixed behavior of the Earth's crust and also falsifies the highly coordinated artificial plate tectonic motions.
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1-sentence-abstract:
The measured LLR return signals fit to measurements to the bear surface of the Moon and not to retroreflectors. -----------------
This paper provides an overview of the Lunar Laser Ranging (LLR) experiments. The measurement principle is explained and its theory is derived. Both contributions, the direct reflected light from retroreflectors as well as the scattered light from the lunar surface are considered. The measurement results from the Sixties until 2007 are then compared between different LLR stations and with the theoretical forecast. The very first experiment was in 1962: a laser beam was directed to the Moon and the scattered light from the lunar surface was detected. The number of received photons was in line with the theory. Then from 1969 the laser beams were directed to retroreflectors placed by Apollo astronauts and Luna space crafts. Retroreflectors are on the one hand reference points for long term measurements; on the other hand they deliver a much stronger return signal compared to the scattered return. But none of the stations could measure the expected amplification of the retroreflectors. The number of received photons remained in line with measurements to the bare surface of the Moon. Therefore either all retroreflectors have degraded such that their return signals fit to the scattered return from the lunar soil or the measurements were indeed taken to the lunar surface only.
Unlike the past International Terrestrial Reference Frame (ITRF) versions where global long-term solutions were combined, the ITRF2005 uses as input data time series (weekly from satellite techniques and 24-h session-wise from Very Long Baseline Interferometry) of station positions and daily Earth Orientation Parameters (EOPs). The advantage of using time series of station positions is that it allows to monitor station non-linear motion and discontinuities and to examine the temporal behavior of the frame physical parameters, namely the origin and the scale. The ITRF2005 origin is defined in such a way that it has zero translations and translation rates with respect to the Earth center of mass, averaged by the Satellite Laser Ranging (SLR) time series spanning 13 years of observations. Its scale is defined by nullifying the scale and its rate with respect to the Very Long Baseline Interferometry (VLBI) time series spanning 26 years of observations. The ITRF2005 orientation (at epoch 2000.0) and its rate are aligned to the ITRF2000 using 70 stations of high geodetic quality. The estimated level of consistency of the ITRF2005 origin (at epoch 2000.0) and its rate with respect to the ITRF2000 is respectively 0.1, 0.8, 5.8 mm and 0.2, 0.1, 1.8 mm/yr along the X, Y and Z-axis. We estimate the formal errors on these components to be 0.3 mm and 0.3 mm/yr. We believe that this low level of agreement between the two frame origins is most probably due to the poor SLR network geometry and its degradation over time. The ITRF2005 combination involving 84 co-location sites revealed a scale inconsistency of 1 ppb (6.3 mm at the equator), at epoch 2000.0, and 0.08 ppb/yr between the SLR and VLBI long-term solutions as obtained by the stacking of their respective time series. Possible causes of this inconsistency may include the poor SLR and VLBI networks and their co-locations, local tie uncertainties, systematic effects and possible inconsistent model corrections used in the data analysis of both techniques. For the first time of the ITRF history, the ITRF2005 rigorous combination provides self-consistent series of EOPs, including Polar Motion from VLBI and satellite techniques and Universal Time and Length of Day from VLBI only. A velocity field of 152 sites with an error less than 1.5 mm/yr is used to estimate absolute rotation poles of 15 tectonic plates that are consistent with the ITRF2005 frame. This new absolute plate motion model supersedes and significantly improves that of the ITRF2000 which involved six major tectonic plates.
Recent revisions to the geomagnetic time scale indicate that global plate motion model NUVEL-1 should be modified for comparison with other rates of motion including those estimated from space geodetic measurements. The optimal recalibration, which is a compromise among slightly different calibrations appropriate for slow, medium, and fast rates of seafloor spreading, is to multiply NUVEL-1 angular velocities by a constant, α, of 0.9562. We refer to this simply recalibrated plate motion model as NUVEL-1A, and give correspondingly revised tables of angular velocities and uncertainties. Published work indicates that space geodetic rates are slower on average than those calculated from NUVEL-1 by 6±1%. This average discrepancy is reduced to less than 2% when space geodetic rates are instead compared with NUVEL-1A.
For the first time in the history of the International Terrestrial Reference Frame, the ITRF2000 combines unconstrained space geodesy solutions that are free from any tectonic plate motion model. Minimum constraints are applied to these solutions solely in order to define the underlying terrestrial reference frame (TRF). The ITRF2000 origin is defined by the Earth center of mass sensed by satellite laser ranging (SLR) and its scale by SLR and very long baseline interferometry. Its orientation is aligned to the ITRF97 at epoch 1997.0, and its orientation time evolution follows, conventionally, that of the no-net-rotation NNR-NUVEL-1A model. The ITRF2000 orientation and its rate are implemented using a consistent geodetic method, anchored over a selection of ITRF sites of high geodetic quality, ensuring a datum definition at the 1 mm level. This new frame is the most extensive and accurate one ever developed, containing about 800 stations located at about 500 sites, with better distribution over the globe compared to past ITRF versions but still with more site concentration in western Europe and North America. About 50% of station positions are determined to better than 1 cm, and about 100 sites have their velocity estimated to at (or better than) 1 mm/yr level. The ITRF2000 velocity field was used to estimate relative rotation poles for six major tectonic plates that are independent of the TRF orientation rate. A comparison to relative rotation poles of the NUVEL-1A plate motion model shows vector differences ranging between 0.03° and 0.08°/m.y. (equivalent to approximately 1-7 mm/yr over the Earth's surface). ITRF2000 angular velocities for four plates, relative to the Pacific plate, appear to be faster than those predicted by the NUVEL-1A model. The two most populated plates in terms of space geodetic sites, North America and Eurasia, exhibit a relative Euler rotation pole of about 0.056 (+/-0.005)°/m.y. faster than the pole predicted by NUVEL-1A and located about (10°N, 7°E) more to the northwest, compared to that model.
Space geodesy data are used to verify whether plates move chaotically or rather follow a sort of tectonic mainstream. While independent lines of geological evidence support the existence of a global ordered flow of plate motions that is westerly polarized, the Terrestrial Reference Frame (TRF) presents limitations in describing absolute plate motions relative to the mantle. For these reasons we jointly estimated a new plate motions model and three different solutions of net lithospheric rotation. Considering the six major plate boundaries and variable source depths of the main Pacific hotspots, we adapted the TRF plate kinematics by global space geodesy to absolute plate motions models with respect to the mantle. All three reconstructions confirm (i) the tectonic mainstream and (ii) the net rotation of the lithosphere. We still do not know the precise trend of this tectonic flow and the velocity of the differential rotation. However, our results show that assuming faster Pacific motions, as the asthenospheric source of the hotspots would allow, the best lithospheric net rotation estimate is 13.4 ± 0.7 cm yr−1. This superfast solution seems in contradiction with present knowledge on the lithosphere decoupling, but it matches remarkably better with the geological constraints than those retrieved with slower Pacific motion and net rotation estimates. Assuming faster Pacific motion, it is shown that all plates move orderly ‘westward’ along the tectonic mainstream at different velocities and the equator of the lithospheric net rotation lies inside the corresponding tectonic mainstream latitude band (≈±7°), defined by the 1σ confidence intervals.
An instantaneous plate-motion model, Relative Motion 2 (RM2), is obtained by inverting a data set comprising 110 spreading rates, 78 transform fault azimuths, and 142 earthquake slip vectors. RM2 is compared with angular velocity vectors which best fit the data along individual plate boundaries and, while the model performs close to optimally in most regions, attention is directed to those regions which are not suitably described by the model. Reasons for the discrepancies between RM2 and observations for the India-Antarctica plate boundary, the Pacific-India plate boundary, and the east-west trending transform fault azimuths observed in the French-American Mid-Ocean Undersea Study area are discussed.
This book is an attempt to present a global picture of modern science within the framework of the origin and evolution of the world in which we live. It provides the background necessary to understand why our planet is at risk. It also provides the background necessary for devising ways to stabilize the planet. The treatment is quantitative and rigorous throughout. The emphasis is on facts, figures, quantities, and interrelationships. Contents: 1. Prolegomena: science and religion. 2. Matter and energy. 3. Cosmology. 4. Geology. 5. Evolution of life and environment. 6. The historical perspective. 7. Appendixes.
The Two Earths of Erastothenes
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Carlos CC. The Two Earths of Erastothenes. Isis. 2015; 106(1): 1-16.
Geospatial Technologies for All : selected papers of the 21th AGILE conference on Geographic Information Science
- F B Mocnik
- M Raifer
Mocnik FB, Raifer M. The Effect of Tectonic Plate Motion on OpenStreetMap Data. In:
Mansourian A, Pilesjö P, Harrie L, von Lammeren R, editors. Geospatial Technologies for All
: selected papers of the 21th AGILE conference on Geographic Information Science. Cham:
Springer; 2018.