This study consists of processing (static-kinematic method) and analyzing data of two IGS stations that are part of the IGS network and are situated close to the epicenter of the Maule, Chile ...(February 27, 2010) earthquake. By analyzing the time series generated from daily solution two IGS stations, the displacements due to the earthquake were examined. When GNSS processing on 25–26 and February 27, 2010, especially for the Maule, Chile earthquake, are investigated, it is possible to interpret this situation as a precursor of the earthquake, as a result of the examination of the data obtained from the process of 25–26 February 2010. On 26 February 2010, the movement at the SANT, ANTC points before the earthquake was 0.18 m in the north-west direction, while it turned to the south-east direction on average 73 cm during and after the earthquake. The earthquake clearly had substantial impact on the horizontal components on February 27, 2010. The horizontal coordinates of SANT, ANTC stations have changed by around 21.5–73 cm and the height components have changes by around 2–4.2 cm based on the time series of coordinate discrepancies.
•On February 27, 2010 at 03:34 a.m. local time, a major earthquake of magnitude 8.8 struck central Chile. The earthquake nucleated in the subduction region between the oceanic Nazca plate and the continental South American plate. The epicenter of the earthquake was approximately 8 km off the Chilean coast (35.909° S, 72.733° W) and the hypocenter was located at a depth of 35 km. The fault rupture zone covered a region of approximately 100,000 square kilometers, causing major disruption and losses. The earthquake magnitude, its source and mechanism of rupture are expected. There have been over 25 major earthquakes with magnitude greater or equal 8.0 in the past 500 years.•Using relative GNSS analysis, co-seismic displacements caused by the Maule, Chile earthquake on February 27, 2010 was efficiently determined. For this reason, two IGS stations (ANTC, SANT) close to the epicenter were selected. Using the daily coordinate time series for earthquake, it was possible to compute φ and λ coordinate displacements with an accuracy of sub-cm. The horizontal displacement values were reported at the ANTC, SANT stations, which is about 35 and 145 km from the earthquake epicenter (Maule, Chile). As can be seen from the obtained data of two stations, the effect of Maule earthquake on the horizontal components was approximately 21.5–73 cm. In particular, the obtained results show that strengthen the opinion (the continuous monitoring of the Maule fault by GNSS stations) so it may be effective in predicting the earthquake.
The field of satellite navigation has seen significant advancements due to the fast development of multi-constellation Global Navigation Satellite Systems (GNSS). Around 150 satellites will be in ...service when all six systems – GPS, GLONASS, Galileo, BeiDou, QZSS, and NAVIC – are launched by 2030, offering both enormous potential and advantages for research and engineering applications. This study used an experiment on the accuracy, particularly for short, medium, long baselines (Wide Lane ambiguity solution) of the BeiDou, QZSS and QZSS/BeiDou combinations. It showed that with the integration of BeiDou/QZSS static measurements in the study region millimetre-centimetre accuracy for short, medium, and long baselines can be attained. Based on the results of this study, it can be concluded that the 1st (QZSS/BeiDou), 2nd (BeiDou), and 3rd (QZSS) strategies feature different horizontal accuracies for all categories. The obtained results with different satellite configurations for the Fixed-Wide-Lane integer ambiguity solution are compared with each other. Accuracy at the short baseline (BeiDou, QZSS, and BeiDou/QZSS satellites) was obtained in the range of 0.5–0.7 cm. For the medium baseline, it was computed around 1.8–82 cm. For the long baseline, the accuracy was 5.6–13.3 cm.
The effect of global warming on the southern polar regions necessitates careful monitoring of glacier deformations and their movements, as well as an understanding of atmospheric physics. For this ...purpose, the yearly movements of UNAVCO stations-South Pole Station (AMU2) (winter-summer) and other stations in the South Pole region have been observed in this paper for about a fifteen-year period (2006–2021). In addition, the area differences of the Antarctic continent due to seasonal changes (winter-summer) between 1980 and 2021 were investigated in this study. Moreover, the height values of the stations on the Antarctic continent were observed seasonally. The subglacial lakes in the Antarctic continent cause the differences in the height values as a result of the seasonal changes. A decrease in sea ice of 0.91 million km2 for the winter season and 0.55 million km2 for the summer season during a 41-year period has been determined for four sectors of the Antarctic continent. The temperature changes on the Antarctic continent in the summer and winter seasons (2005–2022) were also evaluated in this paper. Air temperature increases was apparent especially in the Antarctic Peninsula, East Antarctic and West Antarctic coasts. The Weddell Sea and the Amundsen Sea regions have had the most sea ice loss, each with 1.24 million km2. On the other hand, it can be observed that the East Antarctic sector has expanded by 0.32 million km2.
Applications in geodesy and engineering surveying require the determination of the heights of the vertical control points in the national and local networks using different techniques. These ...techniques can be classified as geometric, trigonometric, barometric and Global Positioning System (GPS) levelling. The aim of this study is to analyse height differences obtained from these three techniques using precise digital level and digital level, total station (trigonometric levelling) and GPS which collects phase and code observations (GPS levelling). The accuracies of these methods are analysed. The results obtained show that the precise digital levelling is more stable and reliable than the other two methods. The results of the three levelling methods agree with each other within a few millimetres. The different levelling methods are compared. Geometric levelling is usually accepted as being more accurate than the other methods. The discrepancy between geometric levelling and short range trigonometric levelling is at the level of 8 millimetres. The accuracy of the short range trigonometric levelling is due the reciprocal and simultaneous observations of the zenith angles and slope distances over relative short distances of 250 m. The difference between the ellipsoidal height differences obtained from the GPS levelling used without geoid and the orthometric height differences obtained from precise geometric levelling is 4 millimetres. The geoid model which is obtained from a fifth order polynomial fit of the project area is good enough in this study. The discrepancy between the precise geometric and GPS levelling (with geoid corrections) is 4 millimetres over 5 km.
A GNSS involves a constellation of satellites orbiting Earth, continuously transmitting signals that enable users to determine their three-dimensional (3D) position with global coverage. The ...positioning principle is based on solving an elemental geometric problem, involving the distances (ranges) of a user to a set of at least 4-5 GNSS satellites with known coordinates. These ranges and satellite coordinates are determined by the user’s receiver using signals and navigation data transmitted by the satellites; the resulting user coordinates can be computed to an accuracy of several metres. However, centimetre-level positioning can be achieved using more advanced techniques (kinematic). GPS/GLONASS technique is becoming compulsory for many applications concerning forest management and inventory. This paper aims to comparing the coordinates resulted from Post Process Kinematic with the resulted coordinates for the same points resulted from static technique. Nonetheless, it appears that forest measurements with ± 1 cm accuracy cannot be guaranteed on all occasions, since difficult situations may lead to greater errors (about ±10 cm accuracy for horizontal components and about ± (20-100) cm accuracy for vertical components).
GNSS uključuje konstelaciju satelita koji kruže oko Zemlje neprestano prenoseći signale koji omogućuju korisnicima da odrede svoj trodimenzionalni (3D) položaj s globalnom pokrivenošću. Princip pozicioniranja temelji se na rješavanju osnovnog geometrijskog problema koji uključuje udaljenost (raspon) od korisnika do niza od najmanje 4-5 GNSS satelita s poznatim koordinatama. Navedene udaljenosti i koordinate satelita određuju se pomoću korisnikovog prijamnika putem signala i navigacijskih podataka koje prenose sateliti; dobivene koordinate korisnika mogu se izračunati s odmakom od nekoliko metara. Međutim, centimetarski precizno pozicioniranje može se postići pomoću naprednijih tehnika (kinematičkih). GPS/GLONAS tehnika postaje obvezna u mnogim situacijama koje se tiču uređivanja šuma i izmjere. Cilj ovoga rada je usporedba koordinata dobivenih postprocesnom kinematikom s koordinatama za iste točke dobivene statičkom tehnikom. Usprkos tomu, čini se da se ne može jamčiti izmjera šume s preciznošću od ±1 cm u svim slučajevima, budući da zahtjevne situacije mogu uzrokovati veće greške (preciznost od oko ±10 cm za horizontalne komponente i oko ±(20-100) cm za vertikalne komponente).
GPS has become an essential tool for georeferencing. In some cases, GPS is used for unfavorable conditions although it was developed for open field studies. This paper analyzes the achievable ...accuracy and performance of GPS near the forest. Three surveying marks have been established with the distance seperation fivemeter in length. Two GPS campaigns were conducted for the selected marks in the forest. The same campaign was repeated once again after the forest was cut off. The experiments demonstrate the degradation of the GPS accuracy due to the forest. As a result, the largest horizontal accuracy errors were found to be in the forest. Horizontal accuracy errors were the smallest in the area without obstacles. Large vertical accuracy errors were produced in the forest; however vertical accuracy errors were also relatively small after the forest was cut off. The standard deviations improved by about 50–70% for both baselines and height differences when the forest was cut off. In conclusion, tree canopies greatly affected both horizontal and vertical accuracy.
One of the important indicators of developed societies, protect their history and transport them for future generations. Therefore, sustainable monitoring and determination present situations of the ...historical buildings are important for protection of them. Knowledge and awareness of these structures in terms of absolute positional and dimensional information acquisition, evaluation and analysis associated with geomatic engineering. In this context, it is aimed to monitor the existing structural deformations of barrack located in Davutpasa Campus at Yildiz Technical University, for two hundred years, using modern geodetic techniques. In this study, geodetic network, has fixed and dynamic points, established to monitor horizontal and vertical deformations occurred in the southern-east facade of barrack. Mentioned network consists of 5 reference points and 10 traverse points. Six of polygons inside of the structure and the remaining 4 polygons are out of it. The structure has 54 object points, 28 of them are based inside the structure and the remaining 26 object point of them out of it. These points are based in a form of on the wall to determine the deviations from vertical plane and also the points in a form of a pair of points are based on the wall with same vertical direction. Since the date of June 2011, the structure measured for three periods by terrestrial and satellite observation techniques. The displacements observed during three periods of measurement. Horizontal positions of 5 fixed points are measured by satellite observation techniques. Also terrestrial measurements were made depending on 5 fixed points as mentioned above to determine the 10 polygon point's horizontal position. Horizontal positions of the object points are measured by distance/angle surveying technique and calculate their coordinates with resection method depend on polygons. Vertical displacement of 15 fixed points measured by precise geometric levelling method and horizontal displacement of 54 object points measured by precise trigonometric method. In this study, design of geodetic control network, measurements, evaluation and analysis first results are given.
This paper describes an experiment carried out with the GNSS RTK method to combine GPS and GLONASS measurements in obstructed and unobstructed sites. This study investigates the RTK achievable ...accuracy and repeatability under different satellite constellations and site conditions in Samatya (coastal area), Istanbul, Turkey. The RTK (GPS and GPS/GLONASS) measurement techniques are described and compared in terms of productivity and precision. Surveyed area, control and test points as well as the impact area of trees where the precision decreases are visualised using Autodesk LandXplorer Studio ProfessionalTM Software. These obtained results indicate that integrating RTK GPS system with GLONASS is favoured for surveying applications.
Until the mid-1990s, post-processing was the only method available to determine survey- grade positions using GPS. Anew method was then introduced called Real-Time Kinematic (RTK). Real Time ...Kinematic surveying is an advanced form of relative GPS carrier phase surveying in which the base station transmits its raw measurement data to rovers, which then compute a vector baseline from the base station to the rover. RTK GPS shows a really efficient and fast improvement within today’s technological developments. The most important reason for using it is that this technique enables obtaining coordinates instantaneously and in the centimeter level accuracy. This technique is widely used in construction and survey applications because of its above mentioned properties. The aim of this paper is to evaluate the repeatability of RTK measurement accuracy under different satellite configurations near/in forest and unobstructed environments. Testing was performed by using GPS+GLONASS receivers under these conditions, i.e. tall trees forest and unobstructed areas. The obtained results of RTK testing were compared with results of total station surveying as a further quality check. Nevertheless, it appears that RTK measurements under forest environment with 1 cm accuracy cannot be guaranteed on all occasions, since difficult situations may lead to greater errors. These results indicate that integrating RTK GPS/ GLONASS system with total station is favored for surveying under forest environment.
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