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.
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.
This article examines the performance and use of GNSS based data acquisition systems in the seasonal effects of deciduous tree foliage. As a general rule, a clear view of the sky is preferred when ...using GNSS for determining location. Season in the case of deciduous trees is the parameter affecting GNSS signal attenuation. As a result of this attenuation, positions computing weak signals tend to be less accurate. This means that using GNSS in forest is one of the most demanding uses of technology and one that requires particular attention when evaluating GNSS receivers that will be used in such an environment. This paper evaluates GNSS positional accuracy, precision and performance in the forest area. The obtained horizontal differences for three baselines in April between CORS-VRS/FKP and Total station survey results are ± (1-3) cm. The height differences obtained for three baselines in April between CORS-FKP and Total station survey results are ± (2-4) cm.
This article 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.
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