|
| |
|
|
Aplikace Galileo High Accuray Service
Kazmierski, Kamil ; Hadas, Tomasz ; Kudłacik, Iwona ; Marut, Grzegorz ; Madraszek, Szymon
Since January 2023 the Galileo High Accuracy Service (HAS) is available to registered users. Within the HAS users can retrieve clock and orbit corrections, as well as code biases for Galileo and GPS constellations. Galileo HAS covers almost the entire globe and is the next system, after the Japanese CLAS (Japanese Centimeter Level Augmentation Service) and the Chinese PPP-B2b, that provides corrections via a satellite signal. These Galileo corrections are transmitted in the Galileo E6 signal but also via the Internet stream. The official HAS Service Definition Document indicates that the positioning accuracy is better than 25 cm and better than 30 cm for horizontal and vertical components, respectively. HAS corrections can be used in difference real-time applications without Internet connection. The presented work shows the use of Galileo HAS corrections in various geoscience applications such as positioning, timing, troposphere monitoring or coseismic vibrations detection. Additionally, the quality of the transmitted HAS correction is also verified using the SISRE parameter. The computations are carried out in the in-house developed GNSS-WARP software with the Internet HAS corrections saved in the ASCII files by the BKG Ntrip Client software. The Galileo HAS corrections quality using SISRE parameter equal to 8.6 cm and 13.0 cm for GPS and Galileo respectively. The experiment with Precise Point Positioning reveal sub-decimeter and centimeters accuracy in kinematic and static approach, respectively. In terms of timing precision Galileo HAS ensure precision of single nanosecond. Zenith Tropospheric Delay estimation with the use of evaluated corrections meet the requirement of troposphere monitoring and coseismic vibrations detection was also possible.
|
|
|
Moment-tensor inversion of earthquakes in Greece, method ISOLA
Křížová, Dana
3 Title: Moment-tensor inversion of earthquakes in Greece, method ISOLA Author: Dana Červinková Department: Department of Geophysics Supervisor: Prof. RNDr. Jiří Zahradník, DrSc. Supervisor's e-mail address: jz@karel.troja.mff.cuni.cz Abstract: The possibility of obtaining a reliable moment tensor using a low-frequency waveform inversion from a single seismic station is studied. Deviatoric part of the moment tensor is described in usual way, using its orientation (angles strike, dip, rake), scalar seismic moment M0 and the double-couple percentage (DC%), and also by means of the coefficients of linear combination of elementary mechanisms. We estimate the formal error of the coefficients and study conditionality of the inverse problem. Data from earthquakes Trichonis (Mw = 5.2, April 2007) and Leonidio (Mw = 6.2, January 2008), Greece, are processed using software ISOLA (Sokos and Zahradník). The moment tensor is calculated from many stations and its stability is tested. This reference solution is compared to those independently obtained from single stations. Synthetic tests are performed to understand why the single-station estimates are sufficient for Trichonis, but not for Leonidio, paying attention to the focal depth, station azimuth and epicentral distance. It is found that the depth is crucial at...
|
|
|
Development of effective code for earthquake dynamic source simulations
Premus, Jan ; Gallovič, František (advisor) ; Zahradník, Jiří (referee)
Title: Development of effective code for earthquake dynamic source simulations Author: Bc. Jan Premus Department: Department of Geophysics Supervisor: doc. RNDr. František Gallovič, Ph.D, Department of Geophysics Abstract: Dynamic rupture modeling coupled with strong motion data fitting offers an insight into physical mechanisms behind earthquake sources [Gallovic et al., 2019]. Running a large number of dynamic model simulations is required due to the nonlinearity of the inverse problem. The goal of this Thesis is a development of an efficient forward solver for the dynamic inversions. The fi- nite difference staggered grid code FD3D by Madariaga and Olsen [1998] served as a basis for the development, offering sufficient speed, but rather low accu- racy. Traction at split node implementation of the fault boundary condition and perfectly matched layers as the absorbing boundary condition were required to obtain desirable accuracy. In addition to the slip weakening friction law, fast ve- locity weakening friction law has been implemented, increasing the applicability of the code. We test the new code FD3D TSN using USGS/SCEC benchmarks TPV5 (slip-weakening friction) and TPV104 (fast rate weakening friction) [Harris et al., 2018], showing very good agreement with results calculated by advanced numerical...
|
|
|
Relative earthquake locations
Jeschkeová, Zuzana ; Bachura, Martin (advisor) ; Doubravová, Jana (referee)
This bachelor thesis concerns the issues related to techniques of earthquake locations. The methods can be divided into a two groups: absolute (Geiger method, grid search) and relative (master-event, hypoDD) ones. A greater emphasis is put on the latter ones - the relative methods. In these methods make use of so-called differential times - absolute time differences between phase arrivals of two earthquakes. The differential times can be estimated by the means of waveform cross-correlations. Our main objective was to compare cross-correlated differential times with the real ones and determine their accuracy. The analysis revealed that the difference - bias in differential time is present and for tho earthquakes with different magnitude it can reach 0.06 s. Keywords: locations, earthquakes, cross-correlation, seismograms
|
|
|
Earth as a dynamic body
Dlask, Martin ; Čížková, Hana (advisor) ; Drozd, Zdeněk (referee)
The aim of this bachelor thesis is to serve as explanatory instrument for teachers and their students during geography and physics classes on gymnasiums. The main goal of this thesis is to extend the knowledge of physics the Earth. This thesis is primaryly focused on introducing the Earth as dynamic body.I explain, that energy released during cooling of the Earth is responsible for plate tectonics, volcanic and seismic activity, and internal magnetic field. Powered by TCPDF (www.tcpdf.org)
|
|
|
Studium elektromagnetických emisí pozorovaných družicí DEMETER
Píša, David ; Santolík, Ondřej (advisor) ; Shklyar, David R. (referee) ; Souček, Jan (referee)
David PÍŠA Study of electromagnetic emissions recorded by the DEMETER satellite Abstract : This thesis presents results based on wave measurements performed by the DEMETER space- craft. This French spacecraft was operating between 2004 and 2010 at the altitude of ∼660 km. We focus on measurements of the electromagnetic waves and plasma density in the vicinity of imminent earthquakes. In the first part, we present a study of plasma density variations in the vicinity of a very powerful earthquake in Chile (Mw 8.8) which occurred on February 27, 2010. Data recorded before the main shock along orbits close to the future epicenter showed increasing plasma den- sities. A statistical analysis using 4 years of data to monitor density variations under similar conditions has been performed. This study shows that a large increase of the plasma density is very uncommon at this location. In the second part, a statistical study (∼6.5 years) of variations of VLF wave intensity is shown. We have analyzed all available data measured close (in time and space) to large earth- quakes (M≥5). Data related to more than 12000 earthquakes have been compared with an unperturbed background distribution. We confirm the previously reported results of a statis- tically significant decrease of the wave intensity at frequencies of about...
|
|
|
Moment-tensor inversion of earthquakes in Greece, method ISOLA
Křížová, Dana
3 Title: Moment-tensor inversion of earthquakes in Greece, method ISOLA Author: Dana Červinková Department: Department of Geophysics Supervisor: Prof. RNDr. Jiří Zahradník, DrSc. Supervisor's e-mail address: jz@karel.troja.mff.cuni.cz Abstract: The possibility of obtaining a reliable moment tensor using a low-frequency waveform inversion from a single seismic station is studied. Deviatoric part of the moment tensor is described in usual way, using its orientation (angles strike, dip, rake), scalar seismic moment M0 and the double-couple percentage (DC%), and also by means of the coefficients of linear combination of elementary mechanisms. We estimate the formal error of the coefficients and study conditionality of the inverse problem. Data from earthquakes Trichonis (Mw = 5.2, April 2007) and Leonidio (Mw = 6.2, January 2008), Greece, are processed using software ISOLA (Sokos and Zahradník). The moment tensor is calculated from many stations and its stability is tested. This reference solution is compared to those independently obtained from single stations. Synthetic tests are performed to understand why the single-station estimates are sufficient for Trichonis, but not for Leonidio, paying attention to the focal depth, station azimuth and epicentral distance. It is found that the depth is crucial at...
|
|
|
Moment-tensor inversion of earthquakes in Greece, method ISOLA
Červinková, Dana ; Šílený, Jan (referee) ; Zahradník, Jiří (advisor)
3 Title: Moment-tensor inversion of earthquakes in Greece, method ISOLA Author: Dana Červinková Department: Department of Geophysics Supervisor: Prof. RNDr. Jiří Zahradník, DrSc. Supervisor's e-mail address: jz@karel.troja.mff.cuni.cz Abstract: The possibility of obtaining a reliable moment tensor using a low-frequency waveform inversion from a single seismic station is studied. Deviatoric part of the moment tensor is described in usual way, using its orientation (angles strike, dip, rake), scalar seismic moment M0 and the double-couple percentage (DC%), and also by means of the coefficients of linear combination of elementary mechanisms. We estimate the formal error of the coefficients and study conditionality of the inverse problem. Data from earthquakes Trichonis (Mw = 5.2, April 2007) and Leonidio (Mw = 6.2, January 2008), Greece, are processed using software ISOLA (Sokos and Zahradník). The moment tensor is calculated from many stations and its stability is tested. This reference solution is compared to those independently obtained from single stations. Synthetic tests are performed to understand why the single-station estimates are sufficient for Trichonis, but not for Leonidio, paying attention to the focal depth, station azimuth and epicentral distance. It is found that the depth is crucial at...
|
guest ::
