scholarly journals Crustal velocity and strain rate fields in the Balearic Islands based on continuous GPS time series from the XGAIB network (2010–2013)

2014 ◽  
Vol 82 ◽  
pp. 78-86 ◽  
Author(s):  
Alberto Sánchez-Alzola ◽  
Carlos Sánchez ◽  
Jordi Giménez ◽  
Pedro Alfaro ◽  
Bernadí Gelabert ◽  
...  
Keyword(s):  
Time Series ◽  
Strain Rate ◽  
Balearic Islands ◽  
Crustal Velocity ◽  
Continuous Gps ◽  
Gps Time Series

scholarly journals GPS measurements on pre-, co- and post-seismic surface deformation at first multi-parametric geophysical observatory, Ghuttu in Garhwal Himalaya, India

2020 ◽  
Vol 10 (1) ◽  
pp. 136-144
Author(s):  
P.K. Gautam ◽  
S. Rajesh ◽  
N. Kumar ◽  
C.P. Dabral
Keyword(s):  
Time Series ◽  
Surface Deformation ◽  
Translational Motion ◽  
Anomalous Behavior ◽  
Deformation Pattern ◽  
Local Earthquakes ◽  
Position Time Series ◽  
Continuous Gps ◽  
Gps Time Series ◽  
Gps Station

Abstract We investigate the surface deformation pattern of GPS station at MPGO Ghuttu (GHUT) to find out the cause of anomalous behavior in the continuous GPS time series. Seven years (2007-2013) of GPS data has been analyzed using GAMIT/GLOBK software and generated the daily position time series. The horizontal translational motion at GHUT is 43.7 ± 1 mm/yr at an angle of 41°± 3° towards NE, while for the IGS station at LHAZ, the motion is 49.4 ±1 mm/yr at 18 ± 2.5° towards NEE. The estimated velocity at GHUT station with respect to IISC is 12 ± 1 mm/yr towards SW. Besides, we have also examined anomalous changes in the time series of GHUT before, after and during the occurrences of local earthquakes by considering the empirical strain radius; such that, a possible relationship between the strain radius and the occurrences of earthquakes have been explored. We considered seven local earthquakes on the basis of Dobrovolsky strain radius condition having magnitude from 4.5 to 5.7, which occurred from 2007 to 2011. Results show irrespective of the station strain radius, pre-seismic surface deformational anomalies are observed roughly 70 to 80 days before the occurrence of a Moderate or higher magnitude events. This has been observed for the cases of those events originated from the Uttarakashi and the Chamoli seismic zones in the Garhwal and Kumaun Himalaya. Occurrences of short (< 100 days) and long (two years) inter-seismic events in the Garhwal region plausibly regulating and diffusing the regional strain accumulation.

The quality of velocities from GNSS campaign measurements when gaps in data exist

2021 ◽  
Author(s):  
Yener Turen ◽  
Dogan Ugur Sanli ◽  
Tuna Erol
Keyword(s):  
Time Series ◽  
Real Life ◽  
Velocity Estimation ◽  
Global Network ◽  
Data Gaps ◽  
East Component ◽  
Set Up ◽  
Continuous Gps ◽  
Gps Time Series ◽  
Gnss Time Series

&lt;p&gt;In this study, we investigate the effect of gaps in data on the accuracy of deformation rates produced from GNSS campaign measurements. Our motivation in investigating gaps in data is that campaign GNSS time series might not be collected regularly due to various constraints in real life conditions. We used the baseline components produced from continuous GPS time series of JPL, NASA from a global network of the IGS to generate data gaps. The solutions of the IGS continuous GNSS time series were decimated to the solutions of the campaign data sampled one measurement per each month or three measurements per year. Furthermore, the effect of antenna set-up errors, which show Gaussian distribution, in campaign measurements was taken into account following the suggestions from the literature. The number of gaps in campaign GNSS time series was incremented plus one for each different trial until only one month is left within the specific year. Eventually, we tested whether the velocities obtained from GNSS campaign series containing data gaps differ signi&amp;#64257;cantly from the velocities derived from continuous data which is taken as to be the &amp;#8220;truth&amp;#8221;. The initial efforts using the samples from a restricted amount of data reveal that the deformation rate produced from the east component is more sensitive to the gaps in data than that of the components north and vertical.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords: &lt;/strong&gt;GPS time series; GPS campaigns; Velocity estimation; Gaps in data; Deformation.&lt;/p&gt;

scholarly journals The Ground Deformation History of the Neapolitan Volcanic Area (Campi Flegrei Caldera, Somma–Vesuvius Volcano, and Ischia Island) from 20 Years of Continuous GPS Observations (2000–2019)

2021 ◽  
Vol 13 (14) ◽  
pp. 2725
Author(s):  
Prospero De Martino ◽  
Mario Dolce ◽  
Giuseppe Brandi ◽  
Giovanni Scarpato ◽  
Umberto Tammaro
Keyword(s):  
Time Series ◽  
Ground Deformation ◽  
Campi Flegrei ◽  
Volcanic Area ◽  
Campi Flegrei Caldera ◽  
Ischia Island ◽  
History Of ◽  
Continuous Gps ◽  
Gps Time Series ◽  
Gps Observations

The Neapolitan volcanic area includes three active and high-risk volcanoes: Campi Flegrei caldera, Somma–Vesuvius, and Ischia island. The Campi Flegrei volcanic area is a typical example of a resurgent caldera, characterized by intense uplift periods followed by subsidence phases (bradyseism). After about 21 years of subsidence following the 1982–1984 unrest, a new inflation period started in 2005 and, with increasing rates over time, is ongoing. The overall uplift from 2005 to December 2019 is about 65 cm. This paper provides the history of the recent Campi Flegrei caldera unrest and an overview of the ground deformation patterns of the Somma–Vesuvius and Ischia volcanoes from continuous GPS observations. In the 2000–2019 time span, the GPS time series allowed the continuous and accurate tracking of ground and seafloor deformation of the whole volcanic area. With the aim of improving the research on volcano dynamics and hazard assessment, the full dataset of the GPS time series from the Neapolitan volcanic area from January 2000 to December 2019 is presented and made available to the scientific community.

Accuracy of GNSS campaign site velocities with respect to ITRF14 solution

2020 ◽  
Author(s):  
Yener Turen ◽  
Dogan Ugur Sanli
Keyword(s):  
Time Series ◽  
White Noise ◽  
Vertical Component ◽  
Global Network ◽  
Global Studies ◽  
Time Series Analyses ◽  
Noise Error ◽  
Set Up ◽  
Continuous Gps ◽  
Gps Time Series

&lt;p&gt;In this study, we assess the accuracy of deformation rates produced from GNSS campaign measurements sampled in different frequencies. The ideal frequency of the sampling seems to be 1 measurement per month however it is usually found to be cumbersome. Alternatively the sampling was performed 3 measurements per year and time series analyses were carried out. We used the continuous GPS time series of JPL, NASA from a global network of the IGS to decimate the data down to 4 monthly synthetic GNSS campaign time series. Minimum data period was taken to be 4 years following the suggestions from the literature. Furthermore, the effect of antenna set-up errors in campaign measurements on the estimated trend was taken into account. The accuracy of deformation rates were then determined taking the site velocities from ITRF14 solution as the truth. The RMS of monthly velocities agreed pretty well with the white noise error from global studies given previously in the literature. The RMS of four monthly deformation rates for horizontal positioning were obtained to be 0.45 and 0.50 mm/yr for north and east components respectively whereas the accuracy of vertical deformation rates was found to be 1.73 mm/yr. This is slightly greater than the average level of the white noise error from a global solution previously produced, in which antenna set up errors were out of consideration. Antenna set up errors in campaign measurements modified the above error level to 0.75 and 0.70 mm/yr for the horizontal components north and east respectively whereas the accuracy of the vertical component was slightly shifted to 1.79 mm/yr.&lt;/p&gt;

2017-2019 SSE sequence and its interaction with large earthquakes in Mexico

2020 ◽  
Author(s):  
Ekaterina Kazachkina ◽  
Mathilde Radiguet ◽  
Nathalie Cotte ◽  
Jorge Jara ◽  
Andrea Walpersdorf ◽  
...  
Keyword(s):  
Time Series ◽  
Inversion Method ◽  
Stress Changes ◽  
Kinematic Inversion ◽  
Position Time Series ◽  
Seismic Moment Release ◽  
Continuous Gps ◽  
Gps Time Series ◽  
The City ◽  
Large Earthquakes

&lt;p&gt;&lt;span&gt;An intriguing sequence of a 2-stage SSE in Guerrero and a simultaneous SSE in Oaxaca took place in Mexico in 2017-2019. Three large earthquakes occur during these SSEs adding complexity to the observed surface deformations. The objective of this work is to explain the interaction between the overlapping seismic and aseismic events through the analysis of continuous GPS observations.&lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;We perform kinematic inversion of the GPS time series solving for the cumulative slip distribution on the subduction interface due to two SSEs, using Independent Component Analysis Inversion Method (ICAIM, Gualandi, 2015). The daily position time series for 2017-2019 are obtained by processing continuous data using GAMIT/GLOBK 10.7 (Herring et al, 2018). Strong postseismic signals generated by the following earthquakes 08/09/2017 Mw8.2 in Tehuantepec, 19/09/2017 Mw7.1 in Puebla-Morelos and 16/02/2018 Mw7.2 in Pinotepa are removed using the ICA decomposition. &lt;/span&gt;&lt;/p&gt; &lt;p&gt;&lt;span&gt;Our results show complex slip evolution on the subduction interface. We observe a clear change of cumulative seismic moment release rate after large seismic events of 2017 and after the earthquake in Pinotepa in 2018. The occurrence of Mw8.2 and Mw7.1 events notably slowed down the slip propagation of the Guerrero SSE. Continuous SSE in Oaxaca propagates from the northeast near the city of Oaxaca (-97.00&amp;#176;E, 16.70&amp;#176;N) towards the southwest approaching Pinotepa (-98.00&amp;#176;E, 17.00&amp;#176;N). Guerrero SSE migrates from the origin of its 1&lt;sup&gt;st&lt;/sup&gt; phase near Tecpan (-100.50&amp;#176;E, 17.50&amp;#176;N) southeastwards to Acapulco (-99.50&amp;#176;E, 17.20&amp;#176;N) where the 2&lt;sup&gt;nd&lt;/sup&gt; stage develops. Therefore the stress changes induced by the two aseismic events likely triggered the Mw7.2 Pinotepa earthquake (-98.01&amp;#176;E, 16.22&amp;#176;N). &lt;/span&gt;&lt;/p&gt;

scholarly journals Precision of continuous GPS velocities from statistical analysis of synthetic time series

2018 ◽  
Author(s):  
Christine Masson ◽  
Stephane Mazzotti ◽  
Philippe Vernant
Keyword(s):  
Time Series ◽  
Extreme Values ◽  
Regression Tree ◽  
Simple Method ◽  
Position Time Series ◽  
Gps Velocities ◽  
Synthetic Time Series ◽  
Continuous Gps ◽  
Automatic Treatment ◽  
Gps Noise

Abstract. We use statistical analyses of synthetic position time series to estimate the potential precision of GPS velocities. The synthetic series represent the standard range of noise, seasonal, and position offset characteristics, leaving aside extreme values. This analysis is combined with a new simple method for automatic offset detection that allows an automatic treatment of the massive dataset. Colored noise and the presence of offsets are the primary contributor to velocity variability. However, regression tree analyses show that the main factors controlling the velocity precision are first the duration of the series, followed by the presence of offsets and the noise (dispersion and spectral index). Our analysis allows us to propose guidelines, which can be applied to actual GPS data, that constrain the velocity accuracies (expressed as 95 % confidence limits) based on simple parameters: (1) Series durations over 8.0 years result in high velocity accuracies in the horizontal (0.2 mm yr−1) and vertical (0.5 mm yr−1); (2) Series durations of less than 4.5 years cannot be used for high-precision studies since the horizontal accuracy is insufficient (over 1.0 mm yr−1); (3) Series of intermediate durations (4.5–8.0 years) are associated with an intermediate horizontal accuracy (0.6 mm yr-1) and a poor vertical one (1.3 mm yr−1), unless they comprise no offset. Our results suggest that very long series durations (over 15–20 years) do not ensure a better accuracy compare to series of 8–10 years, due to the noise amplitude following a power-law dependency on the frequency. Thus, better characterizations of long-period GPS noise and pluri-annual environmental loads are critical to further improve GPS velocity precisions.

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