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Nilfouroushan, Faramarz, Senior LecturerORCID iD iconorcid.org/0000-0003-1744-7004
Publications (10 of 14) Show all publications
Khorrami, F., Vernant, P., Masson, F., Nilfouroushan, F., Mousavi, Z., Nankali, H., . . . Alijanzade, M. (2019). An up-to-date block model and strain rate map of Iran using integrated campaign-mode and permanent GPS velocities. In: 27th IUGG General Assembly: G06 - Posters - Monitoring and Understanding the Dynamic Earth With Geodetic Observations. Paper presented at 27th IUGG General Assembly, 8-18 July, 2019, Montreal, Canada.
Open this publication in new window or tab >>An up-to-date block model and strain rate map of Iran using integrated campaign-mode and permanent GPS velocities
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2019 (English)In: 27th IUGG General Assembly: G06 - Posters - Monitoring and Understanding the Dynamic Earth With Geodetic Observations, 2019Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

Iran accommodates a large part of the ongoing Arabia-Eurasia collision deformation. Because of such active tectonics, the country suffers from intensive seismicity and frequent destructive earthquakes in different locations.To study further the crustal deformation in Iran, we processed the data collected during 10 years (2006-2015) from the Iranian Permanent GNSS Network and combined them with previously published velocity solutions from GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain rate map for this region and we designed a block model based on the main geological, morphological, and seismic structures. Comparison between both approaches suggests similar results and allow us to present the first comprehensive first order fault slip rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. Moreover, we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematic of the faults north of the Makran in the Jazmurian depression. Although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E-W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio, hence the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.

Keywords
GPS, deformation, Iran, strain, geodynamics
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29657 (URN)
Conference
27th IUGG General Assembly, 8-18 July, 2019, Montreal, Canada
Available from: 2019-06-04 Created: 2019-06-04 Last updated: 2019-08-08Bibliographically approved
Khorrami, F., Vernant, P., Masson, F., Nilfouroushan, F., Mousavi, Z., Nankali, H., . . . Alijanzade, M. (2019). An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities. Geophysical Journal International, 217(2), 832-843
Open this publication in new window or tab >>An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities
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2019 (English)In: Geophysical Journal International, ISSN 0956-540X, E-ISSN 1365-246X, Vol. 217, no 2, p. 832-843Article in journal (Refereed) Published
Abstract [en]

We present the most extensive and up-to-date unified GPS velocity field for Iran. We processed the data collected during 10 years (2006–2015) from the Iranian Permanent GNSS Network (IPGN) and combined them with previously published velocity solutions from GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain rate map for this region and we designed a block model based on the main geological, morphological, and seismic structures. Comparison between both approaches suggests similar results and allow us to present the first comprehensive first order fault slip rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. But we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematic of the faults north of the Makran in the Jazmurian depression. Indeed, although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E-W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio, hence the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.

Place, publisher, year, edition, pages
Oxford University Press, 2019
Keywords
GPS, Iran, Strain, deformation, Zagros, Makran
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29221 (URN)10.1093/gji/ggz045 (DOI)2-s2.0-85063728224 (Scopus ID)
Available from: 2019-02-02 Created: 2019-02-02 Last updated: 2019-08-15Bibliographically approved
Kaviani, A., Mahmoodabadi, M., Rümpker, G., Yamini-Fard, F., Tatar, M., Motavalli-Anbaran, J., . . . Nilfouroushan, F. (2019). Complex pattern of seismic anisotropy beneath the Iranian plateau and Zagros. In: : . Paper presented at European Geosciences Union (General Assembly), 7-12 April 209, Vienna, Austria. , 21, Article ID EGU2019-13815-1.
Open this publication in new window or tab >>Complex pattern of seismic anisotropy beneath the Iranian plateau and Zagros
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2019 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

We performed shear wave splitting analyses on core-refracted teleseismic shear waveforms from 150 broad-bandstations across the Iranian plateau and Zagros to investigate seismic anisotropy in the region. Seismic anisotropyis quantified by shear-wave splitting parameters, i.e. fast polarization direction and split delay time.Our measurements revealed a complex pattern of splitting parameters with variations in the trend and strength ofanisotropy across the tectonic boundaries. This complex pattern implies that a system of simple asthenosphericflow related to the absolute plate motion cannot alone explain our observations and that the lithosphere also hasa significant contribution in many parts. We compare our results to the surface deformation and velocity fieldsinferred from geodetic measurements to assess the role of the mantle in continental deformation. The rotationalpattern of the fast directions around the collision zone in Central Zagros may indicate the presence of a mantleflow around a continental keel beneath the Zagros. The agreement between the crustal and mantle deformationfield in Central Iran implies a vertically coherent deformation in this region, whereas the azimuthal variations insplitting parameters in the collision zone may suggest multi-layered anisotropy with different contributions fromthe crust and mantle.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29183 (URN)
Conference
European Geosciences Union (General Assembly), 7-12 April 209, Vienna, Austria
Available from: 2019-01-27 Created: 2019-01-27 Last updated: 2019-02-25Bibliographically approved
Nilfouroushan, F., Jivall, L., Al Munaizel, N., Lilje, C. & Kempe, C. (2019). Maintenance of the National Realisation of ETRS89 in Sweden: re-analysis of 20-years GPS data for SWEREF stations. In: : . Paper presented at European Geosciences Union (General Assembly), 7-12 April 2019, Vienna, Austria. , 21, Article ID EGU2019-7211-3.
Open this publication in new window or tab >>Maintenance of the National Realisation of ETRS89 in Sweden: re-analysis of 20-years GPS data for SWEREF stations
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2019 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The national geodetic reference frame of Sweden called SWEREF 99, was adopted in 2000 by EUREF as therealization of ETRS89 in Sweden and was officially introduced in 2001 as a national reference frame, thateventually in 2007 replaced the former reference frame. The SWEREF 99 reference frame is defined by an activeapproach through the 21 fundamental SWEPOS permanent GNSS stations, hence relying on positioning servicessuch as the network real time kinematic (NRTK) and post processing service. The SWEREF 99 coordinates areassumed to be fixed in time and no temporal variations are expected. However, the stability of the stations andtheir coordinates can be altered due to equipment change or software as well as local movements at the referencestations.To be able to check all alterations mentioned above and having a backup national network of GNSS stations,approximately 300 passive so-called consolidation stations are used. The consolidation stations are a subset (mainpart) of the so-called SWEREF stations established from 1996 and onwards. All 300 stations are remeasured withstatic GNSS for 2x24 hours using choke ring antennas on a yearly basis with 50 stations each year. The originalprocessing was done with the Bernese GNSS software (here called Bernese original) and the reprocessing wascarried out with both the Bernese and the GAMIT-GLOBK software packages during 2017-2018.The resulting coordinates in SWEREF 99 from GAMIT and Bernese processing are equal at 1.2 mm level forhorizontal and 4 mm for vertical components (1 sigma) when using the same models and processing strategy.The original processing, which partly is based on other models and parameters, differs slightly more (rms 2.4mm) for the north component. Our analysis both from Bernese and GAMIT shows that the standard uncertaintiesfor a single SWEREF 99 determination (2x24 hrs) is 2 mm for the horizontal components and 6-7 mm inheight. However, since some stations are slowly moving they have slightly increased the estimated uncertainties.It is interesting to note that the repeatability is on the same level also for the original processing, where wehave differences in models and parameters used during the years. This indicates that the SWEREF-concept ofdetermining SWEREF99 coordinates has worked well on the mentioned uncertainty level.We performed trend analysis and statistical tests to investigate the stability of the estimated SWEREF 99coordinates. The analysed station time series (minimum three observations) showed that about 14% of the stationshad significant trends at the 95%-level. The possible explanation for those trends can be either local deformationand/or residuals of uplift model and/or computational effects such as lack of good or enough close-by stations forHelmert transformations from ITRF to SWEREF 99.The outcomes of the new processing and analysis reported here, are used to analyse the stability of SWEREF99 after two decades. The results have also been used to define the SWEREF 99 component in the fit of theSWEN17_RH2000 new geoid model to SWEREF 99 and RH 2000 (Swedish realization of EVRS).

Keywords
GNSS, SWEREF, Reference frames, SWEDEN
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29182 (URN)
Conference
European Geosciences Union (General Assembly), 7-12 April 2019, Vienna, Austria
Available from: 2019-01-27 Created: 2019-01-27 Last updated: 2019-02-25Bibliographically approved
Jivall, L., Nilfouroushan, F., Al Munaizel, N., Lilje, C. & Kempe, C. (2019). Maintenance of the National Realization of ETRS89 in Sweden : re-analysis of 20 years’ GPS data for SWEREF stations. In: EUREF 2019 Symposium: Abstracts. Paper presented at EUREF 2019 Symposium, 22-24 May, 2019, Tallinn, Estonia.
Open this publication in new window or tab >>Maintenance of the National Realization of ETRS89 in Sweden : re-analysis of 20 years’ GPS data for SWEREF stations
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2019 (English)In: EUREF 2019 Symposium: Abstracts, 2019Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

The national geodetic reference frame of Sweden called SWEREF 99, was adopted in 2000 by EUREF as the realisation of ETRS89 in Sweden and was officially introduced in 2001 as a national reference frame, that eventually in 2007 replaced the former reference frame. The SWEREF 99 reference frame is defined by an active approach through the 21 fundamental SWEPOS permanent GNSS stations, hence relying on positioning services such as the network real time kinematic (NRTK) and post processing service. The SWEREF 99 coordinates are assumed to be fixed in time and no temporal variations are expected. However, the stability of the stations and their coordinates can be altered due to equipment change or software as well as local movements at the reference stations.

To be able to check all alterations mentioned above and having a backup national network of GNSS stations, approximately 300 passive so-called consolidation stations are used. The consolidation stations are a subset (main part) of the so-called SWEREF stations established from 1996 and onwards. All 300 stations are remeasured with static GNSS for 2x24 hours using choke ring antennas on a yearly basis with 50 stations each year. The original processing was done with the Bernese GNSS software (here called Bernese original) and the reprocessing was carried out with both the Bernese and the GAMIT-GLOBK software packages during 2017-2018.

The resulting coordinates in SWEREF 99 from GAMIT and Bernese processing are equal at 1.2 mm level for horizontal and 4 mm for vertical components (1 sigma) when using the same models and processing strategy. The original processing, which partly is based on other models and parameters, differs slightly more (rms 2.4mm) for the north component. Our analysis both from Bernese and GAMIT shows that the standard uncertainties for a single SWEREF 99 determination (2x24 hrs) is 2 mm for the horizontal components and 6-7 mm in height. However, since some stations are slowly moving they have slightly increased the estimated uncertainties. It is interesting to note that the repeatability is on the same level also for the original processing, where we have differences in models and parameters used during the years. This indicates that the SWEREF-concept of determining SWEREF 99 coordinates has worked well on the mentioned uncertainty level.

We performed trend analysis and statistical tests to investigate the stability of the estimated SWEREF 99 coordinates. The analysed station time series (minimum three observations) showed that about 14% of the stations had significant trends at the 95%-level. The possible explanation for those trends can be either local deformation and/or residuals of uplift model and/or computational effects such as lack of good or enough close-by stations for Helmert transformations from ITRF to SWEREF 99.

The outcomes of the new processing and analysis reported here, are used to analyse the stability of SWEREF99 after two decades. The results have also been used to define the SWEREF 99 component in the fit of theSWEN17_RH2000 new geoid model to SWEREF 99 and RH 2000 (Swedish realisation of EVRS).

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29658 (URN)
Conference
EUREF 2019 Symposium, 22-24 May, 2019, Tallinn, Estonia
Available from: 2019-06-04 Created: 2019-06-04 Last updated: 2019-08-08Bibliographically approved
Rashidi, A., Khatib, M. M., Nilfouroushan, F., Derakhshani, R., Mousavi, S. M., Kianimehr, H. & Djamour, Y. (2019). Strain rate and stress fields in the West and South Lut block, Iran: Insights from the inversion of focal mechanism and geodetic data. Tectonophysics, 766, 94-114
Open this publication in new window or tab >>Strain rate and stress fields in the West and South Lut block, Iran: Insights from the inversion of focal mechanism and geodetic data
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2019 (English)In: Tectonophysics, ISSN 0040-1951, E-ISSN 1879-3266, Vol. 766, p. 94-114Article in journal (Refereed) Published
Abstract [en]

The active tectonic deformation and hazardous earthquakes in the south and west of the Lut block have been investigated for a long time. In this study, we compute the geodetic and seismic strain rates using focal mechanism data from the Harvard CMT catalogue and various other sources including the published GPS velocities. Moreover, we also perform Focal Mechanism Stress Inversion (FMSI) to deduce a stress model for the region. Our study shows an expected correlation between the stress orientations, seismic and geodetic strain rates. Our results show that the south and west of the Lut block is generally exposed as a compressional strike-slip tectonic regime. The tectonic convergence in this area is taken up not only by motions along and across the faults but also by the rotation of those blocks which bounded by these faults. The maximum amount of rotation rate is observed where there are the main right lateral strike slip fault systems such as Sabzevaran, Gowk, Nayband, Bam, Kuhbanan, and Kahurak. The orientation of the mean stress direction, obtained from the FMSI results in the west and south of the Lut block, is approximated ~N19 E. In this area, faults are almost oblique relative to the tectonic motion direction. Moreover, there are right-lateral and left-lateral shears, in addition to the dip movements in different parts of the south and west of the Lut block. Our analyses show three main categories of the stress regimes including strike-slip faulting (43.2%), thrust faulting (38.6%), and unknown or oblique faulting (18.2%).

We also calculated seismic and geodetic moment rates for this area, which indicate the seismic moment rate is relatively high between Bam and Shahdad where there are some segments of the Gowk fault.

Keywords
Crustal deformation, Lut, Iran, strain, earthquake, seismology, tectonics
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-29800 (URN)10.1016/j.tecto.2019.05.020 (DOI)2-s2.0-85067290317 (Scopus ID)
Note

Funding:

- International Institute of Earthquake Engineering and Seismology

Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2019-08-22Bibliographically approved
Pease, V., Koyi, H. & Nilfouroushan, F. (2018). Development of the Amerasia Basin: Insights from analogue modeling. In: : . Paper presented at International Conference on Arctic Margins VIII, 11-14 June 2018, Stockholm, Sweden.
Open this publication in new window or tab >>Development of the Amerasia Basin: Insights from analogue modeling
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

The tectonic development of the Amerasia Basin and its sub‐domains (the Canada Basin, the Makarov‐Povodnikov basins, the Alpha‐Mendeleev Ridges, and the Chukchi Plateau) has long been debated.  Recent studies confirm the conjugate relationship between the Alaskan and Canadian Arctic margins, in which counterclockwise rotation of Arctic Alaska from Arctic Canada resulted in the opening of the Canada Basin; although the northward extent of this spreading is debated, the tectonic development of the Canada Basin is ‘broadly’ understood.  The precise timing and the role of the Chukchi Plateau is also problematic.  In a series of two‐plate analogue models with properties homologous of homogeneous continental crust, we were able to model the development of the Amerasia basin and its sub‐domains (those not related to the HALIP).  In all models, a triangular (ocean) basin forms between the two ‘diverging’ plates, however, depending on the mode of opening and initial plate configuration transpressive, transtensive, and ‘pure’ strike‐slip structures are generated and account for the following first order observations: i) transcurrent margins of opposite motion, ii) curvature in the fossil ridge, and ii) asymmetry of the basin.  In addition, extension and clockwise rotation of the Chukchi Plateau (without compression) is achieved as part of the upper‐plate of a detachment system in which lower‐plate motion exceeds upper‐plate motion. Our results elucidate the development of sea‐floor spreading in the Amerasia Basin and are consistent with a rotational opening scenario.

Keywords
Arctic, tectonics, physical modeling
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-26700 (URN)
Conference
International Conference on Arctic Margins VIII, 11-14 June 2018, Stockholm, Sweden
Available from: 2018-06-01 Created: 2018-06-01 Last updated: 2018-06-05Bibliographically approved
Pease, V., Koyi, H. & Nilfouroushan, F. (2018). Development of the Amerasia Basin: Where are we now?. In: : . Paper presented at 33rd Nordic Geological Winter meeting (NGWM 2018), 10-12 January 2018, Copenhagen, Denmark.
Open this publication in new window or tab >>Development of the Amerasia Basin: Where are we now?
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

This contribution reviews our current understanding of the tectonic development of the Amerasia Basin and presents new analogue modelling results relating to its formation. The Amerasia Basin is separated into the Canada Basin and the Makarov-Povodnikov basins by the Alpha-Mendeleev Ridges. Published data supports a conjugate relationship between the Alaskan and Canadian Arctic margins, in which counterclockwise rotation of Arctic Alaska from Arctic Canada resulted in the opening of the Canada Basin. Thus the tectonic development of the Canada Basin is ‘broadly’ understood, although its precise timing and the role of the Chukchi Plateau remain disputed. This leaves the Amerasia Basin and we identify two significant barriers to understanding its tectonic development: i) The northward extent of the Canada Basin fossil spreading ridge, and ii) the role of LIP magmatism. In assessing the former, we constructed a series of two-plate analogue models with properties homologous of homogeneous continental crust and simulated extension between the plates around a common rotation axis. In all models, a triangular (ocean) basin forms between the two ‘diverging’ plates, however, depending on the mode of opening and initial plate configuration transpressive, transtensive, and ‘pure’ strike-slip structures can be generated. Plates with a fixed pole of rotation that move at the same rate produce a basin that widens away from the pole along a straight ridge, whereas models with a migrating pole of rotation produce a bend in the spreading ridge and this may explain the curved ridge observed in the Canada Basin. Both models produce strike-slip faults of reversed polarity in the region opposite the pole. If the spreading ridge extended to the Lomonosov Ridge (LR), a strike-slip fault boundary is generated ± associated transtensive/transpressive features. Two plates with different spreading rates generate asymmetric basins, which is also a component of the Amerasia Basin. These results elucidate the consequences of sea-floor spreading in the Amerasia Basin and constrain opening scenarios.

Keywords
Arctic geology, tectonics, modeling
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-26627 (URN)
Conference
33rd Nordic Geological Winter meeting (NGWM 2018), 10-12 January 2018, Copenhagen, Denmark
Available from: 2018-05-26 Created: 2018-05-26 Last updated: 2018-12-06Bibliographically approved
Ganas, A., Kapetanidis, V., Nilfouroushan, F., Steffen, H., Lidberg, M., Deprez, A., . . . Kenyeres, A. (2018). Developments on the EPOS-IP pan-european strain rate product. In: D'Amico S., Galea P., Bozionelos G., Colica E., Farrugia D., Agius M.R. (Ed.), Book of Abstracts of the 36th General Assembly of the European Seismological Commission: . Paper presented at European Seismological Commission 36th General Assembly, 2-7 September 2018, Valetta, Malta. , Article ID ESC2018-S2-749.
Open this publication in new window or tab >>Developments on the EPOS-IP pan-european strain rate product
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2018 (English)In: Book of Abstracts of the 36th General Assembly of the European Seismological Commission / [ed] D'Amico S., Galea P., Bozionelos G., Colica E., Farrugia D., Agius M.R., 2018, article id ESC2018-S2-749Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Strain rates are of great importance for Solid Earth Sciences. Within the EU Horizon 2020 project EPOS-IP WP10 (Global Navigation Satellite System - GNSS thematic core services) a series of products focused on strain rates derived from GNSS data is envisaged. In this contribution, we present preliminary results from 452 permanent European GNSS stations, operating until 2017 and processed at UGA-CNRS (Université Grenoble Alpes, Centre National de la Recherche Scientifique). We calculate the strain-rate field using two open-source algorithms recommended by EPOS-IP, namely the VISR (Velocity Interpolation for Strain Rate) algorithm (Shen et al., 2015) and STIB (Strain Tensor from Inversion of Baselines), developed by Masson et al., (2014) as well as the SSPX software suite (Cardozo and Allmendinger, 2009). The vertical velocity component is ignored in this stage and other sources of deformation (GIA, hydrological, anthropogenic et al.) are not considered in the interpretation. We compare the results derived from different methods and discuss the similarities and differences. Overall, our first results reproduce the gross features of tectonic deformation in both Italy and Greece, such as NE-SW extension across the Apennines and N-S extension in Central Greece. It is anticipated that the significant increase of GNSS data amount associated with the operational phase of EPOS project in the forthcoming years will be of great value to perform an unprecedented, reliable strain rate computation over the western Eurasian plate.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:hig:diva-26481 (URN)978-88-98161-12-6 (ISBN)
Conference
European Seismological Commission 36th General Assembly, 2-7 September 2018, Valetta, Malta
Available from: 2018-04-20 Created: 2018-04-20 Last updated: 2019-01-09Bibliographically approved
Nilfouroushan, F., Jivall, L. & Al Munaizel, N. (2018). Reprocessing and analysis of 20-years SWEREF stations GPS data using BERNESE and GAMIT software. In: : . Paper presented at General Assembly of the Nordic Geodetic Commission (NKG) 2018, 3-6 September 2018, Helsinki, Finland.
Open this publication in new window or tab >>Reprocessing and analysis of 20-years SWEREF stations GPS data using BERNESE and GAMIT software
2018 (English)Conference paper, Poster (with or without abstract) (Refereed)
Abstract [en]

SWEREF 99 has been used as the national geodetic reference frame in Sweden since 2007 and is adopted by EUREF as an ETRS89 realization. It is defined by an active approach through the 21 original SWEPOS stations, hence relying on positioning services like the network RTK service and the post processing service. All alterations of equipment and software as well as movements at the reference stations will in the end affect the coordinates. For checking the effect of all alterations mentioned above and having a backup network of GNSS stations, approximately 300 nationally distributed passive so-called consolidation points are used. The main part of the consolidation points consists of so-called SWEREF points established already with the beginning in the mid-1990s. All stations are remeasured with static GNSS for 2x24 hours using choke ring antennas in a 6 years base with 50 points each year. The original processing was done with the Bernese GNSS software and the reprocessing was carried out with both the Bernese GNSS software and the GAMIT software in 2017-18 covering so far 20 years of data. The station coordinates were first estimated in ITRF2008 and then transformed to SWEREF 99 using the new land uplift model NKG2016LU and close by reference stations. The outcome will be used to analyse the stability of SWEREF 99 after two decades and has been used to define the SWEREF 99 component in the fit of the SWEN17_RH2000 geoid model to SWEREF 99 and RH 2000. Our analysis show a very good agreement between repeated measurements. The mean RMS of the SWEREF 99 coordinates which have had 3-times measurements (every ~6 years) is 2 mm for the horizontal components and 5-6 mm for height. Moreover, we did trend analysis to investigate the stability of the stations and check if any systematic trend exists in the transformed SWEREF99 coordinates. In general, no significant trend was observed. However, at some stations trends were observed due to local ground movements.

Keywords
GNSS, Reference frame, SWEPOS, GPS processing
National Category
Other Natural Sciences
Identifiers
urn:nbn:se:hig:diva-27793 (URN)
Conference
General Assembly of the Nordic Geodetic Commission (NKG) 2018, 3-6 September 2018, Helsinki, Finland
Available from: 2018-08-26 Created: 2018-08-26 Last updated: 2018-09-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1744-7004

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