developments on the epos-ip strain rate product...machiel bos, ubi/c4g, covilhã, portugal rui...

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Developments on the EPOS-IP strain rate productAthanassios Ganas, NOA, Greece, [email protected] Kapetanidis, NOA-NKUA, GreeceFaramarz Nilfouroushan, LM, Gävle, Sweden, University of Gävle, SwedenHolger Steffen, LM, Gävle, Sweden, University of Gävle, SwedenMartin Lidberg, LM, Gävle, SwedenAline Deprez, CNRS-UGA, Grenoble, FranceAnne Socquet, CNRS-UGA, Grenoble, FranceAndrea Walpersdorf, CNRS-UGA, Grenoble, FranceAntonio Avallone, INGV, Rome, ItalyNicola D’ Agostino, INGV, Rome, ItalyJuliette Legrand, ROB, Brussels, BelgiumCarine Bruyninx, ROB, Brussels, BelgiumEduard Nastase, INCDFP RA, Bucharest, Romania,Constatin Ionescu, INCDFP RA, Bucharest, Romania,Ambrus Kenyeres, BFKH, Budapest, Hungary,Tomasz Liwosz, WUT, Warsaw, Poland, Wolfgang Soehne, BKG, Frankfurt-am-Main, GermanyMachiel Bos, UBI/C4G, Covilhã, PortugalRui Fernandes, UBI/C4G, Covilhã, Portugal

European Seismological Commission

36th General Assembly, 2-7 September 2018, Valletta - Malta

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mailto:[email protected]

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OUTLINE of PRESENTATION

1. Strain rates are of great importance for Solid Earth Sciences. Within the EUHorizon 2020 project EPOS-IP WP10 TCS-GNSS (Global Navigation SatelliteSystem - GNSS thematic core services) a series of products focused on strainrates derived from GNSS data is envisaged.

2. In this contribution, we present preliminary results from 452 permanentEuropean GNSS stations, operating until 2017 and processed at UGA-CNRS(Université Grenoble Alpes, Centre National de la Recherche Scientifique).

3. We calculated the strain-rate field using two open-source algorithmsrecommended by EPOS-IP, namely the VISR (Velocity Interpolation for StrainRate) algorithm (Shen et al., 2015) and STIB (Strain Tensor from Inversion ofBaselines), developed by Masson et al., (2014) as well as the SSPX softwaresuite (Cardozo and Allmendinger, 2009).

4. We compared the results derived from different methods and discuss thesimilarities and differences.

5. We also validated our results w.r.t literature.



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1. GNSS velocity data

EPOS Velocity data (452 permanent stations with data spanning more

than 3 years)

Processed with DD for positions operating until 2017 by UGA-CNRS,

with MIDAS (UNR) for velocities

Italy grid LON/LAT: 4.5°E<=lon<=20°E , 35°N<=lat<=48.5°N) 213 stations

Greece grid LON/LAT: 19.5°E<=lon<=29°E , 34°N<=lat<=42°N) 20 stations

Note

The first product is focused on Italy and Greece because of a) magnitude of

strain-rate w.r.t rest of Eurasia and b) availability of stations



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GNSS data (left) GNSS stations (red triangles) in Europe, (right) GNSS velocities (ITRF08 frame) in the CNRS MIDAS data

GNSS Stations Map: Italy (+Alps, Dinarides)

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(left) GNSS stations (red triangles) in Italy, (right) GNSS velocities in the CNRS MIDAS data



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GNSS Stations Map: Greece

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(left) GNSS stations (red triangles) in Greece, (right) GNSS velocities in the CNRS MIDAS data



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Model Configuration:

spatial smoothing

Min 1 km

Max 500 km

Incr. 1 km

Dist. Weight: Gaussian

Spat. Weight: Voronoi

Weight 6

Unc Thresh 0.5

Grid step 0.5°

2a. VISR result: strain-rates in Greece

Compression domains (Ionian Sea, N. Aegean Sea) are mapped satisfactorilyCompression enters into central Greece which is not justified by seismology/geologyextension in central Greece is correct in azimuth but underestimated in magnitudeEast-west switch is not well resolved

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Model Configuration:

spatial smoothing

Min. 100 km

Max. 500 km

Incr. 30 km

Dist. Weight Gaussian

Spat. Weight Voronoi

Weight 6

Unc. Thresh 0.5

Grid step 0.5°

VISR result: strain-rates in Italy

strain orientation seems correctstrain character seems correctstrain magnitude underestimated

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Model Configuration: spatial smoothing Min 100 km Max 500 km Incr 30 km Dist Weight

Gaussian Spat Weight Voronoi Unc Thresh 0.5 Grid step 0.5°

VISR result: strain-rates in Italy – influence of Wt increase

Left Wt=12, middle Wt=24, right Wt=48



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increase of Wt = smoother strain field, compression in the Po valley vanishes

2b. STIB: main processing parameters

Grid configurations

Smoothing Distance (e.g. 10km, 30km, 50km, 200km etc.)

Europe Min Max Step

Longitude -12.5 44.2 2.0

Latitude 26.7 72.6 2.0

Italy Min Max Step

Longitude 4.5 20.0 0.5

Latitude 35.0 48.5 0.5

Greece Min Max Step

Longitude 19.5 29.0 0.5

Latitude 34.0 42.0 0.5

10European Seismological Commission


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The STIB approach uses the length variations of the baselines between each pair of the geodetic stations to provide a map of the deformation over the whole area covered by the network, reducing the impact of erroneous data and noise. The computation of the strain rate tensor is obtained by inversion of the variation of the length of all the baselines obtained from the geodetic network.

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STIB result: principal strain-rate axes in Greece – grid step of 0.5°.

Left ) smoothing distance 50 km Right ) smoothing distance 100 km

Compression domains (Ionian Sea, N. Aegean Sea) are mapped satisfactorilyorientation of extension in central Greece deviated by 20-40 degreespicked up 90 degrees switch in extension along mainland Greece

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STIB result: principal strain-rate axes in Italy - grid step of 0.5°.

Left) smoothing distance 30 km Right ) smoothing distance 50 km

Extension resolved across the Apennines - compression in the Po valley, Dinaridesstrain magnitude reasonable ~50 ns/yr Apenninesno significant differences between 30-50 km smoothing distance

SSPX: main processing parameters

Grid configurations

Europe Min Max Step

Longitude -12.5 44.2 2.0

Latitude 26.7 72.6 2.0

Italy Min Max Step

Longitude 4.5 20.0 0.5

Latitude 35.0 48.5 0.5

Greece Min Max Step

Longitude 19.5 29.0 0.5

Latitude 34.0 42.0 0.5



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SSPX result: principal strain-rate axes in Greece Italy - grid step 43 km.

Comparison of VISR-SSPX results for Italy (common nodes = 733)

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Product: Dilatation_Italy (VISR original – VISR interpolated at SSPX nodes – SSPX)

GNSS stations are shown as yellow triangles



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Statistical Comparison of results for Italy (common nodes = 733)VISR parameters are Wt=12, smoothing distances 1-200km

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Diagonal lines indicate 1:1 fit



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3a. Product Validation - Greece

Chousianitis Ganas Evangelidis (2015) result: strain-rate in mainland Greece

Floyd et al. (2010) result: principal strain-rate axes in broader Aegean

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3b. Product Validation - Italy

Figure 11 D'Agostino (2014) result: principal strain-rate axes in Italy

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3b. Product Validation - Italy

1. A good match exists between the EPOS product and the Quaternary faults which are accommodating the extension in the Calabrian Arc (Calabria + NE Sicily)

2. We have also highlighted where compression is mapped.

3. This compression is the result of the Eurasia and Africa collision and it is "shared" between the SBT and the thrust fault system offshore north of Sicily.

20Principal axes of strain plotted using gmtstrainplot.sh script. Yellow circles

show EPOS GNSS sites with their codes

https://github.com/DSOlab/StrainTool .

DOI: 10.5281/zenodo.1297565

https://github.com/DSOlab/StrainTool

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4. Summary of Preliminary results

1. We presented preliminary results from 452 permanent EuropeanGNSS stations, operating until 2017 and processed at UGA-CNRS withDD technique.

2. We calculated the strain-rate field using two open-source algorithmsrecommended by EPOS-IP, namely the VISR and STIB as well as theSSPX software suite.

3. Overall, our first results reproduce the gross features of tectonicdeformation in both Italy and Greece, such as NE-SW extension acrossthe Apennines and N-S extension in Central Greece.

4. It is anticipated that the significant increase of GNSS data amountassociated with the operational phase of EPOS in the forthcomingyears will be of great value to perform an unprecedented, reliablestrain rate computation over the Eurasian plate.



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ESC2018 - S2 - 749

Thanks!

developments on the epos-ip strain rate product...machiel bos, ubi/c4g, covilhã, portugal rui...

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