Budapest PS-InSAR dataset: Validation and interpretation

Transcription

1 Gyula Grenerczy Zoltán Oberle: Balázs Füsi Ágnes Gulyás László Vértesy György Paszera: Zsuzsa Villő Deák : FÖMI ELGI ME Budapest PS-InSAR dataset: Validation and interpretation Terrafirma H2

2 PS velocity map of Budapest and the Kőbánya anomaly Reference PS and the GPS sites are also indicated PS-InSAR reference point Kőbánya anomaly GPS reference site GPS site Velocity (mm/year) -14 to -8-8 to -4-4 to -2-2 to -1-1 to 1 1 to 2 2 to 4 4 to 8 8 to 15

3 Validation

4 GPS validation PS reference site (János kórház) Reference point of the PS-InSAR data set Velocity (mm/year) -14 to -8-8 to -4-4 to -2-2 to -1-1 to 1 1 to 2 2 to 4 4 to 8 8 to 15 The reference PS and its surroundings for stability study

5 Displacements (mm) Grenerczy et al., m= (mm/year) m= (mm/year) m= (mm/year) m= (mm/year) m= (mm/year) m= (mm/year) m= (mm/year) PSInSAR average velocity: (mm/year) Time series around the PS reference site Year The building itself, the surrounding building complexes, and the reference PS area is stable w.r.t. each other

6 GPS validation GPS reference site (BUDA) GPS site Velocity (mm/year) -14 to -8-8 to -4-4 to -2-2 to -1-1 to 1 1 to 2 2 to 4 4 to 8 8 to 15 The reference GPS site and its surroundings for validation study

7 Displacements (mm) Time series around the BUDA GPS reference site BUDA m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) PSInSAR average velocity: (mm/year) GPS data (Reference point) Year The BUDA GPS site and its surroundings is stable w.r.t. the reference PS area

8 PS-InSAR GPS validation P. Scatterer DUNA BUDA KOBA NGYT

9 GPS validation survey OGPSH (Borza, 1997) GPS network sites MGGA (Grenerczy, 2008) reference site 11 years time span 12 hour survey duration 10 elevation cut-off angle 15 sec integration time Antenna height measured with high precision leveling Equipment is dual frequency geodetic receivers/antenna

10 BUDA PS-InSAR GPS validation Sebesség (mm/év) -14 to -8-8 to -4-4 to -2-2 to -1-1 to 1 1 to 2 2 to 4 4 to 8 8 to 15

11 Kőbánya uplift and the location of the GPS site GPS site Velocity (mm/year) -14 to -8-8 to -4-4 to -2-2 to -1-1 to 1 1 to 2 2 to 4 4 to 8 8 to 15

12 KOBA Sebesség (mm/év) -14 to -8-8 to -4-4 to -2-2 to -1-1 to 1 1 to 2 2 to 4 4 to 8 8 to 15

13 Displacements (mm) Time series around the PS reference site KÕBÁNYA m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) m = (mm/year) PSInSAR average velocity: (mm/year) GPS average velocity: (mm/year) Year The motion is valid, the 0.4 mm/yr difference of the velocities is around the error levels of the two datasets (GPS site is not a reflector, there might be very small differential motion between PS and GPS site as well)

14 Investigation of tectonic origin of the anomaly

15 GPS crustal velocity map Grenerczy et al, 2005 GRL

16 The issue of tectonic origin Geodetic and sesimic strain rate of the region are both very small Bus et al., 2008 Velocity profile crossing also the anomaly shows mm/yr shortening over km Grenerczy 2001 Crustal velocities around the anomaly are less than 1 mm/yr w.r.t. stable Eurasia Grenerczy et al., 2005 Deformation rate in the region is less than 4 nstrain/yr Grenerczy and Kenyeres, 2006 Seismicity of the region is moderate with no significant activity that justifies the anomaly Tóth et al., 2006 Heat flow is normal compared to the surroundings Lenkey, 1998 The uplift of Kőbánya has no tectonic origin

17 Investigation of anthropogenic origin of the anomaly water extraction

18 Major anomalies

19 Geology and hydrogeology of the region The geological structures of the upper meters are well discovered by ground water wells and construction-geology borings. But the deeper structure is much less known, because there was no raw-material or hydrocarbon exploration in the capital of Hungary. Only one refraction seismic and a gravity survey was made in 1971 to assign the location of a thermal well in Népliget (B-88). These refraction profiles show only the surface of the high velocity contrast zone (Triassic or Eocene limestone and the Oligocene marl, clay boundary), no other detailed boundary can be seen on them. We collected and reviewed all -more than sixty- available well data with detailed geological description. Most of them are ended in the m region (Holocene - Miocene).

20 Schematic geological profile across the deep borings. The profile is crossing only the edge of the uplifting area, there is no other available monitoring data or deep boring from the closer region. The surface of the high velocity surface from the refraction seismic survey was used during the compiling of the schematic geological profile.

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22 Gelological profile A short description of the geology and hydrogeology of the area is the following: Triassic (Basement): fractured limestone and dolomite: Good water reservoir, it s on the surface in the Buda side (West from the Danube Gellért Hill). Hot springs are well known there. The first well (Kvassay B-38) on the profile is monitoring this formation: thermal karst water under pressure (positive well). It was pumping well until 1995, since then the water level hasn t changed considerably.. Eocene: fractured limestone: Similar to the Triassic, good aquifer. Oligocene: marl, clay-marl, sand: aquitard, no monitoring data. Miocene: sand, sandy clay, calcareous clay, limestone: Good aquifer; two monitoring wells (Ganz-Mávag B-63, Húsipar B-35 ) are filtering this layer. The groundwater level was dropped between 1980 and 1992, and rising from 1992 to these days. Miocene limestone is quite rare, but it is on the surface in Kőbánya Ó Hill, on the uplifting area. As we described earlier, it was an active limestone and clay mine. The limestone was excavated until the groundwater level was reached, so they didn t apply groundwater depression during the mining activity. Holocene + Pannonian: sand, sandy clay: The sandy layers are good aquifers, the Csömör B-4 monitors the Pleistocene and FÖMTERV X/4 and XIX/2 are filtering the uppermost Holocene aquifer. The Miocene aquifer is expanding on the middle of the profile. The Triassic karst water belongs to a separate water system than the Miocene aquifer. The groundwater level of the uppermost region is connected to the infiltrating water.

23 Groundwater level below surface (m) Groundwater level below surface (m) Groundwater level below surface (m) Groundwater level below surface (m) Groundwater level above surface (m) Groundwater level below surface (m) Groundwater level change between Kvassay B-38 Groundwater level change between Csömör B-4 Water level logs PSInSAR observation PSInSAR observation Groundwater level change between Húsipar B-35 Year Groundwater level change between FÖMTERV X/4 Year 0 PSInSAR observation PSInSAR observation Groundwater level change between Ganz-Mávag B-63 Year Groundwater level change between FÖMTERV XIX/2 Year -1 Well locations PSInSAR observation PSInSAR observation Grenerczy et al., Year Year

24 Conclusions The uplift of Kőbánya is verified. The motion is real and ongoing. The Kőbánya anomaly does not have tectonic origin. Regarding the anthropogenic origin, the collected hydrological data are not in disagreement with the uplift. The reason of the Kőbánya uplift is not yet fully explained by the available data sets