In order to arrive at a better understanding o f the seismic risk at the site o f Paks NPP multi-channel and high-resolution seismic profiling has been carried out on the river Danube. The multichannel survey offer a penetration of more than 500 m and a resolution of 1 m and 3 to 5 m at the top and the bottom of the imaged interval, respectively. In order to arrive at a joint interpretation, the special seismic profiles measured onland have been also reprocessed and they allow to arrive at the following main conclusions:
1. Seismic sections Danube-202, -203, -205, -207, -208 and Pa-2a, -2b, -3b, -12, -13, -14,-15 a n d-17 after reprocessing represent top quality data and offer the m ost credible source of information to delineate subsurface structures.
2. These sections confirm the main fault zone to the south o f the power plant passing towards ENE, and also the existence of its branch going towards NE and located in the immediate surrounding of the power plant.
3. The activity o f the young fault zone can be bracketed between the youngest Pannonian and the oldest river deposits in the area, which is the 5-0.045 Ma time interval.
However, because of the small value of the upper time limit, a most conservative approach suggests that the fault must be considered active at the present time.
4. It can be excluded, but at least it is highly improbable that the fault can create an offset of strata at or near the surface. The fault system therefore in the vicinity of Paks NPP is not capable.
Acknowledgement
The authors would like to thank Paks NPP Co. Ltd for the permission to publish these results. We thank all those colleagues who co-operated in earlier phases o f the research, first of all Laszlo Csontos and Peter Dovenyi. We are grateful for Tamas Bodoky and Geza Raner for making available the onland sections measured by ELGI. Part of the research has been supported by OTKA project No. TO 19393. We acknowledge the scientific and technical support of dr Tom M cGee (Utrecht) and Exploration Electronics Ltd. (Great Yarmouth, UK) during the Danube seismic survey. Local logistic was carried out by Geomega Ltd.
REFERENCES
Chik£n, G. ( 1992). Jelentes Paks tektonikai helyzetenek pontosi'tdsa ceijdbbl elvegzett vizsgalatok eredmdnyeirol.
5. kotet: Paks kom yekenek foldtani lefrdsa (R eport on the results o f the research carried out to constrain the tectonic situation o f Paks. V olum e V, in H ungarian), M anuscript, O rszdgos Foldtani 6s Geofizikai Adattdr, Budapest, 1-93
Horvdth, F. et al. (1990). Paks kornyezetenek szerkezeti viszonyai 6s nagytektonikai helyzete (N eotectonics o f the vicinity o f Paks, in H ungarian), Kutatdsi jelentes a M A ELG I m egbizdsdbbl, M anuscript, Budapest, 1-71
Horvdth, F. et al. (1993). Paks kornyezetenek neotektonikdja (Tectonic setting o f the vicinity o f Paks, in H ungarian), Kutatdsi jelent6s a PA Rt. megbizdsdb(51, M anuscript, Budapest, 1-92
IAEA Safety G uide 50-SG-S1 (1991). E arthquakes a n d A ssociated Topics in Relation to N uclear Pow er Plant Sititng. V ienna, 1-60
M cQ uillin, R. et al. (1984). An Introduction to Seism ic Interpretation. G raham & Trotm an Ltd., London O V E -A R U P Task 2 R eport (1996). 1-66
Rdner, G. and Szab6 Z. (1997). G eophysical explorations in the region o f Paks, in Seism ic safety o f the Paks N uclear Pow er Plant, S. M arosi and A. M esk6 eds, G RI HAS, Budapest, 6 1 -9 4
T6th, T., Horvdth, F. (1995). R eprocessing o f Shallow Seism ic Lines: Pa-14/94, Pa-3b/94, D anube-203/94 and D anube-205/94. E xclusive report for PA Rt. and O ve Arup, B udapest, 1-42
T<5th, T. et al. (1995). A kusztikus szelv6nyez.es a Dundn (A coustic profiling on the river Danube, in H ungarian) Jelent6s a PARt. resz6re, M anuscript, B udapest, 1-20
Yilm az, O. (1987). Seism ic D ata Processing. SEG Tulsa, O K , US
138
Fig. 1. B lock diagram explaining the use o f seism ic sections to understand the stratigraphic and stuctural conditions below the surface
Fig. 2. M ultichannel reflection seism ic profiling
Fig. 3. Location map. 1 = m ultichannel reflection seism ic section m easured on river Danube; 2 = high-reso- lution reflection seism ic section m easured by ELGI; 3 = reflection seism ic section m easured by ELG I; ; 4 = reflection seism ic section m easured for the oil industry; 5 = refraction section ; 6 = location o f the well
140
Fig. 4.Surveyconfiguration
E /N D /S
CLO —i (N m T t
142
Fig. 5.Danube-202interpreted time section
E N y /N W DK / SE
Fig. 6.Danube-203interpretedtime sectionE /N D /S
144
Fig.7.Danube-205interpretedtime section
Fig. 8.Danube-207interpreted time section
D N y / SW EK / N E
146
Fig. 9.Danube-208interpretedtime section
E / N
c d pFig. 10. P a-2a interpreted tim e section
ENy / NW
E / N
CDP 0
100
-200 —
300 -
400 —
ms 500 >—>
0 250 m
1_I__ I__ I__ I__ I
Fig. 12. Pa-3b interpreted tim e section
“ 200
- 3 0 0
- 4 0 0
“ 500 ms - 1 0 0
E / N D / S
200 300 400 500 600 CDP
0 M i l l I I I I I I I I I I _o
0 500 m
1--- 1--- 1--- 1___ l i
Fig. 13. Pa-12 interpreted tim e section
148
E N y / N W D K / S E
CDP 200 o _ i I
700 CDP
I I Lo
500 m
Fig. 14. P a-13 interpreted tim e section
100_ -1 0 0
200 _
300 _ _300
ms 400 _ _400 ms
E / N D / S
CDP 200 300 400 500 600 700 CDP
0_ I I I I I I I I I I I I I I I I I ! I I I L 0
- 1 0 0
— 200 ms
0^ 500 m
I i____ |__________|__________|__________|
Fig. 15. Pa-14 interpreted tim e section 100-
ms 200
-E /N D / S
CDP200 300 400 500 600 700 800 900 100011001200CDP150
Fig. 16. Fa-15interpreted time section
E / N D / S
C D P 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 C D P
0 5 0 0 m
■ ■___ i___ i___ i___ i
Fig. 17. P a -17 interpreted tim e section
152
Fig. 18.Correlationoffaults observed onseismicsections in the vicinityofthe Paks NPP. — 1 = youngfaultingobserved onseismicsections;2 = knownfaultzone confirmed bythe newseismicsections;3 = presumed branchofthe knownfaultzone;4 = alternative correlationofthe faults observed onseismic sections Danube 205-208; 5 = locationofthe well
Seism ic safety o f the P aks N uclear Pow er Plant pp. 15 3 -175.
Geomorphological investigations in the environs of the Paks NPP
M A ROSI, S an d o ran d SCH W EITZER, Ferenc
G eographical Research Institute, H ungarian Academ y o f Sciences H -1062 Budapest, AndrSssy ut 62.
1. Introduction
Geomorphological analyses and mapping to estimate the earthquake hazard in the environs o f the Paks Nuclear Power Plant are substantiated by the geomorphic evolution, its actual state and the ensemble o f landforms in a given region being a result o f a joint effect and alternation o f endogenic and exogenic processes in time and space. Recent and actual topography is a tool for reconstructing past processes and their causal relationship while trends might be useful in building scenarios for the future. Especially tectonic movements and their subsurface and surface effects might be relevant for judging about earthquake hazard.
The geomorphological and geological literature are chiefly engaged in analyses and evaluations within two m ajor topics. One of them is tracing the origin o f subsurface joints emerging through mass movements in a broader sense, such as landslides, tectonic movements and for other reasons, while the other deals with the relationship between base levels and stream channel modifications and characteristics of the contemporary drainage network orientation and valley development as a consequence of the activity o f the structural-tectonic factor.
To complement the chapters on geology and neotectonics of the present volume of studies some examples are drawn in the following when actually atectonic joints had been claimed earlier as structural ones and were used as arguments for the tectonic origin of valley orientation.