f Seismic investigations for a metro line crossing a river

In Budapest, Hungary a new metro line is plant which crosses the river Danube about 20 m below the bottom. The geology is rather complex. On the Buda side there is the dolomite structure of the Gellért hill with a height of 150 m above the Danube level. On the Pest side the dolomite can be found in the depth of about 200 m. Between them there are classical horst and graben structures under the river bottom covered by eocene and oligocene clay and marl and holocene sandy gravel. The fractures in the dolomite are in connection with the famous hot springs of Buda. Beating those fractures with the tunnel can cause the dry out of the springs.