In the present research a relationship between seismic wave velocity anisotropy and the distribution of crack orientation parameters was studied using interpretation methods based on tensor calculus. Objects of the research were limestone and sandstone deposits located within the Polish Carpathians. The relationship between velocity and azimuth of seismic profile was established. It was found that the average strike azimuth of separated vertical crack systems determined by direct fracture measurements agreed with the direction of maximum velocity. Results of the present research were compared with the results of earlier measurements earned out in carbonate rocks from the Upper Silesian Coal Basin. The existence of relationships between seismic wave velocity anisotropy and fracture parameters make it Possible to use seismic methods for determining the fracture density and the orientation of fracture systems.
Fracturing flows on the elastic properties of rock and hence on the velocity of seismic waves propagating in the rock mass. It ascertained the existence of the relationship between crack anisotropy and seismic anisotropy (Bamford & Nunn 1979, Broquet et al. 1978, Idziak 1992). The previous research were mainly made in carbonate rocks. It was established that azimuth distribution of seismic wave velocity depended on orientation and density of main crack system, This relationship was less recognized for another type of rocks and It was a reason of undertaking of the Present research.
Investigations were carried out at various quarries localized in the south of Poland. The first of studied sandstone deposits is located within the Silesian Beskidy Mts. which are a part of the Outer West Carpathians (see Fig. 1).
The "Gahura - Oblaziec" (site 3) sandstone deposit belongs to Cretaceous formations which were formed as flysh facies. It makes thin and thick bedded sandstone seric with silts intercalations. The flysh seric was very strongly deformed by tectonic processes. Underneath the flish series there are Carboniferous shales with marls. The second investigated sandstone deposit is located in a north part of the Outer West Carpathians. The Gorka - Mucharz" deposit (site 2) is built of three types of Paleocene sandstone. They belong to flysh formation which is separated as tectonic unit named the Silesian Nappe. The "Debnik" limestone deposit Site 1) is located within the Carpathian Foothills. The deposit is built of Devonian limestone and makes a part of the Debnik anticline. Underneath carbonate rock series there is a big porphyry intrusion.
Earlier measurements of seismic anisotropy were done in the north and east parts of the Upper Silesian Coal Basin (ldziak 1992). Limestone belonging to Triassic formation (the lmielin quarry - site 4) and dolomite belonging to Devonian formation (the Siewierz quarry - site 5) were studied.
The number and orientation of cracks in a rock mass are very important to consider fracturing, especially distribution and density of cracks. To give a mathematical definition for the crack geometry including all its elements, the tensor quantity called "the crack tensor" (Oda 1982, Oda 1984, Oda et al. 1986) can be employed.
