The Hungarian lowland is located to the south and to west of the Carpathian mountain range and bounded to the south-east by the Transylvanian Alps. Landscape is characterized by plains, rolling hills and low mountains. The area is drained by tributaries of the Tisza River, which drains into the Danube. Climate is continental to sub-continental, with a mean annual precipitation less than 1000 mm. In the area crop out sedimentary rocks (sandstone and conglomerates), crystalline schist with limestone, and volcanic material. A Loess cover is present in the area. Due to local morphological and geological settings, mass movements of different types are common, and cause extensive damage to buildings and the infrastructure. Three landslide sites have been preliminarily singled out.
Hollóháza village is situated in a NNW-SSE direction valley in the northern part of Zemplén mountains. It is 2,5 km along the valley, but only few hundred meters wide. The foot of the valley in the village is 280-360 m, the surrounding peaks are 450-520 m high. Different thickness rhyolite tuff and sea sediments lie on the base mountain floor. These sediments dip in the direction of the valley forming a natural pervious layer. Another important factor is the mostly bentonitic rhyolite tuff, but the clays too, have high (40-50%) montmorillonite content. The recurring, swelling tuff and clay layers recline on steep volcanic rock and receive their water content through the contact surface. According to the morphological and geological situation the settlement and its close environment has high landslide hazard.
The Danube river bank of Dunaszekcso is built up of 40 m thick loess dissected by clay stripes, and below this is upper-pannonian sand. The borderline is indefinite, but is around flood level. It is soaked by high groundwater levels, as well as the waters under pressure of the upper-pannonian sand layer lifted up by movements. As a cause of this the stability of the steep slopes and rock walls gradually decreases causing surface deformations.
The Rácalmás area, similar to Dunaszekcso, is on the left bank of the Danube river and is part of the steep, high bank ridge, which can be followed down to the country border. The erosion and collapse of loess’s along the Danube, as well as the eastern shores of Lake Balaton and other hilly areas is a general problem in Hungary. In Rácalmás, on the surface a thick (50 m) of Pleistocene loess bed lays on the upper-pannonian sand and clay layers. In rainy periods or in times of high water level in the Danube these layers get saturated, which causes the development of slides. The morphology of the high banks is also an additional factor.
High instable loess river banks and former steep volcanic mountain area with several ground deformation events.
Deep seated landslides affecting urban areas and infrastructures.