Investigation of ground roll over loess-covered areas of Hungary

In the past, the biggest problem in land-seismic surveying was ground roll. In certain areas these surface waves made successful seismic investigation impossible, while in other areas they led to a decrease in quality, to greater or lesser extent. Understandably, studies on ground roll occupied an important role in the literature during the 1950s and 1960s (refer in particular to Dobrin 1951; Dobrin et al. 1954; Howell & Bundenstein 1955; Hagedorn 1962; White & Sengbush 1963). This situation changed drastically with the computer revolution, enabling a revision of both field and data processing techniques. The introduction of different seismic sources, geophone groups consisting of a large number of geophones, the application of a wide variety of digital frequency and twodimensional filters fitting to the local conditions, have displaced the topic of ground roll from the leading edge of seismic research. After two decades, Anstey's (1986) paper Whatever happened to ground roll? initiated a new wave of interest in the topic. Although his paper deals with the design of geophone groups as the main weapon against ground roll, most of the subsequent papers focus on 'How ground roll can be used' rather than 'How to get rid of ground roll'. From my own point of view, bearing in mind my own concern with ground roll (¡d·m 1954, 1969), different questions arose, e.g. 'Do we really know the real nature of ground roll?', or 'What possibilities do the latest computer techniques offer in the field of ground roll investigation? To study these questions, a series of experiments were carried out at ELGI thanks to the financial backing of the Hungarian Scientific Research Fund (OTKA No. T 015 5850 and 046415).