This work has been carried out to extend on the interpretation of the Upper Crustal structure under the Eskdalemuir Seismic Array and the surrounding area. A study of the dispersion of short period (about 1 sec.) surface waves from local events at different distances and azimuths was considered, but the lack of events showing such waves turned attention to the study of first P-arrivals from the same sort of events.
The thesis is in six chapters. Chapter I was given with an Introduction. In Chapter III the general aspects of the geology of the area were discussed very briefly. Previous seismic work around EKA was summarised with special reference to LOWNET and LISPB models.
Seismic array technique, its advantages and methods of array data processing were discussed in Chapter III which also included a brief description of EKA and LOWNET and a detailed description of Broughton Array which was set up temporarily during the course of this work. Chapter IV gives detailed information about the data sources, origin time recording and play-back facilities.
Preliminary results of the analysis of some EKA local events showed some systematic velocity and azimuth variations and this revealed the need for detailed information about the shallow structure under the array itself. Six shots were fired in the vicinity of EKA. Chapter V has been devoted for the presentation of the results of these shots, their discussion and interpretation. These demonstrated an anisotropy effect in the area of the array. Chapter VI presents the results of all local events, received at the three arrays, their discussion, comparison and interpretation.
A velocity structure around EKA is proposed which involves (1) a rapid increase of velocity (0.8 km/sec./km) to about 1.6 km depth followed by a slow rate (< 0.003 km/sec./km) to an undefined depth (2) a variation in the initial (zero depth) velocity with azimuth ranging from 5.0 to 4.4 km/sec. parallel and normal to the Lower Palaeozoic strike respectively. The Broughton data were consistent with this model if the Lower Palaeozoic structure under the Midland Valley is essentially flat-lying. The extent to which these conclusions are consistent with previous work is discussed.
Some of the methods of analysis are described in the Appendices (1 - 7), which also include two computer programs with their output results which form the basis for the interpretation and the above conclusions
