Seismic studies of local events received at three arrays in Southern Central Scotland

El-Isa, Zuhair Hasan M. (1977) Seismic studies of local events received at three arrays in Southern Central Scotland. PhD thesis, University of Glasgow.

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Printed Thesis Information: https://eleanor.lib.gla.ac.uk/record=b1628573

Abstract

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.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Subjects: Q Science > QE Geology
Colleges/Schools: College of Science and Engineering
Supervisor's Name: Powell, Dr. D.W.
Date of Award: 1977
Depositing User: Alastair Arthur
Unique ID: glathesis:1977-76757
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 09 Dec 2019 12:10
Last Modified: 09 Dec 2019 16:42
Thesis DOI: 10.5525/gla.thesis.76757
URI: http://theses.gla.ac.uk/id/eprint/76757

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