Exploring the Shallow Subsurface Using Geophysics

by

Dave Bryon, Mike Cheadle, Peter Styles, Alan Mussett and Huw Davies, University of Liverpool

This courseware module explains the specific use of three applied geophysical techniques in environmental, archaeological and engineering site investigations. The objective of the module is twofold; i) To provide knowledge and understanding of the basic principles of seismic refraction, gravity surveying and electrical resistivity surveying. ii) To teach users how each of these techniques can be used either singly or in combination in site investigation. Users learn by being involved in hypothetical site investigations with particular problems. The user works through each section, initially answering questions and later 'decision making'. The module is intended for second year undergraduates and requires no more than elementary maths and physics.

Apage from the seismic refraction techniques course

The module occupies about 3Mb and is divided into four main sections - an introductory geophysics course and three projects.

A page from the Electrical Resistivity section of the Geophysical Techniques course

Users without a background in geophysical techniques are first directed to the geophysics course. This gives a brief introduction to the geophysical techniques needed to complete the projects, along with the basic physics and simple examples of their uses. The user works through the course answering a range of types of question and giving keyword answers (so prohibiting progression by simple trial and error). At the end of each course section the main points are displayed in a summary sheet.

Students take charge of a hypothetic company carrying out site investigates. Projects 1-3 are accessed from the "CompanyHQ" page.

When the course is completed the user chooses one of the three projects. Each poses a different problem in site investigation. The projects are: 1) Location of a lost air-raid shelter; 2) Siting of a dam across a river valley; 3) Investigation of an archaeological site. For each problem the user is presented with relevant geophysical data sets and is asked to select an appropriate technique(s), design a strategy for solving the problem and then interpret the data. Interpretation is amplified by further explanatory sections which may be accessed by 'hot screen areas'. These sections require interactive learning by the user and each contains a 'library' of information into which the user can probe in order to correctly answer the questions posed. At each stage, the user gains results (which may or may not be correct or conclusive) which they use to decide what to do next.

Maps of the project site can be accessed at any time whilst working through a project

At the end of each project the student is given a summary evaluating his/her progress through the project

At any time whilst working through a project, the user may access maps and general information on that project as well as a brief summary of geophysical techniques. An 'Equations Database' listing the relevant formulae used in the calculations may also be accessed at any time.

Running the software

The different parts of the module are accessed via a main menu and navigation around the module is by means of buttons along the base of the screen.