The plus-minus method for rapid field processing by portable computer of seismic refraction data in multi-layer groundwater studies

The major advantage of Hagedoorn's 'plus-minus' method of interpreting seismic refraction sections is that it is simple and quick. It is most frequently used when one shallow interface has to be investigated. But in groundwater surveys more interfaces are often present and greater depths must be reached. In such cases a practical approach is to combine the plus-minus and intercept-time methods. Modem portable computers contribute to maintaining the attractiveness of the plusminus method, allowing data processing in the field to keep pace with data acquisition. A computer program is described that not only allows progress to be monitored rapidly in the field, but also creates graphs and tables suitable for direct reporting. The program also enables long plus-minus profiles to be continuously plotted. Field examples from North Yemen are presented to illustrate the application of the program.