ABSTRACT
Techniques for monitoring rockbursts and longwall caving in mines are similar to those used for monitoring local earthquakes with a regional seismographic network. A single case history of microseismic recording appears to predict the initial fall under massive roof conditions in an underground longwall mine.
The UCQ has monitored earthquakes around Rockhampton with a five seismograph station array. The array has an aperture of about 50 km. UCQ is able to resolve the epicentral co-ordinates to about ± 2 kilometres, with a sample rate of 100 samples per second and a time accuracy of 100 milliseconds. This resolution is achieved by using triaxial seismometers which allow better secondary phase identification of shear, converted and depth phases.
We have successfully used a single digital triaxial Kelunji seismograph to record seismic events produced from the strata failure and collapse of a longwall coal mine. Adequate resolution of location and depth requires a high sample rate (100 to 1000 Hz) and more accurate timing (about one millisecond) than required for earthquake monitoring. An appropriate stratigraphic model is also required, as is the case for earthquake location.
