ABSTRACT
Earthquakes have been felt somewhere in the Melbourne area on average every few years. The most common measure of the energy released in an earthquake is the Richter Local Magnitude Scale, and is normally used for earthquakes up to about magnitude 6. Larger earthquakes are measured on the Surface Wave Magnitude Scale. An earthquake vibration hazard map looks at seismic risk on a regional scale and it is necessary to consider local modifications due to particular characteristics of local earthquakes and the deep earth structure. The amplitude of earthquake ground motion is normally measured in millimetres and millimetres per second or millimetres per second per second. The first measurements of ground stresses to be made in the Melbourne area, were carried out in test shafts excavated during the preliminary investigations for the Melbourne Underground Rail Loop. Gibson et al. reported that earthquakes in the Melbourne area are due to compressive stresses acting in a south-east to northwest direction.
