Seismic microzonation in Australia

Since the 1980s seismic microzonation studies have been undertaken in Australia to assess the likely effects of earthquakes on urban centres built on unconsolidated sediments. Presently the Nakamura method is used for processing data. So far parts of Perth, Adelaide, Cairns, Gladstone, Rockhampton, Newcastle, Sydney and Launceston have been zoned. The Launceston, Tasmania, study was the pilot study for many of these as it refined the methodology used and the data obtained were incorporated into a GIS database. Building heights and site factor zoning maps were produced for the Launceston City Council. One of the major activities, of the new initiative by the Australian Geological Survey Organisation (AGSO), popularly known as the 'Cities Project', is coordinating seismic microzonation throughout Australia. Microzonation data have been included in AGSO's geohazards GIS database. This is helping local councils zone land for seismic hazards. State Emergency Services use the information to plan for emergencies resulting from the effects of earthquakes. These practical applications of seismic microzonation data will help mitigate the destructive effects of any future large earthquakes occurring near major urban centres. In the Launceston case it was found that there is a variable risk dependant on epicentral distance and the nature of relatively unconsolidated sediments in various parts of the city. Disastrous amplification could occur at some sites.