In Tasmania, a significant earthquake swarm (ranging up approx 6.9 Mw) was recorded in the late 1800s with the epicentre located east of Flinders Island near the edge of the continental shelf. These earthquakes caused damage to buildings at Launceston. From this evidence alone a large future earthquake must be regarded as possible, although the low seismicity and short duration baseline of instrumental monitoring makes it very difficult to determine likelihood.

There is a further line of evidence from the geological record that indicates large earthquakes have occurred in the past and are likely to occur again. The evidence lies principally in the Lake Edgar Fault, an active fault known to have moved multiple times during the Quaternary. Investigations have shown that the fault has moved at least three times between 60 000 and 17 000 years BP (before present) and with calculated magnitudes of 6.8-7.0 MW. The effect of an earthquake from this source on a population centre such as Hobart, 80 km away, has yet to be determined and is an open question. Ground rupture from this fault would impact on the Edgar Dam built over it and have other effects on the water storage lakes. Landslides will almost certainly occur. There are also other features in Tasmania that may be active faults and there could be unknown active faults offshore, all of which could possibly be reactivated.