Victoria's 4.8 Leongatha Quake: Why Shallow Depth Reached Melbourne

A preliminary magnitude 4.8 earthquake struck near Leongatha in Victoria at 2.01am on Saturday.

Geoscience Australia located the event near Leongatha, about 130km south-east of Melbourne, at an estimated depth of about 10km The Guardian. Tremors were felt across Melbourne's eastern suburbs. The agency received thousands of felt reports in the hours after the shock. The Bureau of Meteorology said there was no tsunami threat.

Depth helps explain the reach. At 10km, the source is shallow, so energy moves efficiently into the populated areas around Melbourne. Felt reports rose quickly. That number improves mapping of location and shaking strength. It does not change the magnitude.

The mainshock was followed 55 minutes later by a 3.1 magnitude aftershock. It followed a separate 3.3 magnitude earthquake on Thursday morning at Yarram, about 80km east of Leongatha. The Leongatha event was the second earthquake to hit regional Victoria in a week ABC.

South Gippsland is among the most active seismic zones in Australia. Saturday's quake was the largest recorded in Victoria since a 5.0 magnitude earthquake in 2023 on the Great Ocean Road. A 5.9 magnitude earthquake was recorded in 2021 near Mansfield in Victoria's north-east.

The broader context here is sequence, not size alone. Two felt events within days, plus an early aftershock, create a compact cluster for seismologists to assess — a short run of events from the same region. The focus is on fault reactivation and stress adjustment. It also tests detection limits and how fast public information moves. The practical question is how completely the smaller foreshocks and aftershocks are captured.

Looking at what this means for risk management, the exposure pattern matters more than the magnitude number. A moderate, shallow event near the edge of a large city will be felt by many people. Thousands of reports show high perceptibility. They also provide a fast dataset on shaking. Emergency managers and utilities will weigh that felt area against checks on vulnerable structures, especially older masonry, embankments and low-rise industrial buildings sensitive to short-period motion. With no tsunami threat, the hazard is limited to ground shaking and aftershocks.

Looking ahead, attention will likely stay on aftershock chances and whether the Yarram-Leongatha pairing is separate background activity in an active zone or a linked process. Either pattern fits normal variation for South Gippsland, given the Mansfield and Great Ocean Road precedents. Continued monitoring will refine locations, depths and mechanisms. Public messaging will likely stress readiness for further felt aftershocks without over-interpreting a short sequence.