Seismic experts expect Adelaide to be hit by large earthquakes in the future

It has been 67 years since Adelaide was hit by a large earthquake. Experts warn it is only a matter of time before it happens again.

Adelaide should brace itself for large earthquakes in the future, as experts forecast seismic events of a magnitude of 6.5 on the Richter scale.

The city straddles several fault lines which constantly are shifting beneath the surface, creating three to four small tremors each day which are never felt.

Instead, they are being measured by geoscientists monitoring the seismic activity to estimate when a big earthquake might hit.

Public interest in earthquakes within South Australia has risen in recent weeks with shockwaves from two large quakes in Victoria being felt across the South East and metropolitan Adelaide.

The most recent was early last Saturday, when a shallow earthquake measuring 4.8 on the Richter scale was recorded at Murrayville, near the SA-Victoria border.

This followed a 6.0 earthquake near Mansfield, north of Melbourne, late last month which caused minor damage in Melbourne suburbs.

March 2 1954 Front Page of The Advertiser on March 2, 1954.

Tearsheet from Adelaide newspaper "The News" dated March 1 1954.

A worker examines the damage to a building in Chapel Street in Melbourne after a 5.9 magnitude earthquake. Picture: William West/AFP

Geoscience Australia senior seismologist Dr Trevor Allen said the Mt Lofty and Flinders Ranges were among the most seismically active regions of Australia.

Dr Allen said Adelaide had the greatest exposure to “neotectonic faults” of all Australian capital cities, with more than a dozen known fault lines within 50km of the city.

“Every year, about 15 earthquakes of magnitude 2.5 and larger occur in the region from Hawker in the north to Victor Harbor in the south,” he said.

“The city of Adelaide is bounded by several neotectonic features, that is faults, that we think have moved during large earthquakes over the recent geological period.”

Dr Allen said there were four main fault lines near Adelaide – Para, Eden-Burnside, Clarendon-Ochre Cove and Willunga.

A map showing the fault lines which run through Adelaide and surrounding areas.

“These faults range up to almost 100km in length, with cumulative vertical movements estimated to be up to 200m from one side of a fault to the other in some cases,” he said.

“Current knowledge suggests that a large earthquake, up to or exceeding magnitude 6.5 on one of these faults, might occur somewhere between every 5000 to 10,000 years.”

The last time Adelaide was struck by a major earthquake was 1954, when a 5.4 tremor with an epicentre at Darlington, 14km south of the CBD, caused widespread damage.

There were more than 30,000 insurance claims for a total amount equivalent to $280m from the event.

The quake was believed to have originated within the Eden-Burnside fault line, at a depth of 4km.

A shop in the Adelaide CBD was damaged in the 1954 earthquake which hit the city.

An Adelaide shopkeeper cleans up bottles broken in the 1954 earthquake.

An Adelaide woman inspects damage to her home caused by the earthquake.

The southern suburbs sustained the worst damage, with fallen chimneys and damage to brick and masonry structures while St Francis Xavier Cathedral and the General Post Office clock tower in the city and a newly completed hospital at Blackwood also were damaged.

Similar-sized earthquakes had been experienced at Warooka, on Yorke Peninsula, in 1902 and Beachport, in the South East, in 1897.

An Adelaide man cleans up his house following the 1954 earthquake

Dr Allen said if earthquakes of the same intensity occurred again, there would be substantial damage across Adelaide, which had grown significantly since the 1954 quake.

“They would greatly impact many people in the greater Adelaide region,” he said.

“Consequently, we must ensure future urban development and infrastructure considers potentially large earthquakes in its design and construction using modern building codes and standards.”

Dr Allen said geoscientists were working to determine the risk of large earthquakes in the metropolitan Adelaide area.

“Future investigations between Geoscience Australia and the University of Melbourne on the Willunga fault intend to explore and address some of these uncertainties,” he said.