Earthquakes – Friday 22 January 1988

The Australia Day holiday weekend 1988 will be remembered by the residents of Tennant Creek, NT  for a series of strong earthquakes that began on Friday the 22nd January and continued through the weekend and beyond.

The three main shocks, of surface magnitude 6.3, 6.4, and 6.8, occurred on Friday at 10.06am, 1.27pm and 9.35pm local time, and were followed by a strongly felt aftershock of magnitude 5.3 at 6.24am on Saturday morning.

The earthquakes were not the first to be felt by local residents  as two small earthquakes  followed by a swarm of over 150 events occured in January 1987, the largest four being all in the magnitude range of 5-5.5 and caused minor damage in the town. The epicentres of the January 1987 events were in the same area as the  January 1988 events, fortunately close to the Warramunga Seismic Array, about 35 kilometres south-west of the town.

Estimates of damage currently run around $1 million when loss of production at Warrego and other nearby mines is included. Remarkably there was little structural damage in the town ship.

TENNANT CREEK’s 1988 EARTHQUAKE NOW AUSTRALIA’s LARGEST AFTER GEOSCIENCE REVISES LIST

Geoscience Australia has revised the magnitudes of the country’s biggest earthquakes as part of an international project using new technology to more accurately reflect their sizes.

The earthquake recorded near Tennant Creek in the Northern Territory on January 22, 1988 is now considered Australia’s largest ever, snatching the title from Western Australia.

The magnitude 6.6 earthquake, recorded south west of Tennant Creek, was one in a series of three very large earthquakes all occurring on the same day, ranging from 6.3 to 6.6 in magnitude that shook the region and each lasting up to 45 seconds,with thousands of aftershocks being felt throughout the Northern Territory.

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Epicentre Area

Surface rupturing was evident along the two main scarps, separated by a 7 kilometre gap where no deformation occurred. The two scarps totaling 30 kilometres in length, the 22 kilometre Lake Surprise scarp with a chevron shape generally trending east-southeast, and the 8 kilometre Kunayunku scarp trending east-northeast.

 

 

The excavation of the gas pipeline near Tennant Creek to replace the earthquake damaged section. This pipeline carries natural gas from the Amadeus Basin to Darwin.

The compression buckling failure at a welded joint where the earthquake fault line intersected the gas pipeline, about 25 kilometres south-west of Tennant Creek. The 6mm thick steel wall did not rupture. This intersection of buckling and several fences provided researchers with a direct measure of the surface deformation.

 

 

 

Reference:
  • ABC News – 13 May 2016;
  • Territorystories.nt.gov.au;
  • Tennant & District Times;
  • Geoscience; 
  • BMR Research Newsletter 8 – Paul Holewa
  • The January 22, 1988 Tennant Creek Earthquakes in the Proterozoic Shield – J Roger Bowman – Paul Holewa
  • Photos and Comments – Charlie Hanna; Gavin and Joan Carpenter