In early October 2001, the first phase of the TIGGER project commenced with the deployment of 13 broadband recorders throughout Tasmania. These recorders have been strategically positioned away from tectonic element boundaries to allow receiver function analysis methods to characterize the lithospheric structure of the major tectonic elements that comprise Tasmania. This dataset will be supplemented by broadband data from the Tasmanian Seismic Network, an array of short period and broadband recorders operated by the University of Tasmania.
In mid December 2001, four broadband recorders were deployed in southern Victoria. Surface wave data from these recorders and those in Tasmania will be utilized to image shear wavespeed variations in the lithosphere beneath southern Victoria and Tasmania, with particular focus on the Bass Strait region, which is of key importance in understanding the relationship between the geology and tectonic history of Tasmania and mainland Australia.
The final phase of the TIGGER project commenced in mid March 2002 with the deployment of 64 short period seismometers across northern Tasmania at a nominal station spacing of 15 km. Eight of the broadband sites deployed in October 2001 lie within the short period array, so the effective number of stations that are available is 72. The two principal targets of this high resolution survey are the Arthur Lineament metamorphic belt in the NW and the Tamar Fracture System in the east; both features have been mapped at the surface but their structure at depth is poorly understood. Delay-time tomography of teleseismic events will be used to image P-wavespeed variations in the crust and mantle beneath the array. All short period and broadband recorders were retrieved in mid-August 2002.
The locations of all broadband and short period stations that comprise the TIGGER experiment are shown below, along with Tasmania Seismic Network (TSN) broadband stations. TIGGER Broadband and short period stations are denoted by magenta triangles and red circles respectively; TSN broadband stations are denoted by blue diamonds. Note that eight of the TIGGER broadband stations lie within the short period array.
The station spacing within the short period array is nominally 15 km. A major challenge of the deployment was to position the stations on an approximately regular grid. Given the harsh terrain and irregular road network in northern Tasmania, the resultant station configuration is more than satisfactory.
For more information on the TIGGER project, contact