Authors / CoAuthors
Collins, C.
Abstract
The dataset and accompanying animation show the seismic p-wave velocity of the crust and upper mantle in Australia through a series of slices at 1 km depth intervals from the surface down to 55 km. The velocity data is derived from velocity depth curves interpreted from seismic refraction surveys.
Product Type
dataset
eCat Id
37528
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GIS DatasetNational
- ( Theme )
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- seismics
- ( Theme )
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- GIS
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- AU
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2001-01-01T00:00:00
Creation Date
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Purpose
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
The original data are velocity-depth curves which have been modelled from seismic refraction surveys. The original models may be one-dimensional velocity-depth functions interpreted at specific locations within the surveys, usually the ends of the traverses. These usually apply to older surveys. More modern surveys achieve better spatial resolution and better control on depths and velocities along the traverses, and hence are usually modelled as two-dimensional sections. In these cases, velocity-depth curves have been derived along the traverses at strategic intervals and incorporated into the data for this animation. The velocity-depth curves were digitised at 1 km depth intervals from the surface at 0 km to 55 km. For each depth, the velocity data were gathered so as to make a two-dimensional contour image of velocities at that depth. The position (latitude, longitude) and velocity value for each of the velocity-depth curves were assembled for each of the 56 depth slices. These were then appropriately formatted and imported into Petrosys as a culture group. They were then gridded and contoured in Petrosys and displayed as a colour-filled contour map. The contour algorithm chosen was distance-weighted average with a cell dimension of 100 km. This algorithm gave the least overshoot of data in regions of poor data coverage and smoothing where the interpreted velocities have a large variation. Variations in the velocities at locations within one region may be due to azimuthal anisotropy, real local lateral velocity variation and lack of spatial resolution in older surveys. It is can also be due to the averaging effect of the refraction method, that is, the velocity depth curve represents the velocity encountered along the whole length of the ray-paths of the seismic waves used in the interpretation. Velocity contour maps were produced for each depth level and exported from Petrosys.
Parent Information
Extents
[-43.157, -9.194, 108.68, 154.967]
Reference System
Spatial Resolution
Service Information
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