Seismic p-wave velocity in the Australian crust and upper mantle (National Geoscience Dataset)  

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

Keywords

• GIS DatasetNational

( Theme )

• seismics

( Theme )

• GIS

• AU

Australian and New Zealand Standard Research Classification (ANZSRC)

• Earth Sciences

• Published_Internal

Publication Date

2001-01-01T00:00:00

Creation Date

Security Constraints

Australian Government Security ClassificationSystem    

Classification - unclassified

Legal Constraints

Creative Commons Attribution 4.0 International Licence    

Access - restricted

Use - license

Status

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

Associations

Downloads and Links

Source Information

Source data not available.