Seismicity & 3-D Structure of the Eastern Goldfields
Supervisors
Research Affiliations
Degree Type/Name
Pre-requisites
Student Support
Collaboration
Prof Mike Dentith, Prof Yves Potvin
Centre for Exploration Targeting, Australian Centre for
Geomechanics
Ph.D, M.Sc or Honours - Geology, Earth Science
B.Sc in Geology (with geophysical content), Geophysics,
Mathematics, Physics; or B.Eng. in relevant subject area
The student undertaking this project is eligible for financial
support provided by the UWA Geoscience Foundation.
This project will be a collaboration with various mines in the
Kalgoorlie region.
Skills
This research project provides the opportunities for a student to obtain skills and experience
in the processing and modelling of seismic data. These skills are valued by the petroleum
industry. The mine engineering/safety component of the project provides skills sought by the
mining sector.
Project Description
Most of the mines in the Eastern Goldfields of Western Australia have their own seismic
monitoring networks, designed to detect mining induced seismicity and hence regions
susceptible to failure, rock bursts etc (Fig.1). These networks have been established by the
Australian Centre for Geomechanics (ACG). Seismic data is continuously recorded and is
available to authorised users via the Internet (Fig.2).
Figure 1
Figure 2
It is proposed to take advantage of the existing seismic networks to study the geology of the
regions surrounding the mines and also the local natural seismicity. By recording mining
blasts from adjacent mines and determining the travel times of the seismic waves over the
distance between each mine, tomographic inverse modelling can be used to establish 3D
variations in seismic velocity in the areas between the mines. Recordings from the mine
networks will be supplemented by data obtained from portable seismic recorders deployed on
the surface in the study area. Seismic velocity in the terrains where the mines are located is
primarily a function of lithology. Thus, much needed information about the geological structure
in three dimensions can be derived. These data can be integrated with other sources of
geological and geophysical data to improve sub-surface geological models of this highly
prospective terrain.
The Eastern Goldfield experiences a low but persistent level of ‘natural’ seismicity, which is
also recorded by the mine seismic networks. It has been postulated that the seismicity occurs
on major fault structures in the region. The major gold deposits in the Eastern Goldfields
occur close to these structures, which probably acted as conduits for mineralising fluids. The
hypothesis of a relationship between known faults and modern earthquakes has not been
established because to accurately locate event foci requires an adequate understanding of
seismic velocity variations in the region. Thus, the tomographically derived velocity volume
will enable natural seismicity to be accurately located, and hence its origin understood.
If the natural seismicity does occur on the known faults it adds credence to an observation
that natural seismicity acts as a trigger for mining induced seismicity. A dataset of accurately
located natural and mining induced seismic events will enable this hypothesis to be tested;
with obvious implications for mine safety.
The possible association of known faults and seismicity is also of economic significance. The
current far-field stress field is one with an east-west oriented maximum principal stress. This
is the same stress regime which is thought, based on geological studies, to have existed
when the gold mineralisation was created. Since the gold mineralising event is known to be
late in the tectonic history of the region the geometry of structures is likely to be have been
similar to that seen today. Thus, the pattern of current seismicity may contain clues regarding
the formation and location of gold mineralisation. The above is highly speculative but creates
the intriguing possibility of a unique insight into the formation of the local gold deposits from
the proposed study.
The research described above can be divided in to a series of possible student research
projects suitable for Honours, M.Sc or Ph.D studies. Moreover, depending on the particular
aspects involved it may be approached from a geological, geophysical or mining engineering
perspective. Thus, opportunities exist to participate in what would be a unique study for
students with a range of backgrounds.