The 2017 KEGS Scholarship program is open and accepting applications for the 2017 scholarship award year. Applications are due April 30, 2017.
Revenue generated by the BC Geophysical Society each year from events such as the fall symposium, support the KEGS Foundation. These funds are used for the BCGS Scholarships awarded by the KEGS Foundation.
More information can be found on the poster below and on the KEGS Foundation website (www.kegsfoundation.org).
BCGS Technical Talk – April 20, 2017
Speaker : Kit Campbell, Campbell & Walker Geophysics Ltd.
Christopher (Kit) Campell’s professional life encompasses more than forty years of diverse experience in all facets of airborne and ground geophysics. Campbell & Walker Geophysics Ltd. emphasizes airborne geophysics program management and QA/QC, mapping and interpretations, forward and inversion modeling and applied geophysical research.
Title: Recent applications of airborne gravity gradiometry in mineral and petroleum applications; examples and lessons learned
Date/Time: Thursday April 20, 2017 @ 4:30pm
Location: 4th Floor Conference Room, Room 451, 409 Granville St. (UK Building at Granville and Hastings), Vancouver
Abstract:
Three examples from two recent helicopter-borne gravity gradiometry surveys are presented: the first for kimberlites in the Slave Province, the second two from a survey flown for Sedex Pb-Zn-Ag mineralization in the Kechika Trough, BC.
An innovative approach to establishing bathymetry control in a portion of the Canadian Shield is discussed.
We then move on to discuss the critical application of terrain corrections as applied in a relatively rugged survey area. Finally, again in a region of rugged terrain, we address the derivation of the tensor components using Fourier and Equivalent Source methods, and discrepancy in results.
BCGS Technical Talk – March 16, 2017
Speaker : Joel Jansen, Anglo American
Title: The HVSR passive seismic method in mineral exploration geophysics and operational geosciences
Date/Time: Thursday March 16, 2017 @ 4:30pm
Location: 4th Floor Conference Room, Room 451, 409 Granville St. (UK Building at Granville and Hastings), Vancouver
Abstract:
Near-surface passive seismic methods can be used in mineral exploration and geotechnical site-investigations to map unconsolidated regolith and thus bedrock topography to depths in excess of 100m. Passive seismic surveys measure ground motions created by ‘passive sources’ (vehicle movements, mill vibrations, etc.) rather than from ‘active sources’ (explosives or mechanical ground strikes) commonly used in conventional reflection-seismic surveying. Because the energy source is weaker, passive seismic measurements are made over tens of minutes rather than tens of seconds in the latter case. Vertical resolution, especially of thin beds, is not as good as for active-source seismic-reflection or ‑refraction surveys, but logistically, passive seismic surveys are much less costly and challenging to undertake and with almost no environmental impact.
Specifically, the Horizontal to Vertical Spectral Ratio (HVSR) method utilises the fact that the unconsolidated regolith between the free-air surface and bedrock typically acts as a waveguide for surface waves. It has been shown that vertically-polarised surface waves (i.e. Rayleigh waves) resonate in the waveguide at specific frequencies while horizontally-polarised surface waves (i.e. Love waves) do not. By taking the ratio of the vertical to horizontal power spectrums and isolating the peak frequency, the thickness (t) of the unconsolidated regolith can be determined using the simple equation:
(1)
where Vs is the shear-wave velocity of the regolith and fo is its fundamental resonant-frequency.
Knowing fo in building and bridge construction is of great importance, because if the resonant frequency of the structure matches that of the soil then there is a greater risk of collapse during an earthquake, as seen in Mexico City in 1985.
From a mineral-exploration perspective, the near-surface passive method has an obvious role to play in gravity surveying by providing a thickness-of-cover estimate beneath each station that can then be stripped from the gravity response to give a clearer picture of the true bedrock anomaly. It can also be used to corroborate depth-to-bedrock estimates from other methods, such as EM or resistivity. Where Vs is unknown, it can be estimated by making measurements in areas where the thickness of cover is otherwise known (e.g. next to boreholes).
Alternatively, in areas where the depth to the hard layer is or should be known, the method could be used to detect regions with varying Vs, as might be expected in a water-saturated zone behind a tailings dam.
This presentation expands on the background to the method and discusses several examples.
BCGS Technical Talk – February 14, 2017
Speaker : Jan Franke
Dr. Jan Francke has spent his 27-year career working solely with deep GPR systems and applications, mainly in mineral exploration. His experience spans 86 countries in every environment, ranging from Siberia to Libya. He has authored dozens of technical papers and book chapters on GPR and conducts workshops on long-range GPR worldwide.
Title: A review of ground penetrating radar applications to mineral exploration
Date/Time: Tuesday February 14, 2017 @ 4:30pm
Location: 4th Floor Conference Room, Room 451, 409 Granville St. (UK Building at Granville and Hastings), Vancouver
Abstract:
The interest in mineral exploration applications for GPR has risen significantly in recent years, due partly to extraordinary claims of performance made by some promoters. Although all radar systems are governed by the same physics, advances in electronics over the last decade have enabled much deeper penetration than was previously possible, from pocket-sized wireless systems operated by iPhones.
The talk will provide an overview of GPR’s history and principles, as well as its use in mineral exploration. A review of applications of the technology will highlight successes, with penetration to hundreds of metres in non-polar environments, as well as unexpected failures in seemingly suitable settings.
Also addressed will be recent claims of extreme penetration through any environment using “lased” EM energy or “megawatt” transmitters. These instruments and their data will be analysed within the context of accepted physics. The talk will conclude with an overview of the future of deep GPR, including advances such as real-time sampling, novel transmission modulations, instrument miniaturisation, multi-frequency systems, hybrid EM-GPR systems as well as new deployment platforms such as UAVs.
The BCGS Executive are pleased to provide details about the upcoming two-day Geophysics for Geologists short course at Roundup 2017 to be held on January 21 and 22, 2017.
Course Outline:
Day 1 (AM): Induced Polarization and Resistivity
Day 1 (PM): Gravity, Magnetics, and Radiometrics
Day 2 (AM): Electromagnetics and Magnetotellurics
Day 2 (PM): Inversion, Modelling, and Interpretation
The full course outline, list of speakers, individual coarse module summaries, and registration details can be found on the AMEBC Roundup 2017 website.
http://roundup.amebc.ca/events/geophysics-for-geologists/