The BCGS is excited to kick off the fall season with its first technical talk at this month. Hope to see you there.

SPEAKER: Dr. Ron Clowes

TITLE: High-Resolution Seismic Reflection Imaging of a Thin, Diamondiferous Kimberlite Dyke – A unique experiment

DATE: Tuesday, September 25th 2012

TIME: 4:30pm

LOCATION: Room 451, 409 Granville (UK Building at Granville and Hastings)

ABSTRACT: Seismic reflection techniques, for the first time, have imaged a thin, diamondiferous, kimberlite dyke. Standard exploration techniques for vertical kimberlite pipes fail to reveal subhorizontal or shallow-dipping intrusions whereas seismic reflection may be a suitable tool. A feasibility study and subsequent seismic survey were undertaken on the diamondiferous Snap Lake dyke (Northwest Territories, Canada). A drilling program mapped the dyke as a gently dipping sheet about 2–3 m thick. The feasibility study involved lab measurements of Vp and ρ on core samples and computer modeling to determine necessary acquisition parameters. Two 2-D lines that provide comparative datasets for different sources (explosive and vibroseis) and ground types (land and lake ice) were acquired. The explosive-source profile recorded on land yielded a superb image of the dyke from depths of 60 m to more than 1500 m over a lateral distance of 5700 m, an image that correlates well with adjacent drillhole data. On land the vibroseis source also imaged the dyke, but on ice no image was obtained due to reverberation and attenuation effects. The frequency response and unusually strong reflection amplitudes from the dyke indicate the importance of tuning effects and multiples. Finite-difference modeling confirms the variability observed on the seismic section. Apparent correlations between reflection amplitudes and dyke structure (e.g., thickness, feathering, 3-D geometry) suggest that seismic reflection data may be valuable for guiding drilling programs. Results demonstrate that high-resolution seismic methods have potential for use in kimberlite exploration, subsurface mapping and detailed imaging for mine development purposes.

SPEAKER: Boris Lum, Teck

TITLE: 1D, 2D, 3D Inversions of AEM for Applied Geophysics for Acid Rock Drainage: Red Dog Mine, Alaska

DATE: Thursday, June 7, 2012, 4:30pm

LOCATION: Room 451, 409 Granville (UK Building at Granville and Hastings)

SPEAKER: Dr. Jonathan Mwenifumbo

TITLE: Role of Borehole Geophysics in Nickel Exploration and Mining

DATE: Thursday, June 21, 2012, 4:30pm

LOCATION: Room 451, 409 Granville (UK Building at Granville and Hastings)

SPEAKER: Jeff Witter, Ph.D Geothermal Geologist / Project Geophysicist, S.J.V. Consultants Ltd.

TITLE: Volcanic Hazards and Geothermal Development

DATE: Thursday, May 24, 2012, 4:30pm

LOCATION: Room 451, 409 Granville (UK Building at Granville and Hastings)

Abstract: Volcanoes can be attractive for geothermal energy developers thanks to the high temperature resources often found beneath them. However, volcanic eruptions and their effects pose a significant hazard to geothermal development and infrastructure. Examples of volcanic phenomena which can have a negative impact on geothermal power operations include: ash fall, lava flows, pyroclastic flows, lahars and sector collapse. In general, siting of geothermal installations is critical to avoid many volcanic hazards. In some cases, though, exploiting a geothermal resource and siting infrastructure outside of volcanic hazard zones may be incompatible. A review of the literature suggests that direct impacts of volcanic eruptions on geothermal infrastructure have so far been limited. However, in the world’s top ten geothermal energy producing countries there is a clear positive correlation between the number of volcanoes with Holocene eruptions and geothermal MW capacity. Planned increases in geothermal development worldwide in the coming decades, coupled with the attractiveness of volcanically-hosted resources, suggest that volcanic hazards will become an increasing concern to developers. Fortunately, scientific researchers have recently developed a Bayesian event tree scheme to perform complete probabilistic volcanic hazard assessment for individual volcanoes. This method combines the probabilities of: an eruption, the occurrence of different types of hazardous volcanic phenomena, and the impact on specific areas that lie at specific distances from the volcano. A probabilistic volcanic hazard assessment can be quite useful to geothermal developers to help limit financial losses as it provides a quantification of the magnitude of volcanic risk for the project. These results can then be directly compared to other natural and non-natural sources of risk which can help senior management, investors, and others make informed risk decisions when working on geothermal projects in volcanic areas.