ASEG NSW November Meeting
Time and Date: 5:30 for 6pm start, Wednesday 16 th November 2022
Location: Club York, 99 York Street, Sydney
This year, our November technical meeting will consist of two parts:
Special Presentation: By Ken Witherly (Condor Consulting, Inc)
The Greatest Obstacle to Discovery Is Not Ignorance - It Is the Illusion of Knowledge.
Annual Student Night:
Recipients of the 2022 student scholarship will present their research:
Mackenzie Baker (UNSW) - Australia Going Under: Mantle processes and their geomorphological and biogeographical implications.
Eric Wang (USYD) - Seismic Hazard and Risk Modelling in Sydney.
Talk Overviews:
The Greatest Obstacle to Discovery Is Not Ignorance - It Is the Illusion of Knowledge
The title of this piece I term the Paradox of Discovery, has been attributed to Daniel J. Boorstin, Stephen Hawking, Henry Thomas Buckle, William H. Whyte, Anonymous and others. Like so many “quotes” available on the Internet, no one knows for sure who said it, why she or he said it, and what it really means, if it was said at all. My journey to ‘discovering’ this adage had me assembling a string of words that in a rough way, replicated the expression I found was a good encapsulation of what I was trying to express. After a relatively short time, the text as shown emerged. So for me, what does this expression convey? First, I was trying to find something which could capture how I feel about the 50 year career I have had in minerals exploration as a geophysicist. Specifically, could I convey what I feel has been the greatest obstacle to success; mostly typically the discovery of new mineral resources. To achieve this outcome, we typically rely on data which either we have caused to be gathered or is available due to the work of others. The data you generate is typically thought as being the ‘best guess’ of what is required to make the discovery for a certain deposit model which you have either accepted based on work of others or that you developed. The data you acquire is expensive compared with preexisting data and will often require time to decide what data is required, the definition and justification of budgets to pay for the work and then the impact of the time for planning, field preparation, acquisition and assessment, followed finally by the execution of a field program. Data acquired by others, while relatively inexpensive compared with ‘acquired for purpose’ data, is not likely carrying the critical information required to build a working hypothesis as to whether an unknown mineral deposit is located in the location you have deemed prospective. There is a commonly held belief in minerals exploration that when the same information is presented to different groups, the same outcome is most likely. So if previous explorers failed to locate a deposit using a given data set, other explorers are not likely to do any better. Collective industry experience suggests that the same data needs to be reviewed by five groups before a discovery is likely. This can be where the illusion of knowledge can first appear. This is a person’s or group’s belief that they possess some unique knowledge beyond the factual information available which will enable them to make better decisions that others with the same data. Can such data actually exist? Yes but its very nature can make our understanding and value of such data very difficult. Unless such knowledge is validated, the assessment process can be biased to the point that it is no longer a process whose outcomes are to be trusted. Moving past what might be called ‘dodgy data’, we can enter into the realm of ‘unknown unknown’ information. To pursue the discovery quest relying on such knowledge is inherently risky since the very nature or value of such information can be almost impossible to define.In the span of the 50 years I have pursued the discovery of new minerals deposits, the greatest gap in knowledge can only be termed ‘willful ignorance’ on the part of many of the fellow travelers in the exploration journey, those termed economic geologists who have not been able to appreciate the knowledge available to them which they chose to ignore or not take full advantage which geophysics can provide. Break this barrier down and the illusion of knowledge will be a manageable challenge and pursuing ‘unknown unknowns’ will be an enjoyable pastime.
Mackenzie Baker – Australia Going Under: Mantle processes and their geomorphological and biogeographical implications.
My project will assess the implications that tectonics, particularly dynamic uplift, intra-plate stress fields and palaeodrainage, has had on biogeography across the Australian continent. Australia has been chosen due to the intraplate setting that has made the continents tectonic activity relatively stable (Quigley et al., 2010; Sandiford, 2007). Throughout the history of Australian biogeography studies, climate has been frequently assumed as the main driver to biodiversification (Crisp et al., 2004). However, as we understand more about the connection between the mantle and the Earth’s surface, it becomes increasingly evident that alternative factors such as tectonics, must be considered in the biogeographical classification process (Ebach and Michaux, 2020). The previous narrative that climate acts as the main driver to bioregionalisation does not adequately explain the diversification of Australian species, river and drainage changes, nor does it fit into the climate schemes assumed by other continents that take on the equatorial climate approach (Ebach and Michaux, 2020). By studying the mantle and tectonic processes causing dynamic topography and other geomorphological changes, new constraints to the evolution of life on Earth can be gained. My project will examine the changes to the Australian landscape that have been brought about by tectonic and mantle processes since the Neogene (23.03Ma), including the continent-wide asymmetry of the Australian shorelines known as the ‘tilt’. As Australian traverses northward towards SE Asia, there are manifestations of geomorphological change that can be seen on the surface due to mantle processes. Previous studies of the Australian continent have determined a NNE down, SSW up, ‘tilt’ of the continent. The cause of this tilt has been determined to occur through mantle undulations causing dynamic topography. Due to this tilt, geomorphological changes have occurred on the surface, and can be seen through drainage changes, river reversals and sea level changes. As the continental surface is undergoing geomorphological change, the environments in which plant and animal species are situated upon are directly impacted by this and can be expected to alter the distributions of various species. Due to this, Australia provides an excellent canvas for studying the potential effects tectonics can have on the distributions of species across a given study area. The project will aim to determine this link through modelling the Australian continent from 40Ma to the present, using the PyBadlands software. By using PyBadlands, varying parameters of the Australian continent can be set and tested in order to reach conclusions about the relationship between tectonics and changes to the Australian landscape that may ultimately lead to changing of species distributions.
Eric Wang (USYD) - Seismic Hazard and Risk Modelling in Sydney.
My Honours project is on seismic hazard and risk modelling for Sydney. Southeast Australia receives an alarmingly large number of low magnitude earthquakes. However, the 1989 Newcastle Earthquake and 2021 Mansfield Earthquake has shown that this area, and therefore Sydney, is vulnerable to moderate magnitude earthquakes, and increasingly so with growing population density. In 2018, Geoscience Australia created the National Seismic Hazard Assessment Map (NSHA18). It successfully integrates various datasets to allow for large-scale peak ground acceleration probability analysis, and it has found that Sydney is within a region of high seismicity (also known as the SE Seismic Zone). However, there are many variables for small-scale analysis it does not consider due to the enormity of the project such as elevation and seismic site conditions (i.e. soil/geological properties). Furthermore, it does not consider risk, the human vulnerability aspect, such as fatalities, economic loss, and infrastructure. As such, the aim of this project is to create local scale hazard models for Sydney, identify areas of high hazard, and create risk models (specifically targeted at infrastructure) for those areas. I aim to use OpenQuake by the Global Earthquake Model Foundation, an open-source software (python based) that has been used to create many national probabilistic seismic hazard maps such as in Italy, Canada, and Australia. In general, OpenQuake requires three input variables for their various hazard models: fault characteristics (fault location, dip, rake, etc.), ground motion models, and site conditions. Subsequent infrastructure data can be overlayed for risk analysis. All datasets are obtained from online sources such as government websites (e.g. Geoscience Australia) or journal articles. Below is a preliminary probabilistic seismic hazard analysis map for my thesis and it is the most common for determining seismic hazard of an area. It estimates the chance of sites to exceed a certain ground motion level (usually in peak ground acceleration). This is typically described by 10% probability of exceedance in a 50- year period or 1/475 annual exceedance probability. The figure shows two major areas of high hazard in Sydney: the Botany Bay area (east) and Yarramundi area (west). Botany Bay is an area of concern due to its high population density while Yarramundi is relatively less concerning as it is sparsely populated. Therefore, future risk models will be focused on Botany Bay, followed by Yarramundi if time permits.
