Tuesday, 25 March 2014

Fracking qualifies for aged pension

Over on the About Geology Blog, Andrew Alden shows us that yesterday was the 65th anniversary of Hydraulic Fracturing (Fracking/Fraccing). I was quite surprised to learn that this “unconventional” technique was developed in my grandparent’s generation. In his blog post Andrew points out some of the controversies in the United States about “Fracking” and provides his opinion on the practice. I don’t want provide to provide any opinion here about the Australian situation, just to outline a very quick summary of how it is used.

Having said the above, I think it is important to mention that there is some differences in experience between Australia and the United States. The main difference being that any chemicals used in “Fracking” must be fully disclosed (unlike the USA where they are much more secretive). Another difference is that in the USA “Fracking” is most commonly used in “Shale Gas” formations where it has been reportedly been linked to many problems with regard to aquifer cross-connection and contamination. Coal Seam Gas in the USA are also a situation where Fracking is frequently used, though this has very few of the same issues of Shale Gas fracking (Blackam 2014).

In Australia “Fracking” is frequently used in “Tight Gas” situations where directional drilling alone is impractical. This practice is especially common in the Moomba Gas Fields of Queensland and South Australia now this field has become depleted in the easily accessible “Conventional” gas. Hydraulic fracturing is also sometimes used in Coal Seam Gas situations. In the Northern Rivers I understand there has only been one case of hydraulic fracturing which was used in a “tight” situation.

This is by no-means a clear bill of health for unrestricted use of the practice of Fracking. Many questions still remain about what damage the practice can cause (e.g. Batley & Kookana 2012).

I’ve done some posts on the different natural gas sources and summarised them on this page. Until I actually do a blog post on what hydraulic fracturing actually is, I recommend this summary from the CSIRO. Alternatively, this CSIRO/Industry publication, though developed in partnership with the gas industry is actually even more detailed and very good.


*Batley, G.E. & Kookana, R.S. 2012. Environmental issues associated with coal seam gas recovery: managing the fracking boom. Environmental Chemistry. vol9 p425-428
*Blackam, M. 2014. Source, Fate and Water-Energy Intensity in the Coal Seam Gas and Shale Gas Sector: An Exploration of the relationship between energy and water in the unconventional gas sector. Water, Journal of the Australian Water Association. vol41 No.1 p51-56

Friday, 14 March 2014

Armidale submerged

Armidale is well known for its height above sea level, with some areas above 1000m it is at a relatively high altitude by Australian standards. The city is located in the New England, ‘Northern Tablelands’ which provides an indication of the landscape in which it is situated. The area resembles a very large plateau with comparatively light rolling hills compared with the nearby escarpment and edges of the tablelands. In fact, Armidale is just a tiny bit to the east of the crest of the Great Dividing Range. Surprisingly, this area was in part inundated by a lake, or lakes.

Examples of some rocks that make up the Armidale beds
The big sample at the front has been partially turned into silcrete.
One of the headwaters of the Macleay River, Dumaresq Creek flows through Armidale. In places this creek, as well as other creeks in the area, have cut through the basalt rock that covered the area. A description of this process was covered in an earlier post. In this post I’d like to describe the sediments that lie under the basalt. These are Eocene (or earlier) sediments named by Voisey (1942) the Armidale Series, now known as the Armidale beds.

The Armidale beds are comprised of fluvial (river) and lacustrine (lake) deposited sediments. These are principally conglomerates, siltstones, sandstones and shale. Interestingly, the shales are laminated possibly as a result of seasonal deposition in a lake. They also contain abundant plant fossils. The material that makes up the sediments is particularly obvious in the conglomerate. The conglomerate clasts are derived from the older underlying geology, for example clasts of jasper, quartzite and granites.

The Armidale beds occur in small remnant areas (the balance of the beds having been eroded away). These remnants occur throughout the Armidale area but almost as far away as Wollomombi to the west, near Dangars Falls to the south-east and Kellys Plains to the south-west. Voisey 1942 named this area Armidale Lake which is a palaeo-lake that only exists now in the sediments that it left. The formation of Armidale Lake occurred either before or during the volcanism that ended up covering a majority of the Armidale region in blankets of basalt lava (lavas of the Central Volcanic Province). In fact, the Armidale beds were preserved by this blanket of basalt both directly and through metamorphism beds in the area of contact. This metamorphism of the Armidale beds created a layer of hard silcrete (once known as greybilly) which itself was resistant to erosion and helped preserve the underlying un-silcretized sediment from being washed away.

The picture above is an example of the Armidale Beds that occur near the Armidale garbage disposal centre. A very accessible example is located on Madgwick Drive on the way to the University. It is actually one of the best remaining exposures of the unit and has been used for years by local schools and the university. Indeed, Banaghan & Packham 2000 have the road cutting as a stop on their Armidale-Yarowych geological tour.


*Branagan,, D.F. & Packham, G.H. 2000. Field Geology of New South Wales. Department of Mineral Resources.
*Fitzpatrick, K.R. 1979 The Armidale area. Geological Survey of New South Wales. Geological Excursion Handbook 1
*Voisey, A.H. 1938. The Geology of the Armidale District. Proceedings of the Linnean Society of New South Wales.
*Voisey, A.H. 1942. The Geology of the County of Sandon, NSW. Proceedings of the Linnean Society of New South Wales. V67.

Saturday, 1 March 2014

An Australian and Indonesian Geological Relationship

Australia got its most recent reminder about the power of volcanoes only a couple of weeks ago. Mount Kelud (or Kelut) erupted on the populous island of Java in the Indonesian Archipelago. The resulting ash cloud has caused immense problems for people travelling to Asia or even Europe. The Darwin Volcanic Ash Advisory Centre (Darwin VAAC) advised that aircraft travelling on many of the popular Indonesian (particularly Bali), South and East Asian routes, would be in great danger of having engines failing. Therefore many flights were grounded.

The Darwin VAAC is responsible for Volcanic Ash advice covering the Indian sub-continent and South East Asia (The most concentrated number of active volcanoes in the world). Very few people realise the essential role that Australia plays in understanding the way volcanic ash behaves in such an active region. This is despite Australia has only a few isolated or insignificant volcanoes itself. Like the role of the VAAC, Australians don’t realise just how significant volcanism is to our second nearest neighbour (or indeed our nearest one, Papua New Guinea).

Readers of my blog will be aware that I focus almost entirely on the geology of the Northern Rivers, Eastern New England Tablelands and Mid North Coast areas of the state. Regular readers will also be aware that on occasion I indulge myself with a discussion or some opinions on geological matters elsewhere. Indonesia is just too important from a geological perspective to ignore. Having Indonesia come to our attention only when immigrants on boats are reported, volcanoes affect plane flights to Bali or the name Chapelle Corby is mentioned misses how much we are involved in and how much more we should be involved in managing volcanic hazards in our region. Including supporting Indonesia in its efforts to keep people safe.

Here are some selected facts about dangerous volcanoes:
  • Volcanic eruptions can be compared by a logarithmic scale called the Volcanic Explosive Index (VEI). 
  • VEI 0 are small explosive eruptions, VEI 8 are huge catastrophic eruptions. 
  • All recorded eruptions of VEI 6 or greater has killed someone. 
  • Approximately 50% of recorded eruptions of VEI 4-5 have killed someone. 
  • The majority of deadly volcanoes (VEI 6 or less) claim about 80% of their victims between 7 and 10 kilometers from the eruption. 
  • Lava causes only 0.34%-0.79% of deaths from eruptions. 
  • Pyroclastic flows cause between 33-46% of deaths from eruptions. 
Here are some selected facts about Indonesian volcanoes:
  • Monitoring the effect of volcanic ash in Indonesia is the responsibility of the Australian Bureau of Meteorology (via the Darwin VAAC). 
  • On average for every volcano that erupts in Indonesia, 27 people will die.
  • Five volcanoes have has significant (and recurring) eruptions already this year (Jan-Feb 2014). Those are Sinabung, Saiu Island, Kukano, Raung and Kelut. 
  • The largest explosive eruption known occurred at Toba about 30 000 years ago. 
  • In 1815 Mount Tambora erupted killing approximately 60 000 people and led to the “year without a summer” in Europe. 
  • In 1883 Krakatoa erupted with the resulting in approximately 36 000 deaths, the sound of the eruption was reportedly heard in many parts of Australia. 
  • Approximately 76 different volcanoes have erupted in Indonesia in the last ~500 years. Most of these erupting frequently. 
Here is an example of what people are trying to do about the dangers of volcanoes in Indonesia: http://citiesonvolcanoes8.com/. This is a geology related conference that people in Australia probably never hear about.

More information on the Darwin VAAC can be found here.

*Auker, M. R., Sparks, R.S.J., Siebert, L., Crosweller, H.S. & Ewart, J. 2013. A statistical analysis of the global historical fatalities record. Journal of Applied Volcanology 2:2
*Smithsonian Institution. Smithsonian Institution / USGS Weekly Volcanic Activity Reports (All editions January-February 2014)