Monday, 11 June 2018

The NSW/QLD border geological mess and other matters - Talk at Binna Burra

This year marks the 85th birthday of the Binna Burra Wilderness Lodge in Southern Queensland. As part of the 85th celebrations the lodge has invited many people to give talks at the lodge between the 20th and 24th of June. There are many interesting science and nature talks open to the public on these days and two of the talks will have a geological theme. The Lodge is situated on the northern side of the Tweed volcano and the landscape and ecology of the area is intimately connected with the geological history of the area.

I will be giving a talk on the evolution of our understanding of the Tweed Volcano over the years and how politics can affect how we scientifically look at our part of the world. My talk will be on Friday 22nd June at 9.30am. On Sunday 24th, Warwick Willmott will be giving a more geology overview walk and talk including discussions on how the Tweed Volcano and Hawaiian Volcanoes have many similar characteristics.

UPDATE: Due to personal matters I have had to cancel my talk. The Talk by Warwick Willmott on Sunday is unaffected.

The details of my talk are as follows:


Talk title:
Our understanding of the Tweed Volcano: A Learning, Unlearning, Forgetful and Confused Experience.

Abstract:
The landscape of the NSW/QLD Border (Lamington and Tweed areas) being the result of a single volcanic centre, has been recognised formally for less time than the establishment of Binna Burra Lodge (only 70 years). Since this first realisation, many researchers have added to understanding of how the landscape has evolved. However, sometimes even in our modern and scientific world new knowledge can get lost, be ignored, or repeat old myths. This talk will cover some of the evolution of our understanding of the Tweed Shield Volcano and examine some of the persistent ‘popular science’ myths of this landscape.


For details of events being held at Binna Burra Wilderness Lodge you can visit their facebook page:

https://www.facebook.com/pg/binnaburra/events/?ref=page_internal

Saturday, 26 May 2018

Blog Update #12

Firstly, I need to apologize to all the commenters who have not had their comments published. The old regular visitor crowd will have noticed the blog has become fairly inactive over the last few months. Given the number of comments placed and the continuing interest (including an invitation to speak just this morning) I should really do a lot more... and I will.

I have recently had a few interesting journeys which included work near Nymboida on a new quarry and also visited an old quarry with some really interesting fossils. I've also noticed some interesting rock alteration in a road cutting on the way to Valla and I've been spending some time at a friends place near Glencoe at a place called Mount Mitchell. All of these are worth blog posts and I shall try and get to them at a rate of at least one a fortnight.

Thanks to everyone continuing to support this page. Please feel free to continue to comment but if you have something specific please feel free to email or phone me. My details are on this page: https://nrgeology.blogspot.com.au/p/hees.html

Thursday, 25 January 2018

Nambucca Heads earthquakes follow up

Yesterday, following the rare experience of a noticeable earthquake in our region, I provided a very rough map of the location of earthquakes in preceding 24hours to the one many people felt. I have since incorporated earthquakes since and for the week before. I've also increased the area we are looking at.

Mapping is all about enough data, and enough decent data. Collecting the data is essential and then looking at it so see whether it adds to the story helps us understand the world in which we live. Geoscience Australia provide an excellent online service to the public showing all the earthquake activity in our Country. Yesterday's post had enough data to demonstrate that there appears to be little relationship between inferred or known faults in the region and the location of earthquakes. More data since means more interesting features!

A comment from a reader asked about the trace of the Demon fault system (a system that is very evident even today despite it being apparently inactive for many millions of years). I have included a thick pale blue line that roughly approximates the Demon Fault system strike.

The map I have just updated implies that there is a fault system previously unknown. I have included a line that approximates the pattern of many quakes in area. What is interesting is that the apparent line of most quakes is perpendicular to the old Demon Fault. It is also interesting that the 'major' 4.2 quake is separate from the apparent line of quakes experienced in the last week or so. It is likely that the quakes in the Nambucca area are a parallel line of stress to the most frequent quake trend.

Either way, the map says more that I can so have a look and tell me what you think.

 *Update: At least three more quakes have been identified (one occurred since the above map) and another couple which was subsequently identified after cleaning out the background 'noise.

I also note that the quakes were almost entirely situated in a structural block known as the Nambucca Block. I guess another post will have to be done since the Nambucca Block provides insights into the way the New England Orogen has formed (Shaanan, Rosenbaum & Ranauld 2016).



Wednesday, 24 January 2018

Yes, I felt that Earthquake too

Earthquakes are a bit infrequent in our part of the world. So, when one is big enough to feel happens there is usually much excitement.

While in my home office a few hours ago (1.30pm this afternoon) I felt a strange sensation and the roof of my studio shook. About 1 minute later, my wife came up from the house and asked if I had felt something, because the house shook for a moment. So, onto trusty Geoscience Australia Earthquakes page I went. Sure enough a substantial (by our standards) quake hit somewhere under the ground near Urunga.

I've put together a quick map which shows all the mapped major faults in the area (noting that most of them are actually inferred). I have overlain the last 24hrs worth of quakes to see if there is a correlation. There appears to be very little if any. But that is unsurprising given most faults have probably been inactive for millions of years. But I suppose interesting anyway. Note that the data had not been double checked by Geoscience Australia when I put this together.*
*Since posting the above, the earthquake epicentre has been updated to near Nambucca Heads the hypocentre being approximately 10km below Nambucca Heads.