[GPlates-discuss] GPlates-discuss Digest, Vol 59, Issue 6
Christopher Scotese
cscotese at gmail.com
Tue Oct 8 16:06:04 AEDT 2019
To all,
Attached is a copy of the powerpoint (as a pdf) I gave in Vancouver a
couple years ago (that Bruce mentioned). I was trying to have a look at the
uncertainties in plate models by comparing the geographic variance between
various plate models. Have a look.
Chris Scotese
Prof. Christopher R. Scotese, Director, PALEOMAP Project
134 Dodge, Evanston Illinois 60202, 817 914 7090 (cell)
*I know this is a long signature, but I think you'll enjoy the treasures
hidden within.*
My latest animation (uploaded June 1, 2019) https://protect-au.mimecast.com/s/GoXxCROAQotzvQvKu9StNM?domain=youtu.be
Wow! Check out the interactive paleoglobes at:
https://protect-au.mimecast.com/s/MEs9CVAGXPtRxXx4iz5MFf?domain=dinosaurpictures.org. You can see where your home
was located at the time of the Permo-Triassic extinction or any other time
in Earth History.
Digital elevation models of all of the paleogeographic maps are now
available at:
https://protect-au.mimecast.com/s/4aOeCWLJY7iW5x5piKmEPj?domain=earthbyte.org
GPlates compatible maps and software that can plot your data on the maps,
can be freely downloaded at:
https://protect-au.mimecast.com/s/PfELCXLKZoizXGX6ukSe84?domain=earthbyte.org
View >50 Scotese animations at: https://protect-au.mimecast.com/s/XknOCYWL1vi4LgL0TMqpqk?domain=youtube.com
This ESRI website features my maps & animations and has some nice
interactives:
https://protect-au.mimecast.com/s/J88fCZYM2VFp5x5mSPT8Ci?domain=apl.maps.arcgis.com
Paleogeographic Atlases can be downloaded at:
https://protect-au.mimecast.com/s/tZMcC1WZXri9MOMjUyNrtG?domain=uta.academia.edu
Map Folios for different time periods can be downloaded at:
https://protect-au.mimecast.com/s/dZthC2xZYvC9p6pxU0npk_?domain=uta.academia.edu
An archive of Scotese publications can be found at:
https://protect-au.mimecast.com/s/qUNsC3Q8Z2FEpxp8SOPEiV?domain=researchgate.net
Download Google Earth (kml) versions of maps at:
https://protect-au.mimecast.com/s/-E5BC4QZ1RFvB6BjsXwsHX?domain=globalgeology.com
Download Scotese CV with links to publications:
https://protect-au.mimecast.com/s/Ajl-C5QZ29FDZRZnHjuemO?domain=uta.academia.edu
Lecture given at the Geological Society of London on October, 2017
https://protect-au.mimecast.com/s/BUpfC6X13RtBrMr3HldRBH?domain=youtube.com
Hear Chris play the "Paleogeographer's Song"
https://protect-au.mimecast.com/s/mFy1C71ZgLtJAyAPfE_shn?domain=youtube.com
"Sailing away on uncharted seas, who knows what we might find.
You needn't go far to take this trip because the journey's through your
mind."
On Mon, Oct 7, 2019 at 6:22 PM <
gplates-discuss-request at mailman.sydney.edu.au> wrote:
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>
> 1. Re: Estimating uncertainty in plate positions and motion
> paths (Eglington, Bruce)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 7 Oct 2019 23:22:12 +0000
> From: "Eglington, Bruce" <bruce.eglington at usask.ca>
> To: GPlates general discussion mailing list
> <gplates-discuss at mailman.sydney.edu.au>, Sabin Zahirovic
> <sabin.zahirovic at sydney.edu.au>, "mdarin at uoregon.edu"
> <mdarin at uoregon.edu>
> Subject: Re: [GPlates-discuss] Estimating uncertainty in plate
> positions and motion paths
> Message-ID:
> <
> QB1PR01MB261078B6599DBB72C3C1A80C9F9B0 at QB1PR01MB2610.CANPRD01.PROD.OUTLOOK.COM
> >
>
> Content-Type: text/plain; charset="utf-8"
>
> Hi Ben
> Agreed that one can calculate something. The issue is what it means.
> Yes, to illustrate variability between models but, if none of them are
> correct, there is no way to assess this. However, just doing the
> calculations forces us all to think of what we want or mean to portray so
> the exercise is valuable. A simple illustration from an area I am more at
> home with is: the average age of the Earth is about 2000 Ma, based on
> available geochronology but this does not tell us anything useful. Working
> through the data does, however, show where we might have bias, uneven data
> distribution and a host of other information.
>
> Chris Scotese showed a comparison of various global models at the RFG
> conference a year or so ago, using spots for various major cities on
> different continents. It was very interesting because it showed
> similarities between some models and vast differences for others, all of
> which highlighted areas and time intervals requiring research and I think
> that much of what you are doing will be of similar use. Go for it and show
> us how to develop methodology for when better data are available.
>
> Bruce
>
>
> Bruce Eglington (Ph.D.)
> Murray Pyke Chair
>
> Geological Sciences
> 114 Science Place
> Saskatoon
> Saskatchewan
> S7N 5E2
> Canada
>
> bruce.eglington at usask.ca<mailto:bruce.eglington at usask.ca>
> Ph: +1-306-966-5732
>
> [cid:image002.jpg at 01D57D33.C0C815C0]
>
> From: GPlates-discuss <gplates-discuss-bounces at mailman.sydney.edu.au> On
> Behalf Of Ben Mather
> Sent: Monday, October 7, 2019 16:15
> To: Sabin Zahirovic <sabin.zahirovic at sydney.edu.au>;
> gplates-discuss at mailman.sydney.edu.au; mdarin at uoregon.edu
> Subject: Re: [GPlates-discuss] Estimating uncertainty in plate positions
> and motion paths
>
> Hi all,
>
> Great discussion! But just to clear up any confusion: the parameter
> uncertainty problem is less complicated than the inference problem some are
> alluding to. If you want the total uncertainty of the model given the data,
> then a likelihood function would need to be constructed that links a
> reconstruction to a set of observations (palaeomagnetic stripes, fossil
> records, etc.) and compares the misfit. From there you would sample the
> posterior probability, using a MCMC algorithm, and build up an ensemble of
> realisations until you can extract the posterior uncertainty. A frequentist
> approach may be preferable in some linear cases e.g. anomaly picks - thanks
> for the reading material, Douwe. Alas, as Sabin pointed out, all of this is
> outside the scope of what can be achieved short term.
>
> Rather than finding the posterior uncertainty, you can compare a suite of
> reconstructions using all the different rotation files available and
> quantify their collective uncertainty through time. The uncertainty on
> Arabia-Eurasia convergence will not reflect the total uncertainty of the
> model given the data, but it will reflect the uncertainty between rotation
> files. Admittedly, this is far from perfect, given the small set of
> reconstructions we have available and the weighting bias I mentioned
> earlier, but it's a start...
>
> I hope that gives a bit more insight into what I had in mind. Hopefully
> this will provide a better framework to assess and compare models - and, as
> Bruce suggests - illustrate where and when certain models are thought to be
> better constrained than other parts.
>
> Cheers,
> Ben
>
> --
> Dr. Ben Mather | Computational Geophysicist
> Room 418, Madsen Building F09
> School of Geoscience, Faculty of Science
> The University of Sydney, NSW 2006
> m +61 422 470 117
> w benmather.info<https://protect-au.mimecast.com/s/igN2C81Zj6tK6Q6JSgK5Px?domain=benmather.info>
> t https://protect-au.mimecast.com/s/Wr50C91ZkQtpkxkZSKWiyI?domain=twitter.com<https://protect-au.mimecast.com/s/3HZOC0YZWVFLG4GEsRZitb?domain=twitter.com>
>
>
> On 2019-10-07 21:43:42+11:00 GPlates-discuss wrote:
> Hi Mike and team,
>
> I agree with Bruce, using alternative models is not likely going to
> capture the uncertainty present in the Arabia-Eurasia convergence. If one
> is just looking at the Arabia-Eurasia convergence rate during a time where
> Atlantic seafloor spreading is occurring, then one probably wouldn?t need
> to take into account the absolute reference frame, but just evaluate the
> uncertainties across the relative plate motion hierarchy (Arabia ? Africa ?
> North America ? Eurasia). However, as Bruce pointed out, other constraints
> might be useful, especially if intraplate deformation is significant. The
> reality at the moment is that this is not easy to do, and would generally
> need to be done on a case-by-case basis, by trawling back through the
> rotation file and checking whether uncertainty ellipses are published for
> the poles used, and so on. Would be cool to have this in GPlates one day!
> In terms of Ben?s suggestion, it might be interesting to see what different
> models propose/predict for the Ar
> abia-Eurasia convergence. There?s a bunch of models to download from
> here:
> https://protect-au.mimecast.com/s/e9zgCgZowLH7ANAgSYHxwU?domain=earthbyte.org
> (EarthByte models, Chris Scotese model, etc.), and I think Douwe van
> Hinsbergen and team have some GPlates-related files here:
> https://protect-au.mimecast.com/s/WvrdCjZrzqHvnAn6s4wKsA?domain=geologist.nl
>
> Cheers,
> Sabin
>
> --
> DR SABIN ZAHIROVIC | Postdoctoral Research Associate
> School of Geosciences | Faculty of Science
>
> THE UNIVERSITY OF SYDNEY
>
> Rm, 404, Madsen Building F09 | The University of Sydney | NSW | 2006
> M +61 416 775 589 P +61 2 9351 2467
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> https://protect-au.mimecast.com/s/gS1vCk8vAZtpO4OLSx5Tfi?domain=earthbyte.org<https://protect-au.mimecast.com/s/o-HtClxwB5Cv2k29smFVdZ?domain=earthbyte.org> | R
> http://www.researchgate.net/profile/Sabin_Zahirovic
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> From: GPlates-discuss <gplates-discuss-bounces at mailman.sydney.edu.au
> <mailto:gplates-discuss-bounces at mailman.sydney.edu.au>> on behalf of
> "Eglington, Bruce" <bruce.eglington at usask.ca<mailto:
> bruce.eglington at usask.ca>>
> Reply-To: GPlates general discussion mailing list <
> gplates-discuss at mailman.sydney.edu.au<mailto:
> gplates-discuss at mailman.sydney.edu.au>>
> Date: Monday, 7 October 2019 at 8:21 am
> To: GPlates general discussion mailing list <
> gplates-discuss at mailman.sydney.edu.au<mailto:
> gplates-discuss at mailman.sydney.edu.au>>, "mdarin at uoregon.edu<mailto:
> mdarin at uoregon.edu>" <mdarin at uoregon.edu<mailto:mdarin at uoregon.edu>>
> Subject: Re: [GPlates-discuss] Estimating uncertainty in plate positions
> and motion paths
>
> Hi
> The issue is actually much more difficult to conceptualise because
> different parts of different models are variably uncertain and there is no
> reason to assume that the average of available models is any closer to
> reality. I doubt that motion paths are going to resolve better models from
> worse, other than to identify plate motions that are too fast, etc. In
> order to better constrain models, we will needs to have far more
> comprehensive data sets that can be ?draped? over the kinematic blocks to
> assess matches and mismatches. One can already start some of this with data
> like palaeomagnetics, geochronology, etc and, to a limited extent
> geochemistry and geology. In most cases, though, we need data sets with
> much better temporal and spatial resolution than are currently available.
> There are lots of ways in which machine learning and AI could help, if only
> we had better organised, structured and relevant data.
>
> The best that can be said at present seems to be that each model can be
> tested for validity with localised data sets where sufficient detail is
> available, from which we can start to improve models.
>
> None of this is to say that we should not attempt to develop ways to test
> model comparisons in anticipation of improved data compilations. By doing
> so, we will have a better idea of how to assess and compare models. It
> would also be useful to somehow be able to illustrate which parts of
> individual models are thought to be better constrained than other parts
> (time, polygons, motion, etc). Something like this would certainly help
> address the very real need to quantify model uncertainties to help
> potential end users.
>
> Bruce Eglington
>
> Get Outlook for iOS<https://protect-au.mimecast.com/s/g44WCoVzGQi0r8ros8mlLh?domain=aka.ms>
> ________________________________
> From: GPlates-discuss <gplates-discuss-bounces at mailman.sydney.edu.au
> <mailto:gplates-discuss-bounces at mailman.sydney.edu.au>> on behalf of Ben
> Mather <ben.mather at sydney.edu.au<mailto:ben.mather at sydney.edu.au>>
> Sent: Saturday, October 5, 2019 4:39:49 AM
> To: gplates-discuss at mailman.sydney.edu.au<mailto:
> gplates-discuss at mailman.sydney.edu.au> <
> gplates-discuss at mailman.sydney.edu.au<mailto:
> gplates-discuss at mailman.sydney.edu.au>>; mdarin at uoregon.edu<mailto:
> mdarin at uoregon.edu> <mdarin at uoregon.edu<mailto:mdarin at uoregon.edu>>
> Subject: Re: [GPlates-discuss] Estimating uncertainty in plate positions
> and motion paths
>
> Hi Mike,
>
> Thanks for reaching out.
>
> In principle, if you had enough reconstructions (rotation files) you could
> build up an ensemble of plate models that would enable you to interrogate
> uncertainty information from (standard deviation, confidence intervals,
> etc.), but one of the key problems is it's unclear how to weight each
> reconstruction. For instance, one could always argue that the latest
> reconstruction is the "best" because it's the result of painstaking tweaks
> and adjustments of all those that came before it as a product of additional
> geological constraints.
> Nonetheless, if you see beyond this caveat, a qualitative comparison
> between the different models is still useful and some quantitative metrics
> can also be employed. Comparing the plate velocities and cumulative plate
> distance is relatively simple to do with motion paths, but it can give the
> false impression that the plate reconstructions do not agree at all. A test
> we are working on is to place a bunch of points equally spaced across the
> globe and measure the distance between these points through time for
> different rotation files. Essentially this is just comparing multiple
> motion paths across the globe. From there you would calculate
> (pseudo-)uncertainty maps of where the reconstructions agree and where they
> do not.
>
> This workflow is particularly suitable for pyGPlates because swapping
> rotation files a breeze, and it's easy to import other python modules that
> deal with statistical analysis. Once we have something in place (that
> works!) I'll send you the python scripts so you can customise it to your
> problem. Is that OK? Let me know if you have any other suggestions and if
> you would like to be involved with testing.
>
> Best regards,
> Ben
> --
> Dr. Ben Mather | Computational Geophysicist
> Room 418, Madsen Building F09
> School of Geoscience, Faculty of Science
> The University of Sydney, NSW 2006
> m +61 422 470 117
> w benmather.info<https://protect-au.mimecast.com/s/igN2C81Zj6tK6Q6JSgK5Px?domain=benmather.info>
> t https://protect-au.mimecast.com/s/Wr50C91ZkQtpkxkZSKWiyI?domain=twitter.com<https://protect-au.mimecast.com/s/3HZOC0YZWVFLG4GEsRZitb?domain=twitter.com>
>
>
> On 2019-10-05 05:25:49+10:00 GPlates-discuss wrote:
> Hello,
> I'm using GPlates to reconstruct the Arabia-Eurasia collision zone and to
> make a plot showing Total Arabia-Eurasia Relative Motion vs. Time. To do
> this, I fixed the Eurasia plate and then created a set of motion paths for
> points on Arabia. This worked great, as I was then able to export a text
> file containing the coordinates of each reference point at different time
> steps, which allowed me to calculate the distance that Arabia had traveled
> between each time step.
> However, there must be some uncertainty in the rotation model that is not
> currently reflected in the generated motion paths. I am wondering if and
> how I could generate error ellipses in map view for the motion paths, which
> would allow me to add error bars to each point on the plots that reflect
> the uncertainties in the locations of each reference point through time?
> This doesn't seem straightforward to me, so I am reaching out to the
> discussion list for suggestions. ?
> Thank you,
> Mike
> Michael H. Darin, Ph.D.
> Postdoctoral Research Associate
> Department of Earth Sciences
> University of Oregon
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