Mining Deformation Data on Mines

Formatting Fun

On this occasion of writing about mining we’ve chosen not to use our typical short form with loads of pictures in between :) Instead, it’s a bit more like a paper with tasty data at the end. We decided to change it up for once and allow for an easier long form. Enjoy the read, and if it seems a repeat of former content . . . then you are awesome, you’ve been keeping up.

Mining is, by far, one of the most important application potentials for the InSAR community. Here all of us working in this effort have a chance at increasing the safety of sites that are often overlooked and tremendously hard-working. An ode to mines, their staff, and communities is due but alas there’s never enough time!

Tailings Dams, Spoils Piles: Monitoring Mines

Using European Space Agency (ESA) Sentinel 1 (S1) data enables Ovela to assess deformation of nearly any site globally, at the millimeter scale, from a historic record since 2015. Thanks to a regular revisit frequency we are also able monitor a site twice monthly in an ongoing basis.

Ovela InSAR is based on persistent scatter points, which are areas that have a coherent signal over time. This allows us to be more accurate and resolute than in a differential InSAR process. As we are looking for persistent scatter over time, we are also able to display deformation in a time series – and update that series quickly. Depending on the location, the overflight takes place every 6 or 12 days. 

In the event a sensitive structure area does not have a persistent scatter point, we can typically resolve this through adjusting the system, or the use of a low-cost artificial reflector – a trihedral metal object – which we can provide.

This data history can be used to forensically investigate prior failures as well as correlate deformation data to manual and other data collection methods.

At its root, InSAR functions by taking very many radar ‘images’ of a site, ‘stacking’ them atop one another and finding a phase shift through the history.

It was historically delivered as a narrative report generated by a complex system of physics methods. We have dramatically changed the way in which data from the spacecraft is delivered.  

Ovela has automated collecting, processing, and displaying data from S1. This allows us to rapidly deliver monitoring results which are then displayed on our own web-GIS which is accessible, and easily used, on any smartphone from anywhere. They are coded for doppler shift relative to the satellite, where blue is vertical deformation (uplift) and red is downward (subsidence). When necessary this also enables us to give our users a vector.

Ovela is partnered with many signature civil structural engineering firms globally to review our results. We also provide the option of blockchain enabled security of the data flow from the space craft to the data display for security sensitive applications. 

Ultimately, it is Ovela’s unique use of automation and (A)rtifical (I)ntelligence that enable us to deliver better, faster, and more economically viable InSAR data than anyone on the planet.

InSAR should be used to monitor the rate of change in deformation trends in these sites. It can serve as a valuable forewarning. As we’ve mentioned before, in an emergency, terrestrial SAR devices are best suited to continue or “link” real time deformation trends to that of satellite InSAR.

Also, as you’ll notice in the images, vegetation and open fields are not consistently reflective - that means we cannot acquire an accurate signal from those areas automatically. We will work with an operator to best understand what is going on in a site they want to see where there is no auto detection of a signal. Often, there is in fact a signal but one that is getting filtered out if it is too erratic. Occasionally we will recommend trimming vegetation, or as mentioned above, using artificial reflectors.

A key example of this technique is in the Brumadinho failure as well as in the mine wall destabilization at Gongo Soco in Brazil. Those images are below together with other select sites. In all of these examples the data points you see were determined without us ever visiting the site, or using any sort of a reflector.

You can interact with much of our data by clicking ‘demo’ at this link:

Figure 1 Nov. 2017 to January 22, 2019 - Brumadinho, Brazil. Scale: 3cm

Figure 2 Same image as above, time series of a dam crest scatter point.

Figure 3 Gongo Soco, Brazil - mine wall failure March 2018 to May 2019

Figure 4 Gongo Soco SAR image above, North wall cumulative deformation exceeding 15cm in period

Figure 5 Sub-surface coal mining related catastrophic surface deformation resulting in widespreed structural failure – Poland

Figure 6 Time series of the above findings in the coal mining subsidence events in Poland.

Figure 7 Catastrophic aquifer depletion in Mexico City, Mexico - exceeding 50cm in the period 2017-2019.

Figure 8 Sub-surface hydraulic fracking operations resultant surface deformation.

Together with mine operators globally InSAR has the potential to dramatically improve safety. It’s up to us to make it happen.