I love learning new things every day! Today, filtering data let me to some fun artifacts about mining and earthquakes.
I’m currently working on some personal projects on data analysis and visualization. I downloaded some earthquake data from the US Geologic Survey. I requested only data for earthquakes in the US, but a fair number of seismic events in Canada and Mexico crept into the data. While filtering out that data, I discovered that many of the events were recorded as happening near Princeton, British Columbia. I love hiking and exploring in the great Pacific Northwest, so I took an interest in what might be generating this activity. The Cascades are home to many volcanic features, and I was excited to think that one I hadn’t heard of might be restive. A very cursory glance at the map showed no such features, but a cursory Google search led to a few interesting discoveries.
The first thing Google led me to was an indication that though these events may not be generating attention, they have not gone unnoticed. One website shows that there have been about two dozen events in a specific area near Princeton over the last month. An older article in Canadian media showed previous earthquakes in the same area in 2015, with the intriguing statement that earthquakes in the interior of British Columbia are “quite rare.” Google eagerly led me to a YouTube video whose producer had observed an earlier cluster of seismic events and concluded they were evidence of earthquakes caused by “fracking.” (Here in Texas, we hear quite a bit about fracking.)
The video producer was pretty adept at showing the indicated location on Google Earth, where the presence of some structures led him to instantly conclude that we were viewing “fracking on top of a mountain.” He somehow managed to segue to a more valid observation that the mountain site was actually a copper mine (which was confirmed by a Canadian government press release and other sources.) The producer then moved on to some commentary about mining waste, coal production, and eventually back to fracking. However, I returned to my own research with the US Geologic Survey (USGS.)
I learned that there are a number of mining activities that can be detected by seismographs. The USGS makes an interesting distinction between mining and earthquakes caused by mining. The USGS calls energetic mining events that are directly detected by their seismographs “mining seismicity.” The USGS calls true geologic events triggered by mining “mining induced earthquakes.” Over the years, USGS has adapted their rules on when such detected blasting and other events are included in which of their earthquake catalogs and other seismic event catalogs. Likewise, they have adapted their event catalogs for underground nuclear testing events.
The language used is precise because of the need for clarity on cause and effect. There is no question that earthquakes can trigger events in mines, such as collapses. There is no question that some mining activity (such as blasting) is a seismic event. There is also substantial evidence that mining (and other earth transforming activities like dam-building) can trigger earthquakes by redistributing forces or changing rock properties..
In returning to my own project, I discovered that the events in the USGS data I was working with were actually tagged as earthquake, “explosion,” or “quarry blast.” I have not yet determined how USGS makes a distinction between those last two tags.
As a bonus factoid, I learned that the hypothetical limit to earthquake power would be a 12 on the Richter scale, as it would take a fault larger than the Earth to create a quake more powerful.
When I have completed my earthquake project, I will share the results.
(Image courtesy of Sebastian Pichler at Unsplash.)