Tonga Eruption Pressure Wave Caught on a Raspberry Pi Thousands of Miles Away — Three Times in a Row
Bioinformatician and electronics enthusiast Sandy Macdonald was able to capture the pressure wave from the volcanic eruption in Tonga using a Raspberry Pi and a pressure sensor — despite being over 16,000 kilometers (10,000 miles) away.
Late last week the uninhabited volcanic island of Hunga Tonga–Hunga Haʻapai erupted in what has been preliminarily described as the largest volcanic eruption of the 21st century so far. Humanitarian efforts to assist victims of the tsunamis that followed continue, but even those a safe distance from the epicenter have been able to detect the resulting pressure wave — and calculate its speed, too.
The Tonga volcanic eruption pressure shockwave measured on a hastily set up @pimoroni BME280 sensor and @Raspberry_Pi in York, UK. That's 16,270 km away, and taking 14h 20m to get here gives a speed of 1,135 km/h or 315 m/s!#Tonga #TongaVolcano pic.twitter.com/b4JzUtdih9— Sandy Macdonald (@sandyjmacdonald) January 15, 2022
"The Tonga volcanic eruption pressure shockwave measured on a hastily set up Pimoroni BME280 [pressure] sensor and Raspberry Pi in York, UK," Macdonald wrote of his citizen-science experiments into tracking the eruption. "That's 16,270km [around 10,110 miles] away, and taking 14h20m to get here gives a speed of 1,135km/h or 315m/s [around 705 miles per hour]!"
The sensor recorded the shockwave as a sudden spike in pressure, followed by a sudden drop in pressure to well below previous levels as the shockwave passed before returning to roughly where it had started.
Impressively, the same sensor setup caught the shockwave as it came the long way around the globe — and again as it made a full orbit: "It's 23,805km [14,792 miles] coming round the other way," Macdonald noted following the recording of the initial pass, "so at the same speed I'd expect another wave to pass at about 1am."
I *think* this is the pressure wave (atmospheric gravity wave?) being detected in York, UK after another full orbit of earth, i.e. second time around, at ~06:40 GMT. Shape looks right. 56,345km travelled, still pretty much same speed, lower magnitude. #Tonga #TongaEruption pic.twitter.com/l7ZDWqamgd— Sandy Macdonald (@sandyjmacdonald) January 17, 2022
"I did indeed capture the east to west pressure wave from the Tonga veruption at about 01:40 GMT," Macdonald wrote of the second reading — followed by a third: "I think this is the pressure wave (atmospheric gravity wave?) being detected in York, UK after another full orbit of earth, i.e. second time around, at ~06:40 GMT."
"Shape looks right. 56,345km [35,011 miles] travelled, still pretty much same speed, lower magnitude. In fact, when I tone down the smoothing on the line, the shape of the peak matches the peak of the first pass almost exactly."
All Macdonald's readings, including annotated graphs, are available on his Twitter thread.