You needed some pure science for your Monday
First time my own personal equipment has detected a volcanic eruption
(Um… published slightly before Monday because I needed the link, carry on.)
There is a well-known essay at Nautilus that I share with students whenever we cover volcanoes called The Sound So Loud That It Circled the Earth Four Times. The article is about the tremendously powerful eruption of Krakatoa on August 27, 1883. The eruption was heard, audibly, 3000 miles away. Observers closer to the event found it apocalyptic.
The British ship Norham Castle was 40 miles from Krakatoa at the time of the explosion. The ship’s captain wrote in his log, “So violent are the explosions that the ear-drums of over half my crew have been shattered. My last thoughts are with my dear wife. I am convinced that the Day of Judgement has come.”
And, and this is why the article is so titled, the sound wave produced by the eruption circled the entire planet, detected as a pressure spike by weather stations around the world.
By 1883, weather stations in scores of cities across the world were using barometers to track changes in atmospheric pressure. Six hours and 47 minutes after the Krakatoa explosion, a spike of air pressure was detected in Calcutta. By 8 hours, the pulse reached Mauritius in the west and Melbourne and Sydney in the east. By 12 hours, St. Petersburg noticed the pulse, followed by Vienna, Rome, Paris, Berlin, and Munich. By 18 hours the pulse had reached New York, Washington DC, and Toronto. Amazingly, for as many as 5 days after the explosion, weather stations in 50 cities around the globe observed this unprecedented spike in pressure re-occuring like clockwork, approximately every 34 hours. That is roughly how long it takes sound to travel around the entire planet.
It is not video from the 1883 eruption, of course, but that same Nautilus article includes video of a small modern eruption in Papua New Guinea which is remarkable because you can see the shockwave moving through the air (and then hear it when it arrives at the boat).
Well, now we’ve all lived through something like that
Well, now we’ve all lived through something like that. On Saturday morning (eastern time for the US), an underwater volcano in Tonga erupted. The eruption was captured in satellite photos.
The footage below really gives you some idea the size of the eruption. And note that especially in the second and third sections of the footage below you can see the shockwave moving out.
The eruption was heard, audibly, as far away as Alaska.
And minor tsunami were produced as far away as Chile.
And, just like in 1883, barometric pressure stations recorded the pressure wave as it moved by.
Now if you check the time stamp in the above, the initial pressure spike reached Michigan around 9:30 AM on Saturday. And some people in the replies to the above tweet mentioned that they seemed to observe the spike of the pressure wave moving past even on their personal weather stations.
Well, we have a backyard weather station so I thought, shoot, I have to check that. Here is the pressure recorded on Saturday. Each shaded region horizontally is one hour of time, starting at midnight.
It doesn’t look like much, but I have circled what does look like a potentially anomalous pressure spike. And what time did that spike occur? Roughly 9:15 - 9:30 AM, right on time. So, although I can’t say this with 100% certainty, I am pretty confident our humble little backyard weather station successfully recorded the “sound” produced by a volcanic eruption on the other side of the planet. How neat is that?
(The, uh, weather station is behind me in this summer photo, behind me!)
Very cool!
Great compilation of videos, thanks!