The natural first reaction to such a headline for an advanced reader would be to go to USGS.gov to check the information, and his first thought would be: "The author is crazy."
Indeed, the US Geological Survey does not write anything about 1,000,000 earthquakes in the Yellowstone area. However, there is no need to rush to conclusions, let's look at the background of the situation.
On February 8, 2018, a new swarm of earthquakes began in the Maple Creek area (or the old one that began in the summer of 2017 continued), the official number of which has exceeded one thousand today. Since the US Geological Survey makes no sense to tell the truth, only the truth and nothing but the truth, and the rest of the volcanology adepts obviously had no time to speak, we, INFOMAX, undertook the difficult and thankless mission of covering the situation, for there seemed to be no one else. And we did a lot of stuff about it. The material is called
Yellowstone is preparing to erupt: there is a critical volume of melt in the upper magma chamber.
The article, of course, does not pretend to be a scientific work, and we tried to explain everything as easily as possible. The essence of the material was that in the top (uppermost) magma chamber (it formed in the Maple Creek region), a critical volume of melt is observed (judging by the readings of seismographs). Seismographs behave as if they register not the vibration of the rock, but vibrations in a viscous liquid, on the basis of which we concluded: more (or about) 50% of this very viscous liquid (magmatic melt) has collected in the chamber, which is a signal of the movement of magma to the surface and an imminent eruption. And although the magma is not visible visually, everything is perfectly recorded graphically.
In seismology there is such a thing as volcanic (harmonic) tremor, observed exclusively on volcanoes before an eruption. If tectonic tremor is associated with the movement of solids (for example, vibration of lithospheric plates), then volcanic tremor is generated by resonant vibrations of a viscous liquid - melt in a magma chamber.
Promotional video:
The figure above shows an example of a volcanic (harmonic) tremor of an underwater volcano just prior to an eruption. The lower part of the figure shows the unprocessed signal recorded by the hydrophone, and the upper part of the figure reflects the same signal, but presented as a seismic spectrogram.
Since the hydrophone is like a “seismograph for water” (their principle of operation is similar), we can see from the figure that the magma wave is characterized by double bursts, going one after the other and falling within the interval of 960 seconds.
Now open isthisthingon.org and take at random any seismogram for the end of February, for example, from the Flagg Ranch, WY sensor:
Look at the seismometer readings for 19.30-20.00 local time. We see two successive seismic bursts, which together form a cycle of 16 minutes, that is, the very 960 seconds (we, for clarity, stretched the 960-second phonogram of the underwater volcano proportionally):
There are a lot of such 16-minute cycles on the sensors. The seismic tremors under Maple Creek are quite strong, so it is better to look at the seismograms not from there, but from the surrounding areas, where smaller seismic shocks are already damped and more clearly.
For any seismologist, this picture is obvious: instruments register the movement of magma, not solid matter. And if so, then the magma in the upper reservoir is not less than 50%.
This is not an absolute sign that there will be an eruption right now, but it is a direct sign that the melt has begun to melt / break the magma chamber, from the moment of which there is usually not much time before the eruption.
As always, when publishing such materials, there were people who began to teach us. One enlightened seismologist from Australia, in particular, began to explain to those around him the equations of motion of waves inside viscous media, which he studied, watching how the engine oil he had drained from the engine of his vehicle splashed. We studied these equations at the university, at the specialized faculty, therefore, unlike the sofa expert from Australia, we and the forum users arguing with him turned out to be right. And so much so that they themselves did not expect: the magma chamber under Maple Creek is collapsing before our eyes.
Open isthisthingon.org again and look at seismograph readings for March 3, 2018, for example, data from a seismograph installed on a lake in the Yellowstone Nature Reserve, abbreviated as LKWY (Lake, Yellowstone Park, WY).
We see the following picture.
In seismology, such volcanic activity has been described recently and is called the term "drumbeat earthquakes", that is, high-periodic repetitive earthquakes accompanying the incremental upward movement of viscous magma and resembling drumbeat.
In this picture, we see a seismogram, provided by seismologist Janine Krippner, illustrating the "drumbeat earthquakes" on the example of St. Helens volcano, the October 1, 2004 eruption.
St. Helens is an active stratovolcano located in Skamania County, Washington, USA, 154 kilometers south of Seattle. In 1980, it exploded, before which the recorders installed in the vicinity produced a strange seismic picture, an example of which is given above (since then, such pictures are there before eruptions all the time). These vibrations are low-frequency and are not audible to the human ear, but if you adjust them to the threshold of audibility, you get a sound similar to a drumbeat:
Dr. RICHARD IVERSON (US Geological Survey), in an interview with one of the TV channels in 2006, explained the situation as follows, commenting on the next eruption of St. Helens in October 2004:
CHRISTOPHER JOYCE (host): What makes these hellish underground sounds coming from the inside of the mountain? A gang of underground trolls? Giants rushing out?
Dr. RICHARD IVERSON (US Geological Survey): No, these are not trolls or giants in an underground cave. These are small earthquakes that usually occur about once a minute and repeat for more than one year, and today there are more than a million. And these are very low frequency sounds that are difficult to hear, so scientists made them 60 times faster for them to analyze. What we are hearing is a recording of the vibration of the ground just a few hundred meters from the air vent where St. Helens shot its summit in 1980. Molten magma rises up the central channel of the volcano, trying to escape. As he approaches the vent at the top, it solidifies into solid rock. In fact, it turns out to be a huge enormous tube twice the size,than the Empire State Building. This solid rock, in turn, slides and grinds the adjacent rock, forming the walls of the volcanic channel. And what we believe we are recording with these seismometers is the vibration of the earth that is generated every time there is a small momentum of this movement in a sliding type.
National Geographic News in a 2006 study, using the same eruption as an example, explains the mechanism of the "drumbeat earthquakes":
Dr. Iverson (Volcanic Observatory of Canada): Imagine that you are moving a heavy weight on a spring over a hard, non-smooth surface. Until the spring reaches a certain critical stress level, the load does not move, after which it makes a small jerk. The sequence of such jerks creates many small earthquakes.
The authors from the Ural Federal University in Yekaterinburg carefully studied the eruption of St. Helens, after which they published an entire study in the European Physical Journal, on the basis of which (that is, based on the registration of "drum roll") they predicted the eruption of the volcano Calbuco in Chile:
The logic of our Ural guys was simple: if seismographs register "drumbeats", then magma is moving a huge plug. And since the "drum roll" is a very weak seismic event and at a depth of 10 kilometers it is no longer heard, it means that the magma has moved the plug is already close and the volcano will soon explode - which happened first with Mount St. Helens, then with the Calbuco volcano, and now appears to be taking place in Yellowstone.
Here is what USGS.gov writes about this, describing the events with Mount St. Helens on October 1, 2004:
The eruption in 2004-2008 produced a huge number of earthquakes, in particular, more than a million of them were recorded during the formation of a new magma dome.
A particularly noticeable phenomenon observed during / on the eve of the last eruption was the so-called "drum roll" - a series of small earthquakes observed at regular intervals and is most likely associated with the movement to the surface of lava thorns, which, in particular, confirms the observation of the eruption of the Augustine volcano in 2006.
It is very strange that seeing the "drum roll" in the Yellowstone area, the US Geological Survey does not write anything about it. On the contrary, as we have already noted in the previous material, the USGS does not see microearthquakes there at close range, saying that there were several thousand seismic events in total and everything was within the normal range. But using the example of St. Helens, the USGS itself writes that "drum roll" is when seismic surges are counted not by thousands, but by millions.
We, of course, did not count every wave of the seismograms on the sensors from Yellowstone. Maybe there are a million bursts, maybe 500,000 or one and a half million - this is no longer of fundamental importance. What is important in principle is that, first, the magma chamber is being rebuilt. It is crumbling.
Secondly, the magma formed a new channel to the outside, which, due to its proximity to the surface, is rather cold and the magma plugged it with a plug. And this plug creeps out continuously, in jerks, which is recorded by seismographs.
Finally, thirdly, and most importantly, the plug is already very close, possibly a few hundred meters from the surface, since at the official depth of the upper magma chamber (8-10 km) such weak seismic events as friction of pieces of rock against each other are not detected by the sensor.
The most important question in all this, of course, is "When will it explode?" We cannot give an exact date. Technically, if a "drum roll" is recorded on a volcano, the eruption can begin at any moment when the cork of cooled magma is knocked out like a cork from a bottle of champagne. Nevertheless, we do not know the moment when this will happen, and only together with everyone we follow the development of events.