The eruption of volcano tonga has taken many people by surprise. Meteorologists around the world were more excited than usual on Saturday afternoon. Several satellites in the Pacific Ocean captured the massive eruption of the Hunga Tonga volcano with unprecedented clarity, beginning to appear on their instruments. The sudden rise in the barometric map shows pressure changes, as expected when waves travel from the antipodal point at the speed of sound. The Tonga volcano is shaking the sky around the Earth, causing a small "atmospheric tsunami." For more information on this volcano, you can consult the article on Underwater volcanoes and their ecological impact And also on the eruption of the Tonga volcano.
Let's see how the Tonga volcano eruption in Spain was experienced and what the atmospheric consequences were.
Registration in the Balearic Islands
In Spain, the disturbances began at the observatory around 21:30 p.m. local peninsular time, according to Rubén del Campo, spokesman for AEMET. Meteorologist José Miguel Viñas explained that, in addition to the ocean tsunami that caused the catastrophic consequences of the recent island eruption, the shock waves from the explosion travel great distances and can be seen as far as Alaska and in the form of instantaneous discharges and pressure changes on a global scale.
At almost the same time, between 20 and 21 p.m., the retired meteorologist Agustín Jansa began to receive inquiries from several colleagues who asked him about the recorded values of sea level in the Mediterranean. One of the pioneers was Agustín, who from the 80s began to describe a phenomenon that occurs from time to time in the Balearic Islands, known locally as “meteotsunamis” or “rissaga”These sudden rises in water level occur when the atmosphere and ocean "couple" due to a sudden drop in pressure that occurs under very specific conditions, as occurred in the events of 1984 and 2006, and which can ultimately cause damage to ports. To learn more about the effects of tsunamis, see the article on radioactive tsunamis, which also describes phenomena in the Mediterranean. Catastrophic damage, such as the Citadella in Menorca.
Oscillations in atmospheric pressure
The meteorologist was able to observe fluctuations in atmospheric pressure and sea level off the coast of the Balearic Islands. This can be a bit unusual, and people were asking him if the fluctuations could generate a rissaga. Apparently, the conditions for this aren't right, but the truth is that some oscillations of several centimeters in the last few minutes of the storm were beginning to be very reminiscent of a meteotsunami, so the meteorologist strongly suspected the possible impact of the Tonga volcano eruption on the water. However, this meteorologist has been looking at atmospheric pressure records for 40-50 years, and this is the first time he's seen something like this.
If you look closely at the graphs, you can see that the sea is oscillating with amplitudes of 10-15 centimeters that later grew and in the morning the oscillations of up to 30 centimeters on the south coast of Mallorca and up to 50 centimeters in Ciutadella. The strongest oscillation is recorded on the 16th, at 8:00 local time. And although the measurements and numerical comparisons with different models still have to be made, he is convinced that it is the effects of the eruption, something he had never seen in his entire career.
What happened was a meteorological tsunami in the Mediterranean, but it was exciting because of the exposure of the volcano on the other side of the world. It is an oceanic oscillation that sometimes produces atmospheric pressure waves, like those produced by volcanoes in this case. Because the sea surface is in contact with the atmosphere, a sudden drop in air pressure tends to cause the sea surface to swell as atmospheric waves pass through, thus oscillating horizontally and causing a meteotsunami in an attempt to return to its equilibrium position.
The big difference with the usual meteotsunamis in the Balearic Islands is that here the pressure and the rapid changes in sea level are not simultaneous but uncoupled, so the Proudmann resonance (the difference between the cause and the sea level) is coupled effects. ) is unlikely to be one of the commonly occurring amplification factors in major meteorological tsunamis. Other amplification factors, such as the platform resonance, the ramp effect (tsunami effect) or the port resonance yes they could be present, although specific studies are needed to see in what proportions they acted.
Observation of the Tonga volcano in Spain
What is unique about this weekend's volcanic eruption in Tonga is that we have a wealth of information about the phenomenon from space and various instruments. Nahúm Chazarra admits that we have never been able to measure something like this in so many ways. “We have improved a lot in terms of instrument capabilities: we have more satellites in space monitoring the surface of the Earth, which allows us to observe this phenomenon in great detail".
As for the propagation of pressure waves, scientists were amazed at the breadth and clarity of the recorded data. González Alemán said: “It is well documented that every time this type of volcanic eruption occurs, there are shock waves, but these shock waves that can travel around the world only happen occasionally. We can assume that the previous ones are similar, but we cannot say for sure because we do not have the instruments that we have now.
Experts warn that this atmospheric jolt is spectacular, but only anecdotal for meteorology. “It does not have the ability to affect the weather, it only affects the pressure”, explains González Alemán. "They are shock waves, a counterproductive result that creates such abrupt changes in temperature and air pressure that they exceed the speed of sound, as we see when airplanes break the sound barrier."
Chazala added that from a volcanology perspective, “all the data collected during this eruption will help improve our understanding of these phenomena, and in terms of geological hazard, a very important piece of information is the modeling of tsunamis from eruptions, for example.” It’s also a good reminder for González Alemán, “a volcano could erupt there at any time, which could lead to a relatively cold year,” as has happened in the past. To learn more about the influence of volcanoes on the climate, you can check out the article by underwater volcanoes.
