Airports temporarily closed, flights cancelled, face-to-face classes suspended at nearby schools…
The Popocatépetl volcano in Mexico has been attracting all eyes for several days due to the impressive images it offers in the form of expulsions of incandescent material and explosions, as well as large exhalations of smoke and ash that reached nearby towns and activated emergency protocols at the authorities.
Popocatépetl is active. However, this is not new since the “smoking mountain”—in the Nahuatl language—restarted its activity at the end of 1994. In fact, this is the sixth time since the year 2000 that the yellow phase 3 precautionary alert has been issued which is valid today.
Thus, scientists call for calm and to follow the official recommendations based on the 24-hour monitoring of the volcano, also known as “el Popo” or “don Goyo”.
“The current behavior of Popocatépetl is slightly more intense than it has been on previous occasions, but nothing disproportionately different. It is within the behavior that we have observed since it was activated ”, emphasizes Juan Manuel Espindola, researcher at the Institute of Geophysics of the National Autonomous University of Mexico (UNAM).
Based on previous experiences, the expert predicts that the current activity of the volcano would continue in the form of sporadic explosions, but that it could gradually decrease in intensity and “decay” over the next few weeks.
“It is like the equivalent of a patient who is in intensive care and is being watched. It may be that he remains stable, that he goes into a dangerous phase or that he is definitely discharged ”, he compares.
“Now we are in the observation phase and there is no information that it is moving to a more dangerous phase. there is no evidence of that“, he emphasizes.
Together with Espíndola, on BBC Mundo we tell you seven facts about Popocatépetl, one of the most active volcanoes in Mexico and with which the inhabitants of this area have lived for thousands of years.
1. One of the most dangerous in the world
Popocatépetl is considered one of the most dangerous volcanoes on the planet due to its proximity to densely populated areas.
The “Popo” is located in the center of Mexico, between the states of Morelos, Puebla and the State of Mexico, and less than 100 km from the capital, Mexico City.
Therefore, it is estimated that a large eruption could affect about 25 million people who live within a radius of 100 km around the volcano, where there are schools, hospitals and airports. The town of Santiago Xalitzintla is the closest as it is only 12 km from the crater.
In addition, Popocatépetl is part of the so-called Pacific Ring of Firewhich borders said ocean with a length of about 40,000 km.
This ring is considered the largest and most active seismic region, and 75% of the world’s volcanoes are concentrated in it and the vast majority of earthquakes have their epicenter.
2. Formed in the crater of other volcanoes that collapsed
In fact, Popocatépetl is not the only volcano that is part of the so-called Sierra Nevada of Mexico.
Next to it there are other large volcanoes such as the iztaccihuatlalso known as “The sleeping woman” and with whom, according to a popular legend, eternal love was sworn.
What is proven is that, in its more than half a million years in which it has been active, it has presented various stages of growth that formed at least three other volcanoes before it.
These were destroyed by huge eruptions: Nexpayantla more than 400,000 years ago, Ventorrillo about 23,000 years ago, and El Fraile about 14,500 years ago. The modern cone of Popocatépetl is formed on the remains of these volcanoes.
3. “He doesn’t sleep” since 1994
Although many believe that it is now that Popocatépetl has erupted, the truth is that the images it leaves these days are only one episode within a period or eruptive event that began at the end of 1994.
Before that, “don Goyo” had been “asleep” for some seven decades since his last activity in the 1920s.
This has led some experts to point to a kind of pattern of behavior that the volcano could reactivate approximately every 70 yearsthen be active for a while and go back to sleep.
According to Espíndola, “the problem is that the life of volcanoes is very long and this needs to be studied in greater detail for a long period of time to see if this pattern is verified.”
“And, in the case of volcanoes, this behavior is vague, so the current data they do not allow us to reach with certainty that conclusion that it will be activated every 70 years“, he disagrees.
4. Stratovolcano
For all this, the “Popo” is classified as a stratovolcano. In other words, it is made up of different layers that have been formed in each of the many phases of its long eruptive life in thousands of years.
“These layers are of different types and could have been formed by lava flows, pyroclastic material…”, explains Espíndola.
“This is how the volcanic edifice is formed and that is why stratovolcanoes are so tall and big: because they have been built in different stages of massive emissions”, he adds.
With a crater 900 m in diameter and an altitude of 5,452 m above sea level, Popocatépetl is the highest volcano in Mexico after the peak of Orizaba or Citlaltepetl.
5. Among the 5 that emit the most gases in the world
A 2013 UNAM investigation placed Popocatépetl among the five volcanoes in the world that emit the most gases into the atmosphere.
That study estimated 30 megatons of gases those expelled by “don Goyo” between 1994 and 2008. Its most important emissions are sulfur and carbon dioxide, as well as the water vapor itself.
Far from what it may seem at first glance, experts say that the efficient expulsion of gases helps to avoid other more serious problems and that their ventilation helps in some way to “clean” or release the internal ducts of the volcano.
“This is so as long as there is no more material coming from the interior of the volcano, because that would be noticeable in a more intense seismicity,” Espíndola qualifies. “But so far none of that has been noticed”.
6. An enigma inside
The truth is that the interior of Popocatépetl, as with all volcanoes, is quite an enigma.
Its large size and the difficulties in access due to being active make its internal structure very little known, since the existing models to monitor it are based, for example, on in factors like seismicity.
Espíndola explains that the guide that one has to know something more indirectly about this subject is thanks to the location of the earthquakes, which allows us to assume the area where the volcanic conduit is.
“But there is no volcano where you can have exact information. Even in the most studied, there is only some data on the conduits of the volcanic edifice, but the magma comes from many km deep underground… so there is no direct information, but rather the inference that some data such as earthquakes provide us” , assures.
7. The most guarded in Mexico
For all these reasons, it is not surprising that Popocatépetl is the most monitored volcano in Mexico, with a team of 13 scientists from different specialties They monitor your activity day and night.
Currently, a group of cameras, sonic sensors, seismic and meteorological stations help monitor its activity 24 hours a day by sending data to a control center located in the south of Mexico City.
“Specialists who study different areas such as seismicity, emissions, geochemistry… participate in this committee, and all this information is provided to the authorities, who have taken the issue seriously and are periodically informing the population of what they have to do. ”, says Espindola.
“And that is the important thing: to stay informed”, tops off
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See original article on BBC