2023-05-19 05:18:02
MEXICO CITY (AP) — Every time Popocatépetl’s summit spews fire or stronger than normal puffs of ash, as it did this week, it does so under the watchful eye of a dozen scientists. Nothing goes unnoticed because millions of people, and even air traffic, may be affected if it erupts: eleven towns closed their schools this week due to ash accumulated on streets and cars.
For almost 25 years the “smoking mountain”, as the pre-Hispanic peoples called it, has been the most monitored volcano in Mexico: seven cameras -one of them thermal-, 12 seismographs, six stations to measure deformations on its slopes, two sensors Infrasonic and seven weather stations send data 24 hours a day, 365 days a year to a control center located 80 kilometers south of Mexico City.
There, 13 scientists from different specialties cover various shifts in a room covered by screens, a kind of intensive care unit where each tremor is recorded in real time, each exhalation of the “Popo”, as the Mexicans call that 5,426-meter-high mountain. height that arose in the crater of other volcanoes and whose current form dates back more than 20,000 years.
The reason for so much monitoring? Within a radius of 100 kilometers live 25 million people, there are hundreds of schools, hospitals, homes and five airports with constant national and international traffic. Everyone might be affected by a rash.
Paulino Alonso, one of the managers of the Natural Phenomena Monitoring Laboratory of the National Center for Disaster Prevention of Mexico (CENAPRED), checks all the screens when he starts his shift, checks the seismicity of the country, the volcano and the capital, as well as like weather forecasts and fumaroles over the crater.
Ash clouds deserve special attention. As the technician explained, they are more or less large and almost constant, because since 1994 the volcano has not slept.
A satellite map marks those clouds and a computer forecasts the movements they will make. Its main danger is respiratory problems in the population and its effects on planes, because the ash can affect visibility and act like “sandpaper” on its fuselage and wings.
Unlike earthquakes, volcanoes are more predictable and, although nature can always give surprises, there are warning signs: an increase in explosions of ash and pyroclastic material, deformation of the slopes, more tremors or an increase in levels of certain gases or chemicals in the springs in the area.
To explain in a simple way to the population the level of danger at all times and the precautions to be taken, CENAPRED designed the “volcanic traffic light”: green means calm; yellow, alert; red, danger. For years it has oscillated between various levels within yellow, which indicates that you have to be prepared, but without alarm.
The room also monitors other natural phenomena such as earthquakes —specifically the alert system in the main cities—, hurricanes and even the intensity of the Sun’s cosmic rays. “If there is a major explosion (in the Sun) they might communications and the transmission of electrical energy may be affected”, indicates Alonso.
The day is calm, but suddenly a chord sounds. Then a beep that repeats every second. A station has detected a strong earthquake and the computer is waiting for another to confirm before alerting to avoid false alarms.
It is a recording of what happened during the earthquake on September 7, 2017. On the screen you can see how the earthquake of that day —graphed by colored waves— advances from the south to the center of the country. A purple wave arrives earlier in the capital; is the one that sets off the alarm. Seconds later the yellow ones arrive, representing danger.
If the epicenter is not on the coast but in the center of the country, the authorities’ room for maneuver is much less, because it can start to shake in the capital without sounding the alarm, as happened in another earthquake, the one on 19 September 2017, in which approximately half a thousand people died.
After 48 hours, the team of 13 scientists rotates and the surveillance routine begins once more.
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