Popocatépetl, May 21 (2240 UTC)


Yellow, Phase 3.

Update, May 21, 2023, 3:41 p.m., Pacific: Just got back from an unavoidable chore that kept me offline, though I wondered if they would raise the alert level.

They did, to Phase 3.


CENAPRED’s website linked above appears to be getting much traffic, so here is the relevant part of their current report, via browser translation (the original page, if you can get there, has much more information, graphs, etc.):

May 21, 12:00 pm (May 21, 18:00 GMT)

At the 81st meeting of the Popocatépetl Volcano Scientific Advisory Committee held yesterday, May 20, and based on the analysis of the information available in recent days, It was recommended to change the phase of the Volcanic Alert Traffic Light from Yellow phase 2 to Yellow phase 3, which constitutes a preventive measure against the observed changes.

In the last 24 hours, through the monitoring systems of the Popocatépetl volcano, 31 exhalations accompanied by water vapor, volcanic gases and ash were detected. Additionally, 1,136 minutes of high-frequency tremors of low to great amplitude were recorded, associated with the continuous emission of gas, water vapor, and ash, as well as on occasions of expulsion of incandescent material at a short distance from the volcano (video 1 ) , (video 2) , (video 3) . Also, four minor explosions were registered yesterday at 10:47, 12:47, 21:36, 22:38 and 23:34 local time and two moderate explosions yesterday at 14:54 and 22:53 local time (image 1) , (video 4) .

CENACOM (National Center for Communication and Civil Protection Operations) reported yesterday ash fall in the municipalities of Juchitepec, Amecameca, Cocotitlán, Valle de Chalco, Ixtapaluca, La Paz, Nezahualcóyotl, Tlalmanalco and Chalco in the State of Mexico . As well as in Huejotzingo, Nealtican, Chignahuapan, Puebla Capital, San Martín Texmelucan and San Felipe Teotlalcingo, municipalities of Puebla. As of today, there is a report in the municipalities of San Andrés Cholula, San Pedro Cholula, Cuautlancingo, Amozoc, Puebla Capital, Zacatlán, Tetela de Ocampo and Chignahuapan belonging to Puebla.

The explosions that occur in Popocatépetl or in any active volcano are accompanied by seismic and sound signals (image 2)., the latter recorded by means of pressure detectors or with microphones. It is possible to hear them with different levels of intensity, depending on atmospheric factors at the time of the events or the morphological conditions of the crater. This is a normal phenomenon and is not necessarily an indication of increased volcanic activity. It should be noted that in the current condition of Popocatépetl, characterized by the formation of small lava domes, and their subsequent destruction by explosions, mainly of smaller to moderate size, it is likely that in the coming days or weeks the population near the volcano will perceive these audible phases.

At the time of this report, there is partial visibility towards the volcano due to the weather conditions in the area. However, constant emission of water vapor, volcanic gases and slight amounts of ash has been observed in an easterly (E) direction (video 5) .

CENAPRED emphatically reiterates the recommendation NOT TO ASCEND to the crater of the volcano, since there is the possibility of explosions occurring, as has been seen on several occasions in the past, involving the emission of incandescent fragments (image 3 ) . Therefore, it is insisted on respecting the exclusion radius of 12 km. Likewise, in case of heavy rains, move away from the bottom of ravines due to the danger of mud and debris flows.

Consistent with what was expressed by the National Civil Protection Coordination in the press conference held today, May 21, at CENAPRED, the Popocatépetl Volcanic Alert Traffic Light is in YELLOW PHASE 3.

The recommendations for the population in light of this activity are: Ignore rumors and be attentive to the information issued by the National Civil Protection Coordination through its official channels and accounts http://www.gob.mx/cenapred and @CNPC_MX

Given the probable fall of ash, it is recommended:

1. Cover nose and mouth with a handkerchief or face mask.
2. Clean eyes and throat with pure water.
3. Wear frame lenses and avoid contacts to reduce eye irritation.
4. Close windows or cover them and stay indoors as much as possible.

The scenarios foreseen for this phase are:

1. That the explosive activity continues on a low to intermediate scale.

2. Light to moderate ash rains in nearby towns.

3. Possibility of pyroclastic flows and short-range mudflows.


Special emphasis is placed on the following recommendations:

1. Continue with the 12 km safety radius, so staying in that area is not allowed.

2. Control traffic between Santiago Xalitzintla and San Pedro Nexapa, via Paso de Cortés.

3. To the Civil Protection authorities, maintain their preventive procedures, in accordance with their operational plans.

4. The population is recommended to pay attention to the notices of the local authorities and is urged not to approach the volcano, much less the crater.

The monitoring of the Popocatépetl volcano is carried out continuously 24 hours a day. Any change in activity will be reported in a timely manner. The level of the Volcanic Alert Traffic Light will depend on the evolution of the volcano’s activity.

Volcano alert traffic light

[Wind] direction

Sulfur dioxide emission
3400.0 Tons per day
Last reading: July 22, 2020
Maximum registered value:
70200.0 [t/day]
Maximum (Dec/2000)

Popocatepetl seismograms
Atlixco Station
Tetexcaloc Station

At the time this change was announced, volcanologist Dr. Carlos Valdes, an expert on Don Goyo, shared this:


That was four hours ago.

About an hour ago, SkyAlert tweeted some MODIS imagery of Popocatépetl’s summit dome building:


That is VERY hot. [LAYPERSON SPECULATION]Of course, it would be. Probably what is causing this increased activity is the arrival of an injection of fresh magma from greater depths than Popo’s usual reservoir. Besides being hotter, it probably also contains lots more gas.

You see, Popcatépetl, like Colima and Indonesia’s Merapi, among others, has an open conduit (Chaussard et al.)

That’s good because it allows gases to exsolve from magma and escape before they accumulate enough to cause a big explosive eruption.

This also slows down the speed at which the magma rises, and because this subduction-zone magma is so sticky, it just oozes out of the vent and piles up into a dome.

That has been Popo’s M.O. for decades (it woke up in 1994).

The plumbing system is very complicated, of course, but as at all volcanoes, very hot “primitive” magma can and does move up sometimes. While the heat and gas make this dome construction/destruction thing faster, louder, and more intense, the magma chemistry typically doesn’t change (as I understand it).

So what we’re looking at is most likely the same old Colossus of Puebla; it has just gotten a ‘hormone shot.’

I think it’s actually good that the volcano is blowing off so much stuff. Things tend to get plinian when there is no way to let off steam (and gas and ash, etc.)

It’s tough on the neighbors, but with volcanoes, “quiet” is sometimes a very bad (and short-lived) thing.

There is no guarantee that Popo will not escalate. It has done so in the past (a couple thousand years ago, I think, or thereabouts).

When these injections of magma come up, they can rise so fast and be so large in volume that the volcano’s open conduit isn’t big enough to release pressure. Per the sources quoted in my Merapi chapter, that’s what happened at that Decade Volcano in 2010.

Popocatépetl is not Merapi, and it will do its own thing. It’s just as likely to simply carry on this way for a while and then calm down. Volcanoes are a little like cats that way — it’s sometimes easier to explain why they did something than to predict what they will do next.

I wish there weren’t tens of millions of people living around it — but because there are, the best minds on the planet have been planning a long time for this and are now following it closely. Listen to them and do what they say — and also try to be a helper whenever you can.[/LAYPERSON SPECULATION]

And don’t forget the pets need protection, too!


Update, May 21, 8:07 a.m., Pacific: Ashfall update from SkyAlert:


This nice view of the big picture was tweeted about half an hour ago.

Up close, the column looks scary, but from a distance, this is a strombolian, not plinian, column:


Here is the latest on that news conference later this morning:


Update, May 21, 7:33 a.m., Pacific: The governor of Puebla this morning. Per Google translation of the tweet text, “He specified that the volcanic traffic light remains in Amarillo Phase 2; there are no indications of a possible eruption.

📰 He called on the population to remain calm and inform themselves through official channels.”


Update, May 21, 2023, 7:10 a.m., Pacific: Actually the cams have cleared. This is a screenshot from Tlamacas (have the sound on, too):

[LAYPERSON SPECULATION]This seems like high-end strombolian activity.[/LAYPERSON SPECULATION]


Update, May 21, 2023, 6:35 a.m., Pacific: I don’t think there will be a “Good morning, Popocatépetl!” postcard-perfect image possible this morning, because of cloudiness.

However, shortly before midnight last night, it was roaring in a strombolian fashion (none of this approaches plinian-style activity, as far as this layperson knows):


The current VAAC advisory is impressive, too — in terms of Don Goyo’s past advisories, it is a little larger:

FVXX20 KNES 211009
DTG: 20230521/1009Z
PSN: N1901 W09837
SUMMIT ELEV: 17693 FT (5393 M)
ADVISORY NR: 2023/610
OBS VA DTG: 21/0941Z
OBS VA CLD: SFC/FL320 N2004 W09729 – N1942 W09451
– N1843 W09541 – N1826 W09711 – N1859 W09839 –
N1904 W09840 – N2004 W09729 MOV E 20KT
FCST VA CLD +6HR: 21/1530Z SFC/FL320 N2103 W09555
– N1859 W09448 – N1831 W09705 – N1857 W09838 –
N1904 W09841 – N2103 W09555
FCST VA CLD +12HR: 21/2130Z SFC/FL320 N2120
W09519 – N1844 W09441 – N1856 W09839 – N1904
W09840 – N2120 W09519
FCST VA CLD +18HR: 22/0330Z SFC/FL320 N2050
W09453 – N1903 W09416 – N1855 W09838 – N1904
W09840 – N2050 W09453

Around midnight, Civil Protection Puebla tweeted, that city’s airport closed; it’s current status is unclear to me.

About an hour ago, Carlos Martin Huerta shared these morning views near his place, in Puebla:



Despite all this, the alert is still YELLOW, PHASE 2 at the CENAPRED page, which is nice to know.

Yesterday, the scientific committee announced they will hold a press conference this morning.

Meanwhile, some good vibes and coffee:


Ojalá que sí.

Earlier posts:

Featured image Popocatépetl in early 2019, by Puebla Civil Protection (Spanish)

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