1:09 p.m. Eastern, June 10
It was a very busy week, and I missed the news (Spanish) that CENAPRED had lowered the alert at Popocatépetl back to 2.
Popo is still at yellow alert, and they are still monitoring it closely. According to the above news article, going back to phase 2 basically means that the 1500 marine, Army and Federal Police personnel that were deployed back in May can now return to regular duty.
10:34 a.m. Eastern, June 2
Don Goyo is behaving himself lately, but in yesterday’s bulletin CENAPRED shared three images of the crater taken during a May 28th overflight. They said about these:
On May 28 a reconnaissance flight of the volcano´s crater was carried out, in which the presence of a dome was corroborated. It is mostly covered by rock and ash fragments produced by the explosions of the few last weeks, with a small crater on its surface produced by the explosion of May 15th. Additionally, the scars left on the snow by the impact of ballistic incandescent fragments can be seen (see image), (see image), (see image).
Also, there was some activity on the PPIG webicorder on May 30th, so I started the time-lapse video capture program. Popo didn’t pop any more than usual, but lenticular clouds kept forming partially on the summit all afternoon, and around sunset, all but one big thunderstorm behind the volcano and to the left cleared, and spectacular lenticular clouds formed at the summit. My video process isn’t perfect, but I did get the basic images:
Those are stars moving across the night sky at the end, by the way. I’m not sure of the constellation, perhaps Cassiopea?
3:45 p.m. Eastern, May 27
After this post, I will take a bit of a break, unless something drastic happens at Don Goyo – and it could at any time, although this morning’s CENAPRED bulletin shows the volcano is staying in its recent pattern, with less explosiveness perhaps in the last 24 hours (it’s still having harmonic tremor).
An article today online in Ladobe (Spanish) reports that Director Aurelio Fernandez of CUPREDER (again, Spanish) reportedly said (per Google’s translation and mine) that the activity recorded by the Popocatepetl in recent years is negligible compared to the potential of the colossus, which, he said, ranks as one of the most explosive in the Americas. In comparing eruptions over the last 1000-2000 years, this volcano’s activity in the last 20 years hasn’t even left a layer in the subsurface; in 100 years, it hasn’t marked the surface.
CUPREDER, by the way, is a regional disaster prevention center based at the University of Puebla, while CENAPRED works at the national level. CENAPRED does the monitoring at the Colossus of Puebla, along with two institutes at Mexico’s National University and with collaboration from the USGS.
Other CUPREDER academics, including Vincent Nolasco, are quoted in the Ladobe article as saying that Santiago Xalitzintla and San Nicolas de los Ranchos are at risk of lahars. Xalitzintla, he noted, experienced one in June 1997, and there was another one in the same zone on January 22, 2001.
I don’t envy CENAPRED volcanologists and emergency professionals their job. Popocatépetl is going to be socked in with clouds and lahar detection will be difficult without good visibility.
Fortunately, the alert level at Don Goyo is still yellow, albeit at the highest sublevel of 3. The volcano is restless, though, and as noted in Part 1 of Operative Plan Popocatépetl, it can be quite dangerous if things escalate.
According to Google’s translation with some cleanup by me, the Plan’s background section notes:
From the beginning of our era [after the conquest, I think…BJD], its eruption of lava has stopped as its main vent is completely blocked. In the course of centuries it has only had strong eruptions through internal cracks, which have cast moderate-sized stones, ash and large gaseous fumes huge distances. It did have three side vents south and southeast, but after the eruptions in 1919 there have been only two.
The main map shows three different areas: 1, 2 and 3, according to their danger. Colors of these areas are intended to show that the greatest risk is to the top of the volcano. Each zone includes all hazards associated respectively volcanic eruptions large, medium and small.
Area 1, being the closest to the top of the volcano, is what poses a greater danger because it is the eruptions most commonly affected, regardless of their magnitude. This area encloses hazards such as volcanic material flows at high temperatures that descend the volcano at extremely high speeds (100-400 km/hr) [those hot puffy death clouds known as pyroclastic flows…BJD] and lahars that move following existing channels at lower speeds.
Area 2 has less risk than area 1 in that it is affected by eruptions less frequently. However, eruptions that have reached this area produce a degree of danger similar to Area 1. The frequency of occurrence of volcanic events affecting this area is 10 times every 15,000 years on average.
Area 3 covers an area that has been affected in the past by extraordinarily big eruptions. Eruptions of such magnitude are relatively rare, so that the risk within these areas is lower in relation to that areas 1 and 2, closer to the volcano. The hazards in area 3, however, are essentially the same as those of the other areas. In the past 40,000 years there have been 10 eruptions of this type.
Zone 1. This could be affected by the fall of significant amounts of volcanic sand [they didn’t say “ceniza” so I’m not translating it as “ash” … BJD] and pumice, whose accumulations reach several centimeters in the case of small eruptions or several meters, with blocks of up to 30 cm [about 1 foot … BJD], in very large eruptions.
Zone 2. This could be affected by moderate fall of volcanic sand and pumice, whose thickness can vary from a minimum of 1 mm (light covering of fine powder) in small eruptions to up to a meter in large eruptions.
Zone 3. This would be less affected by falling volcanic sand or pumice. There would not be fall during small eruptions but it could accumulate tens of centimeters during very large eruptions.
There is a remote possibility that a part of Popocatepetl could collapse, causing a giant landslide.
This would move at high speed (about 100 km/hour) [a little over 60 mph – yes, this has happened there…BJD] up to a maximum distance of approximately 80 miles, destroying everything in its path.
Over the past 40,000 years, 2 large landslides occurred south of the volcano, covering large areas; if another event of this kind happened, it probably also would head south. Generally large deformations that can be observed precede these collapses.
A large eruption or collapse would be accompanied by giant mudflows and powerful floods. These would travel distances of tens of kilometers through the canyons down Popocatépetl.
Well, that last is the absolutely worst-case scenario and it’s not unlike that posed, for example, by Mount Rainier in Washington State. Extremely unlikely but not impossible, in other words.
They do have a graph in the plan showing the likelihood of various scenarios. From what I’ve read – and keep in mind that I’m not particularly well read, nor an expert – my understanding is that flank collapse can happen without warning, because it’s just basically ground failure. There don’t have to be magma movements or earthquakes to set it off (though such things possibly could if the wall was weak enough), so movement sensors might not pick up any precursors.
Perhaps that as well as the extreme unlikeliness of such an event in our lifetimes is why they didn’t include that possibility in their graph. They’ve got most of the others covered:
All you need to know, if Spanish is not your thing, is that they estimate that chances are 70% to 90% that Popo will continue having small eruptions; 10% to 25% that it will increase to a moderate intensity; and 2% to 5% that it could go plinian (like Mount St. Helens in May 1980, if not necessarily at the same intensity).
So, yeah, I’m glad I don’t have CENAPRED’s job now that the volcano will often be shrouded in clouds this summer. However, last year it just kept cooking along and finally settled down a bit in the fall. Hopefully, something similar will happen this year.
I’ll post again if and when something changes, up the scale or, preferably, back down to a lower alert level when live-blogging really won’t matter much.
3:15 p.m. Eastern, May 26
As mentioned in the update today (which has a couple of good images of Popo), I had to skip a few days but Popocatépetl didn’t – CENAPRED has noted sizable amounts of spasmodic and harmonic tremor, and the volcano continues to have intermittent small to moderate explosions.
Here is one of the smaller explosions, seen from two different cams (Tlamacas on the left and Alztomoni on the right):
Here is a video of the activity from May 18 through May 25, as seen from the Tlamacas cam, sequential in roughly 2-minute captures except for 81 bad segments, some duplicates and a few out-of-sequence images that I apologize for and will try to avoid on future videos:
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