27 October 2011
Last week I talked about “translating” eyewitness accounts of the 1902 eruption of Santa Maria in Guatemala. As all of you probably know by now, the Santiaguito lava dome complex started growing in the 1902 eruption crater in 1922. At first there was just one dome (which was called Santiaguito then, and which we now call Caliente). There isn’t much in the literature about the early days of the dome growth; most of the accounts we have about the area come from German explorers Karl Sapper (an ethnographer and linguist) and Franz Termer (a professor of geography and anthropology).
One especially thorough account is their record of the dome collapse that occurred at Santiaguito on Nov. 2, 1929. The collapse was estimated to be about 3 million cubic meters in volume; to put that in perspective, the collapse of Mount St. Helens in 1980 removed about 3 billion cubic meters of material from the volcano, and the 1996 “Boxing Day Collapse” at Soufriere Hills was around 50 million cubic meters. So, Santiaguito’s collapse was fairly small as collapses go – but it still had devastating effects. Many of the fincas (coffee plantations) in the river valleys below the dome were destroyed, and hundreds (possibly thousands) of people were killed. (The number might have been in the hundreds, but a festival for All Saints’ Day was going on at the time, and many people were visiting the fincas from other towns, and sadly were caught in the destruction.)
Sapper & Termer (1930) published an account of the collapse, incorporating interviews and newspaper articles from people who escaped the effects of the collapse and those who visited the area afterward. Many of these people may have remembered the 1902 eruption, but probably never had a chance to talk to a scientist and pick up on the technical terms for what they saw in 1929 – so, like the 1902 eruption accounts, the descriptions of the event contain a lot of interesting word choices. (Note: The Sapper & Termer account I have was translated from the original German article. The translation is excellent, but there are occasionally quirks of grammar that are probably related to the difference between German and English sentence structure. I’ll leave them as they are, since I don’t speak German and can’t comment on the accuracy of the translation.)
*Note: I have photos of the aftermath of the collapse, but I will have to check with their original owner to see if I can post them here. For the moment, we’ll have to stick with text.
Here is an account of the collapse from a letter written to the authors:
Mr. Koeper Jr. reported later by letter that according to accounts of Topke…the western part of the cone for several weeks before the eruption had kept on glowing. However, in the night of the catastrophe it had been fiery red and jets of fire (Feuergarben) had shot up into the night sky with colossal force. Along with a terrible deafening roar part of the south side had broken away and the whole mass of glowing mud or ooze then had come down into the Tambor River.
This describes a dome that either had active lava flows or hot rockfalls (which glow at night). It sounds like the collapse was initiated by an explosive eruption; the “glowing mud or ooze” was probably the incandescent rock of the dome’s interior collapsing into the Tambor River (a major drainage channel below the domes).
A man named Isauro Mendez of Las Animas recounts a visit to the devastated area following the collapse:
When we came through the plantation of El Patronchinio we observed lamentable scenes, arms that stuck up out of the sea of ‘lava’, legs which stuck out from under the ruins of the house and the like. The manor house was completely destroyed. In many places we had to lay down boards in order not to burn our feet and protect ourselves against the hot ‘streams of lava’ over which we had to pass.”
The word ‘lava’ is often used in these accounts, and likely isn’t describing actual lava flows, but rather the hot ash and rocks of the collapsed dome. Many of the rocks seem to have been initially incandescent, which may have been why people were calling them lava, and the ash (and maybe lahars?) which overran the plantations probably retained a lot of heat. (Pyroclastic deposits from the collapse of Mount St. Helens measured anywhere from 100 to 850 C a few days afterward, so ashy deposits from Santiaguito’s collapse would have been extremely hot immediately after.)
Here is a more complete account from the owner of the Las Animas plantation, Enrique Perret:
He reported in the El Imparcial of Nov. 6 that he had withdrawn to his bedroom when suddenly a glowing hot breath passed over his entire estate. One heard on the roof of the house and the trees the impact of ashes and sand while at the same time the strong detonation shook the surroundings…Mr. Perret went out and saw the tremendous spectacle that was offered. A reddish light came from the volcano. Great glowing masses were hurled into the heights and there exploded. A strong odor of chlorine filled the surroundings (improbable but perhaps hydrochloric acid? – the authors). The window panes were smashed but not by being hit with ashes and sand but rather on the account of the high temperature of that accursed breath. Mr. Perret ran to the bell and began to toll it violently so that the workers that were still alive would gather. From the first moment on many had died from burns due to the glowing hot breath or on account of suffocation.
This account seems consistent with the effects of a pyroclastic surge – a dilute, hot current of ash and gas that can form from the overriding ash cloud of a pyroclastic flow. The surge may not be powerful enough to knock down buildings, but it can certainly bring temperatures hot enough to cause burns and suffocation.
The owner of the El Patroncinio plantation, Valero Pujol, tried to cross the Concepcion River:
I saw that the river had strongly swollen and was red, so that its banks were lit up dully. The cause was ‘lava’ and the glowing residue that it was carrying along with it. It had almost reached the bridge, so that the iron supports were already bent still the supporting beams fortunately were still not reached by the hellish waters. Accompanied by my foreman I now turned toward the Rio San Jeronimo, a smaller river which empties into the Rio Concepcion. The foreman ran ahead and soon returned to inform me that the river had reversed its current, that is to say running backwards – undoubtedly because its water swollen by the lava was held back from the Rio Concepcion.
It sounds here like collapse deposits were channeled by the rivers below the domes, and that the ‘lava’ was probably incandescent dome rock rather than actual lava flows. (The lava flows on Santiaguito are dacitic, and don’t move fast enough to flow down river channels in the short timescale being described here.)
A scientist named Dr. Wilhelm Seier managed to make the trek to see the deposits a day or two after the night of the collapse:
There is no lava. The Tambor and also several tributaries have already eroded deep into the debris. At these points one can get a glimpse of the interior. Below lies an ash-mud layer with numerous small and also large stones. Its thickness reached 2 to 3 meters in places. Above lay up to 2 meters of ash without stones and finally a thin layer of fallen ash. The inside of the mass was still after 4 weeks tremendously hot. The ash was looser and had only a weak surficial crust. Even going cautiously one frequently sank in. As I once sank up to the knee in the ash, I had to spring out quickly. I burned my leather spats and had to remove them to get at the penetrating hot ash which already had set fire to my socks…[Note: another translation might be “I tore my leather spats off and removed the hot ash that had penetrated from above, which already was burning [my leg] through the socks like fire”]…While the mantle of the dome in October was everywhere intact, a deep notch was evident on the SW slope since Nov. 3…from the area of the new debris one sees at night a red glow in the cracks.
Clarification at last! This account makes it pretty clear that the deposits are mainly ash, mud and rocks – the results of a pyroclastic density current rather than lava flows. (Incidentally, while it can’t have been pleasant to walk on ash hot enough to burn things, the “already set fire to my socks” comment – and the matter-of-fact way he reports it – is kind of funny. [Note: Seems like the droll tone I perceived may have been a result of the nuances of translation, which was since corrected by a native German speaker for me.])
One curious account was by Carlos Wyld Ospina, editor of El Imparcial newspaper, who makes an interesting claim:
The capital press has attributed the present eruption to the edifice called Volcancito, and, lately, Santiago. There have been those who argue that there are, in effect, two separate volcanoes. But this, for those knowledgeable about the area and for those who have studied the observed extrusions, is a mistake born of appearances. The volcano is simply a pile of rocks thrown from the crater of Santa Maria, which is known to erupt…the ‘little volcano’ has been formed precisely at the edge of the crater, its position indicating its origin…[Ospina then describes at length the appearance of a short-lived spine on the dome, and states that because it collapsed, it proves that the dome could be built up by agglomeration of Santa Maria’s eruptions]…It may therefore be said with certainty almost complete, the volcano does not exist as such and that the only real volcano was and is the Santa Maria.
Ospina seems for some reason to be convinced that Santiaguito itself could not have been the source of the collapse – that Santa Maria must have erupted and that Santiaguito is simply a pile of rocks erupted from the crater of Santa Maria. This is actually half-correct – the original dome of Santiaguito did come from the crater, but was also perfectly capable of erupting all on its own. This being early in the study of volcanoes (and Opsina, presumably, not being a geologist), this is not too egregious a mistake to make. It’s kind of funny that he uses this article as a soapbox for saying that obviously everyone else must be wrong about it, though.
Sapper, K., and F. Termer, Der Ausbruch des Vulkans Santa María in Guatemala vom 2-4 November 1929, Zeitschrift fur Vulkanologie, 13, 73, 1930. (Translated by Bill Rose and Arnold Weinkauf)
Ospina, C.W., Cuatro Horas de Marha por el Desierto de Arena a Corta Distancia del Crater del Santa Maria, An. Soc. Geogr. Historia de Guatemala, 7, 1:68-79, 1930.