Located in the Eastern Cordillera (Real), in the plain of Limpiopungo 35 km northeast of Latacunga and 45 kilometers southeast of Quito, Cotopaxi is one of the most closely watched volcanoes of Ecuador; a large part of the available resources is devoted to monitoring it. In fact, the first permanent seismic station dedicated to monitoring a volcano in South America was installed on Cotopaxi, in 1976. Since then, the network monitoring the volcano has grown steadily to the current configuration, which ensures allround monitoring of this dangerous volcano.
Since April/Mai this year there have been reports, from people walking or climbing Cotopaxi, of strange sulforous odors and when measurements had been carried out, indeed the results were hightened output of SO2. There was a large increase in earthquakes (including harmonic tremors) and IGPEN reported slight deformation of the edifice, suggesting an intrusion of magma under the volcano. Last Thursday, 13 August, seismic activity increased considerably and from the early hours of Friday 14th through the day 6 ashy phreatic explosions took place (04:02, 4:07, 10:25, 13:45, 14:29, 16:32) the first and biggest with an ash plume of 12 km. It has also been said, but I was not sure about the translation, that a pyroclastic flow has occured, possibly on Saturday.
The first reaction of the government scientists was to assure the public that the 5,987 m (19,600-foot) high, snow-capped volcano did not seem to be on the verge of a major eruption. Authorities nevertheless restricted access to the park that surrounds Cotopaxi and suspended ascents of the peak, which is popular with mountaineers.
Although Ecuador’s top disaster official, Maria del Pilar Cornejo, said on Friday a Yellow alert had been issued, which means that no evacuations were needed, on Saturday was ordered the evacuation of villagers who live in one of the pathways of potential lahars. This was a precautionary measure and had nothing to do with more severe activity of the volcano.
The state of emergency was declared on Saturday for the three provinces concerned, Pichincha, Cotopaxi and Napo.
Looking at the photo (above right) one does not think of a well organised and prepared evacuation. However, reading the alerts, newspaper and internet articles on how to react and how to prepare I have got the impression that scientists, government and local authorities are doing a very good job on informing everyone. It is now up to the people themselves to listen and look for, and actually heed the advice and orders given by experts.
The latest daily report (No. 74, 16 Aug. 2015) states:
State of volcano: Active erupting
Internal Activity Level: High
Surface activity: Moderate
Seismicity: In the last 24 hours 120 events of long period (LP), 2 hybrid (HB), 1 event volcano tectonic (VT) and 9 episodes of tremor were recorded broadcast.
Gases: From 07h00 to 17h00 yesterday through DOAS instruments an average of 16677 t / d of SO2 was recorded from 32 valid measures. Satellite measurements (OMI) report 6400 tons.
Observations, emissions and ash: Working groups of the Geophysical Institute reported the presence of ash in the area of Cotopaxi Park this is a fine, black and sand body as film, this is related to the activity yesterday. Today no ashfall is reported and little sulfur smell is perceived. They also reported that from the west of the volcano remobilization of volcanic material (ash) deposited on the flanks, due to strong winds (up to 3300m) is observed.
Rain: A rain gauge located in the north-eastern flank collected 18 mm of rain in the volcano area
Note: Today three teams of the Geophysical Institute conducted the collection and identification of ash deposits in addition to maintenance and repair of monitoring stations that were affected by the ash.
The volcano crater is oval with a diameter of 800x600m and a depth of 200 m from rim to bottom. This volcano appeared in the middle Pleistocene between one million and 200 000 years ago on even older volcanic layers.
The small hill Morurco or Guagua Cotopaxi that is a bit further south is a remnant of the old Cotopaxi caldera of more violently active times than currently. By the end of the Pleistocene, the older volcano resumed its activity and built the present volcano. The explosiveness of eruptions and the large amount of incandescent material have generated numerous lahars that have reached the Pacific Ocean; these flows have in historic times traveled twelve times along the course of Rio Cutuchi, three times the Pita River and four times the Rio Napo.
Cotopaxi is considered one of the world’s most dangerous volcanoes.
The greatest risk from Cotopaxi are its Lahars, owing to the glacier cap and to its ca 3000m high (above ground) steep sided cone shape. Moreover, the beds of the three main rivers draining the volcano to the SW, NW and E are going constantly down on a more ore less steep gradient, either to the Pacific shore in the west or reaching the tributaries to the Amazonas Basin in the east. This makes it possible for large lahars to travel very long distances in either direction. Usually, lahars are created by rain- or lake water and loose ash; when the mixture reaches a certain condition, large amounts of this fresh-concrete like mass starts moving with high velocity down any available path. However, the water on Cotopaxi often comes from a different source:
once a pyroclastic flow happenes, it melts part of the glacier, and the melt water causes a lahar right on the spot together with the just erupted ash. So, on glaciers it is always a double risk, PF and lahar, and no rainfall would forecast this danger. – Having said this, of course, heavy rains would also do the same as elsewhere on volcanoes: mobilize the dry ash deposits and send them as lahars down the valleys… so that’s the third brother of the siblings of doom. Really, no scaremongering here. Keep alert of the danger of lahars – not only near Cotopaxi!
If there were to be a very large eruption, enormous lahars (mudflows and debris) would transit through drainages in densely populated areas like the Inter-Andean Valley between Mulaló and Latacunga, and part of the valley of the Chillos. It has been estimated that more than 300,000 people live in areas directly threatened by lahars in eruptions similar to those that repeatedly occurred in the 18th and 19th centuries. In addition, the fall of ash produced during an eruption of Cotopaxi could affect a significant portion of the Sierra and the Costa del Ecuador, including the capital Quito. Ironically (or irresponsibly?), the international airport of the Cotopaxi region is situated at the foot of the volcano, directly where one of the morphological features of the mountain would suggest potential lahars to come down. 😦
Cotopaxi is one of Ecuador’s most impressive volcanoes, therefore there exist a significant number of historical chronicles that start at the time of the Spanish conquest. For those of you interested in historical descriptions, these are some of the collectors/publishers: Hantke and Parodi (1966), Hradecka et al. (1974), Hall (1977), Simkin et al. (1981), Barberi et al. (1995).
According to the GVP, Cotopaxi has had approximately 30 eruptions reported in the 19th cty. and 11 in the 20th cty. (Strangely, on Feb. 17-19, 1942 a fairly big eruption with a VEI 3 is marked “[uncertain]”- how could it go unconfirmed for 75 years? Has nobody seen it, felt the ash, no official reported on it? In more recent years, many studies of the lava and tephra layers have been conducted, how could that most recent eruption not be confirmed by scientists?)
These eruptions were typically accompanied by regional scoria and pumice ash falls, blocky lava flows, scoria pyroclastic flows, and lahars, all of andesitic character (SiO2=56–58%). However, during the past 10 000 years, rhyolitic eruptions have periodically taken place in its predominantly andesitic development, at intervals of approx. 2000 years.
The Chillos Valley Lahar (CVL) through Ecuador’s Inter-Andean Valley was probably one of the most catastrophic geologic events to have taken place during the Holocene. It occured ~4500 years BP and was caused by a rhyolitic ash flow that followed a small sector collapse on the north and northeast sides of Cotopaxi. It descended Cotopaxi’s northern rivers, with high flow gradients (4–5%) for the first 25–40 km and lower gradients (1–2%) thereafter. Two arms of the flow united in the Chillos Valley – where it spread to form an impressive width of 11 km with deposits of up to 150 m thickness – then descended the Andes’ flanks. So it had two steep descents to reach sea level, that of the cone itself (~3500 m drop) and that of the Andes’ western flank (~2500 m drop). It travelled all the way down to the Rio Esmeraldas floodplain until it reached the Pacific Ocean. Thus, this debris flow traveled a total of 326 km and left a deposit, averaging 2 m thick, over 440 km2. Its submarine extension onto the offshore platform is unknown. (Mothes/Hall/Janda 1997)
The first European who attempted to climb Cotopaxi (and many other Andean volcanoes) was the great German geographer and explorer Alexander von Humboldt in 1802, but he had to abort the ascent at 4500m elevation. It seems he was not a great painter but took care of the details and inspired others. He also wrote detailed descriptions of his journeys and findings, and I am eagerly awaiting the completion of the digital version of his books. – Cotopaxi was then climbed completely for the first time in 1872 by the German Wilhelm Reiss and Colombian Angel M. Escobar, who started from the southwest flank. The following year four Ecuadorian and another German mountaineer conquered the volcano.
The Kichwa people of Tigua, the indigenous tribe of the area, are world-renowned for their traditional paintings on sheepskin canvases. Historically, the Tigua people have been known for painting highly decorative masks and drums; painting on flat surfaces is somewhat of a modern occurrence. Today, Tigua paintings can be found for sale all over Ecuador, particularly in touristic areas. The volcano Cotopaxi is depicted in the landscape of most paintings, as it holds particular cultural significance in the region.
The art is pure; the artists are outside the mainstream and have no training. The work is strangely appealing and not always pretty – but it is fresh, colorful, honest, and personal. Tigua artists are celebrated for their use of vibrant colors and simplistic themes. Most paintings depict scenes of pastoral life, religious ceremonies, and festivals. Most of the people here farm the mountain slopes and valleys, herd sheep and llamas and grow their crops on the patchwork of steep, windswept fields. Tigua artists are deeply bound to the land. Even the most successful painters still plant and harvest their own fields of potatoes, beans, and grains.
UPDATES on Cotopaxi activity
18 Aug. 2015
Report Monday, 17 Aug. 2015: Seismicity has increased in the last 24 hours from 120 to 300 events of long period (LP), 2 to 1 hybrid (HB), 1 event volcano tectonic (VT) and from 9 to 142 tremor episodes.
It is a clear day at the volcano, and I was lucky enough to gain access to the IGPEN website for a few minutes, it must be overrun by people wanting to watch. Activity is on the far side of the volcano, it does look like pyroclastic flows going down.
Timelapse from 18 Aug. 2015, 12:11 – 13:06. Click image to start animation in a new tab:
19 Aug. 2015
Now we know why it is almost impossible to get any meaningful actual information on Cotopaxi: “At a meeting between representatives of journalists from Cotopaxi and the National Communications Secretariat (Secom), two local media were informed about investigative proceedings initiated against them for alleged violation of the “state of emergency”, which imposes censorship prior to information on the Cotopaxi volcano eruption process.” – So, the press is not permitted to publish anything about the eruption apart from what the official reports give to the public… great! Not enough that the official daily reports themselves are a day late, they also tell you next to nothing in a few lines. If journalists want to write anything more, they have to send in the material for censoring first – how many days will that take? And where are the actual news… in the heads of the authorities? What good is that to the population, or to us? We want to know how the eruption is going… I am reminded of El Hierro… http://www.cotopaxinoticias.com/seccion.aspx?sid=29&nid=20946
23 Aug. 2015
Today the Bulletin states: “the Geophysical Institute of the National Polytechnic reports that the Cotopaxi volcano has the same activity as on previous days. …“ Yet, to my untrained hobbyist’s eye it looks as if the activity has been rising steadily, particularly obvious in the last few days… See the seismograms from the start (click to enlarge):
Actually, you don’t need a magnifying glass or a couple of years’ training to see an increase in activity here. (If I were wrong, so would be the thousands of other John Does who download the reports and read the seismograms every day, in order to find some information that might have been held back by the authorities). Rant over. 🙂
So, the activity of Cotopaxi has increased somewhat but is still moderate; copious amounts of ash are blown constantly to the W and SW today. Villages perform evacuation drills daily, and are trained in how to protect their lives and their lifestock.
The output of SO2 has decreased considerably from over 12K t/d on the 20th to less than 2K t/d today. – The episodes of volcanic Tremor have (in previous reports) been published by number without giving durations, which is actually useless for John Doe. The first half of today there were 8 and the second half 1 (one!) – compared to 140 yesterday. Luckily, someone had the bravery to explain that it was one episode of continuous tremor since abt. 6 in the morning (
he could have left it to John Doe to conclude that tremor had almost ended 😛 )!
A new webcam has been installed which seemingly is not getting switched off in late afternoon. Its location seems to fall under the censorship laws, and I have not seen it by daylight yet – it could well be in Quito: http://www.seguridad.gob.ec/volcancotopaxi/index.php/en-vivo-volcancotopaxi/
Also, MalinPebbles has now a dedicated page for Cotopaxi with 6 webcams, important-links collection and more: http://volcams.malinpebbles.com/pubweb/Cotopaxi.htm
29 Aug. 2015
From Cotopaxi Special Report No. 12
Seismic energy has reached and maintained a high level in the last three days. In the August 26 flyby high temperatures were observed in the emission column. Also higher temperatures were found on the flanks, where reduced snow cover allowed measurements. The output of ash and gases (high SO2 content) is continuous.
Thermal image of S and SW flank of the volcano where temperatures observed (TMA) are indicated. Right: corresponding visual image with annotations (Photo: P. Ramón IG/PN). Click to enlarge.
Enjoy! – GRANYA
SOURCES & FURTHER READING
– Risk Areas -> SAFE PLACES – (updated, pdf)
– Cotopaxi Volcano Special Report No. 7-2015 (15 Aug 2015)
– IGEPN, Cotopaxi
– Local news on “Cotopaxi Noticias” (“CN”)
– Reporte de actividades del volcán Cotopaxi – Boletín de prensa – COE, Bol No. 1 (14 Aug 2015)
– State of affairs explained by authorities (“CN”, 15 Aug. 2015)
– Volcanic hazards associated with Cotopaxi (IGEPN)
– The enormous Chillos Valley Lahar:… from Cotopaxi… (1997)
– Wikipedia, Culture of Ecuador
– L’Art pictural Tigua en Equateur
– EcuRed – Volcán Cotopaxi
– Hazard Maps (North and South), Mapa de Peligros – Cotopaxi
– Frederic Edwin Church. Wikipedia