Sirens Warn Chilean Town of Impending Volcanic Eruption

Siren blasts created great concern in the southern Chilean town of Pucón on the afternoon of Easter Sunday. The residents feared that a second eruption of Mount Villarrica, a large glacier-covered volcano close to the town, would occur at any moment. The dramatic lava flows and enormous ash clouds from the first eruption on March 3 were fresh in their minds. And other events Sunday morning—noisy explosions, a large new ash-cloud—had put residents on edge.

The VIllarrica Volcano, with its ice cap. Pucon at the left edge of the lake.
The Villarrica Volcano in upper left, with its ice cap. Pucon at the left edge of the lake. (Source: Google Earth)

This volcano, 2840 meters in height, has erupted a number of times over the centuries, and is well-known as one of the most active volcanoes in Chile. The glaciers that form the ice cap on its summit create significant risks. This ice cap, about 40 square kilometers in area, could release large volumes of water if lava reached it directly, sending large flows of ash, mud and debris rushing down the mountain to nearby agricultural areas and towns.

Two hours after the alarm, the municipality of Pucón issued a statement that “the sirens that were activated in Pucón were only providing a preventive measure, and were not intended to evacuate the town, but only to alert residents, because of the greater activity of the volcano.” The officials went on to say that one national agency has retained its warning level at yellow, and another at orange, as they both have for some days, so that circumstances had not changed in any serious way. The sirens, they said, were simply a reminder to stay alert in case there was a shift in the risk.

The first agency is the ONEMI, the National Emergency Office, a branch of the Ministry of the Interior and Public Security. Their official statement stated that there was little risk of a serious eruption of lava. They offered the comment that the globs of lava that were shooting from the crater were traveling at most 200 meters, a distance which they deemed safe. They based their assessment on recent visual observations of the volcano and on the reports of the second agency, OVDAS, the Volcanic Observatory of the Southern Andes, a branch of the National Service of Geology and Mining (itself a branch of the Ministry of Mining). This agency maintains  8 seismographs on the volcano, as well as 4 GPS stations, 2 instruments to measure sulfur dioxide concentrations, 4 webcams, a microphone to record sounds and other instruments to measure surface movements.  (You can see the webcams here.)

In a statement today, Carlos Cardona, the OVDAS representative, emphasized that there was little change in the level of seismic activity, the most important precursor of eruptions, though he also stressed that the volcano was unstable, the situation could change, and that he and his associates were closely tracking the data that came in from their instruments. These comments might not have provided much assurance to the town officials and residents, who heard the loud booms of explosions and saw the ash clouds.

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Pucón Municipality Facebook Page

A number of the town’s residents resented what they felt was a false alarm on the part of the official who sounded the alarms from the fire station. They provided ample testimony of their views on the municipality’s Facebook page. Several described how restaurants and supermarkets closed, how the staff at the local prison did not know what to do, and how the parents of children who board in Pucón during the week and return home to outlying villages on weekends were also uncertain whether to send their children back to school. Several people mentioned the story of the boy who cried wolf (in Chile, this boy is named Pedro). Andrea Handal Tarud wrote, “But your official procedures state that the sirens sound to tell people to EVACUATE, how can we know if it’s a preventive alert or real? Be serious, don’t break your own procedures, with that you only confuse people and alarm them unnecessarily.”

“What a way to confuse people!” Heide Hillis wrote. “The few tourists who were around rushed from Pucón, and the local people were panic-stricken. HORRIBLE management of the situation.”

Perhaps the two agencies, ONEMI and OVDAS, will follow the suggestion of another resident, Flor Vega Lagos, who directed them, in her Facebook comment, to come to an agreement on the level of the alert. It seems more likely that local residents and national agencies alike will continue to scrutinize the multiple and changing signs of the volcano, each forming their own judgment.

To learn more about the eruption of Villarrica in March, look here.

Eruption in Glacier-covered Volcano in Chile

One of South America’s most active volcanoes, Villarrica, erupted Tuesday, 3 March 2015,  around 3 a.m. local time in Chile, creating a danger that lava would interact with the large ice cap on the mountain. The volcano spewed a lava fountain 1.5 kilometers into the air, and the pillar of smoke and ash reached 6-8 kilometers in height. Fortunately, the National Emergency Office issued a red alert and ensured the evacuation of roughly 3300 people from the volcano’s vicinity, especially residents from the town of Pucón. This area experienced  many moderate to large eruptions, including events in  1640 and 1948 which appear in the historical record, and earlier ones attested to by indigenous populations of the area and by geological evidence.

The upper reaches of the volcano are covered by an ice cap about 40 square kilometers in area, including the Pichillancahue-Turbio Glacier. This 2840 meter-high mountain is a popular destination for hikers, who are fond of peering inside of the volcano. What differentiates Villarrica from many  other volcanoes is that it contains an intermittent lava lake within its crater. In fact, Villarrica volcano is composed of layers of hardened lava and volcanic ash from previous eruptions. It is capable of erupting explosively  due to high pressure that results from the release of dissolved gas as magma rises to the surface. These explosions are often accompanied by loud sounds that can be heard over great distances.

The eruption can be seen in this dramatic time-lapse video, which starts in black and white, and then shifts to color.

There are three major interrelated concerns about this eruption.  Firstly, the lava could melt the glacier ice and snow on the sides of the volcano, causing massive lahars (mud and debris flows), much like the ones that occurred during the eruptions of 1964 and 1971. Secondly, the noxious volcanic ashes could pervade in the air. During the 1971 eruption of Villarrica, at least 15 fatalities from the inhalation of toxic gasses were reported. Finally, there is a somewhat lower risk of a large releases of volcanic ash, which could affect human health, damage power transmission lines, and harm vegetation.  Previous eruptions of Villarrica have released smaller amounts of ash; paradoxically, these have protected the glaciers by insulating them and protecting them from incoming solar radiation.

Eruption of Villarrica, 3 March 2015 (source: Kalvicio de las Nieves)
Eruption of Villarrica, 3 March 2015 (source: Kalvicio de las Nieves)

At the time of posting, the volcanic activity is diminished, with much reduced lava emissions and lesser seismic activity. Alerts remain at the orange level for the present.

For other stories on volcanic eruptions near glaciers, look here and here