Earth news: Los Nevados del Huila Erupts In Columbia

Los_nevados_columbia
Elaine Meinel Supkis

A volcano in Columbia caused a landslide/eruption/flood. This valley has been the site of previous disasters as it is one long chain of volcanos and mountains, the northern sector of the Andes. One feature of volcanos is how 'sleeping' volcanoes can suddenly not only erupt but completely explode with very little warning.

From Associated Press:

Thousands of people were evacuated after a long-dormant volcano erupted late Tuesday and again early Wednesday, provoking avalanches and floods that swept away houses and bridges.

The Nevado del Huila volcano's eruptions were its first on record since Colombia was colonized by the Spanish 500 years ago.

There are about 10,000 people living in the area around the volcano, and about 3,500 had been evacuated, Luz Amanda Pulido, director of the national disaster office, told The Associated Press after flying over the volcano in southwest Colombia.

These volcanos are 'dormant' until they are not 'dormant'. Namely, this classification is spurious. Some calderas and volcanos might be inactive such as some of the ones around Tucson, Arizona, for example. But generally, it is a guessing game, not a science. It seems volcanic rifts are possibly one time events, the ones that leave behind various forms of 'sawtooth' mountains.

This particular volcano is actually rather active on the geological scale. About 20 years ago, we saw a major volcanic eruption in Mexico which clearly shows there is no such thing as a truly 'dormant' volcano: From Vulkaner:

El Chichon is the most southern and eastern volcano in Mexico.

It is a small, but powerful andesitic tuff cone and lava dome complex that occupies an isolated part of the Chiapas region far from other Holocene volcanoes. Prior to 1982, this relatively unknown volcano was heavily forested and of no greater height than adjacent non-volcanic peaks. The largest dome, the former summit of the volcano, was constructed within a 1.6 x 2 kilometer summit crater, created about 200,000 years ago.

Two other large craters are located on the SW and SE flanks. More than a half dozen large explosive eruptions have occurred since the mid-Holocene. The powerful 1982 explosive eruptions of high-sulfur, anhydrite-bearing magma were accompanied by devastating pyroclastic flows and surges and destroyed the summit lava dome. The eruptions created a new 1-kilometer-wide crater that now contains an acidic crater lake.

El Chichon might have erupted from about 270 CE and every 500 to 600 year since, in about 700, 1350 and 1850, with explosive eruptions followed by pyroclastic flows. Then suddenly in 1982 it woke up again, way out of schedule. Prior to 1982, it was thought to be extinct. Consequently, activity of the volcano was not being monitored and the 1982 eruption was a total surprise (although, with hindsight, local inhabitants had noticed increased earthquake activity for some months prior to the first eruption).

This eruption buried a city as well as much of the farmlands surrounding it. The ash was so thick, it was night for 44 hours in a nearby city. The volcanic tuff was so thick, it was more than 30' in places. The entire top half of the volcano blew up and turned a dome covered with forest into a steaming hot caldera.

There were a few small forewarnings it was going to blow up. The streams and rivers running down from this volcano smelled of sulfur and became much hotter. Micro quakes rattled the people living on the flanks of the volcano but since it was 'dead', no one took all that seriously. It erupted the first time with no warning. This was the small, 'normal' eruption with a big plume and so on. But before anyone could really be evacuated, as the volcanists flown into the region could barely set up their equipment, the top half of the mountain exploded and anyone within 30 miles of it was buried under many feet of tuff and rocks.

Why do they suddenly blow up like this? The Andes has armies of such mountains. Mexico has quite a few and there are several important ones in the North American west as well as Alaska, of course. We know that Yellowstone is this hot spot that creates one giant caldera after another, each time, very explosively. The nastiest volcanic events in all of North America come from this one entity. But El Chichon was a fairly quiet mountain and no one had seen it erupt or even hiss a tad since the European invasion of Mexico. There are similar potential volcanos all over the place. We can't tell if they are active until they decide to be active.

Here is a photo from the National Geographic that came out back when no big volcanos had erupted in quite a while.

From my parent's book, 'Sunsets, Twilights, and Evening Skies':

There had been so little volcanic action since 1900, volcanists were quite annoyed. Off in Indonesia, Agung suddenly had a very powerful eruption. Suharto was badly shaken, politically, since it was considered his fault the Volcano Gods didn't like him. Communications and observation of the earth were so scant back then, we knew about this eruption long before it made the news because it lit up the sky so amazingly.

I learned years ago to put my hand over the sun to see if there is any 'haze' that is different from normal cloud cover. One can even see the fine, red dust from Mongolia after a bad drought and windstorm this way, the sky has this even copper sheen. With white dust from volcanos, this is different from high cirrus clouds because it is even from horizon to horizon. Since 1963, a host of volcanos have put into the stratosphere all sorts of combinations of dust and or aerosols and each combination creates different light effects at sunrise and sunset as well as affecting the weather tremendously.

Indeed, I would suggest the earth is undergoing a major spasm right now. The frequency of major earthquakes coupled with volcanic actions suggests the earth goes through phases and this is an active phase. Certainly, the sudden releasing of pressure on several continents due to swift ice melting might be affecting the entire planet.

From the USGS:

By removing a large part of a volcano's cone, a landslide may abruptly decrease pressure on the shallow magmatic and hydrothermal systems, which can generate explosions ranging from a small steam explosion to large steam- and magma-driven directed blasts. A large landslide often buries valleys with tens to hundreds of meters of rock debris, forming a chaotic landscape marked by dozens of small hills and closed depressions. If the deposit is thick enough, it may dam tributary streams to form lakes in the subsequent days to months; the lakes may eventually drain catastrophically and generate lahars and floods downstream.

The valleys around today's volcanic event have seen many landslides in the past. It is a very dangerous region for humans. Landslides are like tsunamis in many ways. Instead of happening in the ocean and sweeping towards land, it is land sweeping into lakes and rivers and causing them to surge as well as simply covering everything in tons of dirt and rock.

Today's event is similar to the one back on June 6, 1994: From USGS:

Within minutes of a magnitude 6.4 earthquake beneath the SSW flank of Nevado del Huila volcano, dozens of landslides swept from the steep valleys above Río Paez into the river. The landslides quickly turned into debris flows, which joined to produce a single enormous flow of water, rocks, soil, and trees in Río Paez. The lahar destroyed most or parts of several towns along the river, including Dublin, Irlanda, Toez, and Belalcazar, killed several hundred people, and displaced about 20,000 people from their homes. Six bridges and >100 km of roads were destroyed.

Map from the USGS.

The huge flow wave originated from both hydrothermally altered rocks of Huila Volcano and the ash-mantled terrain surrounding the volcano. Whether triggered by a large earthquake, intense rainfall (for example, see Casita Volcano), or both, this tragic event illustrates that both volcanic cones and steep hillslopes around them can collapse to form landslides and debris flows.

This region is full of wild life. They survived so long because the region is dangerous for humans. Even as humans invade increasingly dangerous zones, the wild animals retreat into the mountains. One of these is the endangered species called 'the Mountain Tapir'. From Tapirs.com:

Mountain tapirs occupy the mountainous terrain of Colombia, Ecuador and Peru. They weigh up to 225 kg and can be up to 1.8 meters long. They are an endangered species, and the rarest of the tapir species.
*snip*
A unique feature that tapir posess is its fleshy prehensile nose that it uses to grab leaves and even use as a snorkle while swimming. Their hides are very tough but streamlined for easy maneuvering in the forest. Tapirs are "seed dispersers." They eat seeds that are then dispersed in their scat which helps the forest to regenerate.

Tapirs are herbivores best suited to primary or old growth secondary forest, and their reproduction is slower than most mammal species due to a long gestation period (13 months) and to the fact that there is only one offspring per gestation.

As these curious little animals with many hooves on their feet, distant relatives of the rhino. They are now scattered along patches of volcanic lands mostly in Columbia. Just like the Chiapas and the Agung events, poltical fortunes and rebellions accompany volcanic eruptions. And these rare animals struggle to live in this difficult situation.

This is true of all caldera or volcanic regions. For example, the USA has confined most of the remaining members of several endangered species that once roamed North America, in Yellowstone. It is a National Park and very pretty. It also can blow up totally with virtually no warning, certainly not enough time for humans to capture or herd out all the endangered species we parked there!

Of course, if it blows up really big, we might be the endangered species. This is why volcanists along with astronomers are so vital: they study the real dangers we face aside from our own stupidity.

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