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Volcanowatch

October 29, 2009

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.


Lessons Learned from the Armero, Colombia Tragedy

Late in the evening on November 13, 1985, most of those living in the Colombian town of Armero, on the shores of the river Lagunillas, were in bed. The nearby volcano, Nevado del Ruiz, had been quiet for the past couple of months, and the mayor and the town priest had assured the people of Armero that they were safe for the night.

Unfortunately, a storm had been brewing over the area, and the explosive eruption that occurred on the mountain, obscured by rain that night, went unnoticed by Armero residents. Those who experienced the eruption had no way of relaying information quickly and efficiently to Armero, the place most in danger.

Nevado del Ruiz is a stratovolcano, akin to Washington's Mount St. Helens, topped by glaciers, rising 5,389 m (17,784 ft) above sea level. Such volcanoes are especially dangerous, because heat from the eruptions melts the ice to create lahars, or mudflows of volcanic debris. These are not slow, cumbersome mudflows, but fast, deep, and destructive walls of debris and water.

The volcano first began to stir about a year earlier, its reawakening marked by a swarm of earthquakes. Fumarolic activity in the summit crater began around the same time. A visiting UN geologist advised the installation of monitoring equipment and the creation of a hazard map and evacuation plans. But Colombian scientists lacked the expertise, government support, and equipment necessary to effectively monitor the volcano and relay information to public authorities. They requested aid-both equipment and scientists-from foreign countries and were sent a few seismographs without proper instructions on how to operate the instruments and analyze the data.

In addition, the Colombian government was preoccupied with civil matters. In Bogot?, Colombia's capital, guerrilla warfare had broken out, and the Colombian President sent troops to quell the rebellion. To the government, the unstable political situation was more pressing than the volcanic activity. It did not help that the information about threats from Nevada del Ruiz provided to officials by various visiting and Colombian scientists was often contradictory and vague.

A minor explosive eruption on September 11 and a calmer political situation refocused officials on volcanic matters. City, county, and federal officials started meeting with scientists to discuss hazard map creation, evacuation plans, and possible eruption times and outcomes. Progress finally started at the federal and county levels, but the little town of Armero, built on old lahar deposits 45 km (28 mi) from the volcano, still went mostly unnoticed by government officials.

Before an effective line of communication and evacuation plan could be created, Nevado del Ruiz erupted again and sent lahars racing north and east through the deep river valleys on Nevado del Ruiz's flanks. With little warning, the river Lagunillas heaved its muddy contents onto the flatlands, directly into the city of Armero.

Within minutes, 23,000 people-most of the town's inhabitants-were killed, entombed within a concrete-like mixture of mud, vegetation, buildings, and everything else swept away by the lahars. Sadly, the lahars reached Armero approximately two hours after the eruption-plenty of time for the people to have evacuated to higher ground, had they been notified more quickly.

The 1985 eruption of Colombia's Nevado del Ruiz is the second most deadly volcanic eruption of the 20th century, resulting in the deaths of more than 25,000 people. Communities worldwide learned valuable lessons from this calamity. These include proper equipment and training for monitoring scientists to understand and help others understand what is happening.

Effective communication between all parties is one of the most essential components of living around an active volcano. When Mount Pinatubo in the Philippines awoke in 1991, the entire volcanological community responded, thus averting a disaster like the Armero tragedy. Every day, we continue to learn more about the volcanoes of our Earth. Looking back into the past is another way to catch a glimpse of the future.

Kīlauea Activity Update

Lava continues to erupt from the TEB vent on Kīlauea's east rift zone and flow through tubes to the ocean at Waikupanaha. Surface flows were sporadically active at the end of the Kalapana access road adjacent to the Hawai`i County lava viewing area trail at least through Thursday (the date of this writing). Other active surface flows were scattered over a broad area extending up to several hundred meters (yards) to the west of the end of the road. Relatively bright glow has been visible at night in the Pu`u `Ō `ō crater from a new or enlarged vent on the crater floor.

Glow above the vent at Kīlauea's summit has been visible at night, but the lava surface has receded below the view from the webcam on the rim of Halema`uma`u above the vent and is not currently visible. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.

summit has been visible at night, but the lava surface has receded below the view from the webcam on the rim of Halema`uma`u above the vent and is not currently visible. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.

Visit our Web site (http://hvo.wr.usgs.gov) for detailed Kīlauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kīlauea activity summary; email questions to askHVO@usgs.gov.

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Updated: November 29, 2009 (pnf)