INGEOMINAS and VDAP Responses at Nevado del Huila, Colombia
Since VDAP was created in 1986 following the Nevado del Ruiz tragedy, the team has worked closely with the Instituto Colombiano de Geología y Minería (INGEOMINAS) on various crisis-response and capacity-building projects, including direct involvement in establishing the three volcano observatories now functioning in Colombia.
Like Nevado del Ruiz, Nevado del Huila is a large snow-and-ice-clad volcano capable of generating large, exceedingly dangerous, debris flows (lahars) when it erupts. In 1994 the Huila region was the site of a M 6.4 tectonic earthquake that induced lahars and killed about 1000 people. These fatalities combined with the 1985 Armero disaster at Nevado del Ruiz, greatly enhanced the awareness of lahar hazards in the country. For more information about the 1994 earthquake and images, please see the VHP article Landslides and lahar at Nevado del Huila Volcano, Colombia.
Successful Eruption Forecast and Evacuation at Huila, Colombia 2007 - 2008
At the request of INGEOMINAS, VDAP responded to an increase in activity at Huila following the February 1819, 2007 phreatic eruption and lahar. VDAP and INGEOMINAS worked together to develop a protocol for warnings and forecasts. A key part of that protocol was the recommendation: "If seismicity climbs for an hour or more (RSAM values or earthquake counts) with frequent M1M2 events, initiate a calldown." Subsequently, during the short buildup to the April 19 phreatic eruption and lahar, INGEOMINAS staff used this procedure and a color-coded warning scheme to alert public officials, who evacuated thousands in the Rio Páez shortly before a lahar swept the drainage. No fatalities resulted from the eruption or lahar.
One of the World's Largest Lahars
On November 14, 2008 a VDAP scientist collaborating with INGEOMINAS in the U.S. noticed an interval of repetitive "drumbeat" earthquakes on seismic data shared via the Internet. On November 19, VDAP and INGEOMINAS forecast an eruption for November 20 based on the earthquake activity.
The eruption began at 21:45 on November 20 and INGEOMINAS called for evacuations. An ash column rose to 50,000 feet. By 22:05, Belalcázar (population 5,000) was completely evacuated. At 22:20 a giant lahar, one of the largest monitored in the world with an estimated volume of 300,000,000m3, inundated parts of the town of Belalcázar. On November 21, a lava dome was spotted. Because the volcano was monitored, a communication system was in place, and evacuations were successful during the night, there were no fatalities in Belalcázar.
Based on this collaborative effort of INGEOMINAS and VDAP, an effective nighttime evacuation avoided a repeat of the tragedy of November 13, 1985, when lahars from Nevado del Ruiz volcano swept through Armero, Colombia in the middle of the night and killed more than 23,000 people. The extremely effective response by INGEOMINAS is a fitting memorial to those lost at Armero.