Predicted ash hazards from potential eruptions at Nevado Sabancaya, Peru: HYSPLIT and remote sensing
Rankin, Andrew J.
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Nevado Sabancaya (15°47'S, 71°51'W) produced a series of vulcanian eruptions from May 1990 through 1998. Ash from these eruptions falling onto the ice fields of Nevado Hualca Hualca (just north of Sabancaya volcano) melted the ice and produced small lahars that flowed toward the town of Maca near the Rio Colca Valley. In an effort to understand potential hazards from an eruption of Nevado Sabancaya, this study mapped volcanic features for the three volcanoes of the Ampato Complex (Nevado Hualca Hualca to the north, Nevado Sabancaya, and Nevado Ampato to the south), including: snow and ice fields, drainage channels, and volcanic products. The greatest area of ice and snow is located atop Nevado Hualca Hualca, and Hualca Hualca has the only drainages that flow to the north into the Rio Colca Valley. Melt water from atop Nevado Sabancaya and Nevado Ampato would flow south into the Rio Sihuas Valley. While monitoring occurred throughout Sabancaya's most recent eruptive phase (1990–98), little was done to study the impacts of larger, future eruptions. In this study, the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to simulate eruptions from 2005–2011 to find areas around the volcano where ashfall could create hazards in future eruptions; plume heights of 4 km, 12 km, and 20 km were used. Results show that there are two different pathways in which ash will disperse from the volcano, depending on the season. In the summer, ash remains to the south, but close to the volcano, but would still likely impact air traffic in Arequipa, Peru. The winter season is dominated by a strong westerly wind that disperses the plumes into central Bolivia, and could affect air traffic in and out of La Paz. An increase of initial plume heights increases the area of dispersal up to a 12-km-tall plume. Plumes higher than 12-km do not disperse outwards much more but do have slight changes. The effects from future eruptions will thus be determined by not only the size of the eruption, but the time of year in which it occurs.