PREDICTED ASH HAZARDS FROM POTENTIAL ERUPTIONS AT NEVADO SABANCAYA, PERU: HYSPLIT AND REMOTE SENSING

Nevado Sabancaya (15° 47’S, 71° 51’W) is an andesitic stratovolcano in southern Peru that produced a series of vulcanian eruptions that began in May, 1990 and continued intermittently into 1998. Typical eruptions generated ash columns that extended ≥4 km above the summit of the volcano; ash was commonly transported as far as 10 km from the summit. Over 35,000 people live on or close to Nevado Sabancaya, and its nearness to Peru’s main airport in Arequipa requires that we understand the potential hazards from its future eruptions. The HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) model simulates a volcanic eruption column with user-specified heights; ash dispersal is modeled using stored meteorological data from December 2004 until the present. We used HYSPLIT to examine ash dispersal from hypothetical Nevado Sabancaya eruption columns with heights of 4 km, 12 km, and 20 km above the summit and we applied meteorological data from January 2005 through December 2011. Preliminary results from the 4-km-tall simulated eruption columns suggests that the autumn and winter winds around the volcano push the plume to the southeast out of Peru and into Bolivia; and occasionally ash moves into Paraguay from mid-April through late-October. From late-October through mid-April, spring and summer winds are weaker, with ash generally remaining in southern Peru near the volcano or dispersing to the southwest into the Pacific Ocean. We will integrate results from the HYSPLIT models (using a range of eruption column heights and seasons) with Landsat and ASTER imaging of areas around the volcano, using ArcGIS 10. These merged data sets will be used to determine the areas in central South America with the highest probability of ash fall from Nevado Sabancaya. In addition, we will attempt to identify and map Nevado Sabancaya ash fall deposits, using these combined data sets. This study will help on the understanding of what areas may be more at risk from future activity by Nevado Sabancaya should the volcano erupt with previous or increased intensity.