Are Palmira sand dunes related to Sangay volcano eruptions? New insights derived from sand dunes mapping using sentinel 2 data

Abstract

Palmira desert, located in the central Andes of Ecuador, constitutes one of the few deserts that present dark sand dunes, mostly of volcanic ashes. The distribution of these sand dunes was mapped through Maximum Likelihood Classification based on spectral bands and indexes derived from Sentinel 2 data. The distribution of these sands showed an E-W pattern between Sangay volcano and Palmira desert, supporting the Palmira sand dunes' provenance from this volcano. This pattern is also evident in the ash plume frequency map derived from Volcanic Ash Advisory Center data where most ash plumes point to west, to the Palmira desert location. Regional wind models indicate this pattern is due to the dominant E-W winds in the region, which transport ashes from Sangay volcano to Palmira desert, and opposing winds from the west prevent these ashes to be transported beyond Palmira desert location. This provenance from Sangay volcano is also supported by the spectral signature similarity between Palmira sand dunes and Sangay volcanic deposits, suggesting ashes of intermediate composition with abundant ferrous minerals.