Application of airborne hyperspectral remote sensing for mapping surface mineral and volcanic products at 2014-2015 Holuhraun lava flow (Iceland) using Sequential Maximum Angle Convex Cone (SMACC) method

Introduction & Objectives Holuhraun lava flow was the largest effusive eruption in Iceland for 230 years, with an estimated lava bulk volume of ~1.44 km3 and covering an area of ~84 km2. The six months (August 2014-February 2015) long eruption at Holuhraun 2014-2015 generated diverse surface environment. Therefore, the abundant information of airborne hyperspectral imagery above the lava field, calls for the use of time-efficient and accurate methods to unravel them. (2) Datasets and Method The hyperspectral data acquisition was acquired five months after the eruption finished (4 September 2015), using an airborne FENIX-Hyperspectral sensor that was operated by Natural Environment Research Council Airborne Research Facility (NERC-ARF). Sequential Maximum Angle Convex Cone (SMACC) was applied to extract end-spectra and end-images of a FENIX scene of Holuhraun. In this study, we subset the data to focus on the area around eruption vent which considered have more diverse surface. The dataset contains 622 channels from 0.3 μm to 2.5 μm with 4 meter pixel resolution. The data were atmospherically corrected by Quick Atmospheric Correction (QUAC). (3) Results (4) Discussions and Conclusions Fifteen endmember spectra (End-spectra) were sought together with their abundances. Selected are indicated by the numerals on the image in Figure 1. The abundances were constrained to be positive but no restriction was placed on their sum. The first endmember (Endmember 1) was chosen as the brightest spectrum which represented saturated incandescent lava.-End-spectra 1, 4, 5 and 13 are located in bright regions in false colour (SWIR-NIR), which represent the incandescent lava. Their spectra and the abundance are illustrated in Figure 3.-End-spectra 3, 6, 8 and 12 represent an oxidized surface. The oxidized surface endmembers have the highest abundance fraction around the vent which is good agreement with the field observations (Figure 8). The spectra and abundance maps are illustrated in Figures 4.-End-spectra 2, 7, 11 and 15 represent sulfate mineral. The sulfate mineral endmember has the highest abundance fraction around the lava pool with a white surface colour and are also found in small fraction around the vent. The spectra and abundance maps are illustrated in Figures 5. Most pixels are described by a small subset of the end-spectra.-End-spectra 14 represents water. This endmember has the highest abundance fraction around the river and a small fraction around the lava pool.-We consider End-spectra 9 as noise that occur in the spectra due to corrupted bands. In total, we acquire fifteen spectral endmembers (six surface type) and abundances (oxidized surface, sulfate mineral, water, incandescent lava and noise) that represent pure surface materials in a hyperspectral image. The SMACC methods offers fast selection of endmember for the volcanic products segregation. However, the ground truth spectra are needed for further analysis.