Multiscale and multitemporal surface temperature monitoring by satellite thermal infrared imagery at Mayon Volcano, Philippines

Mayon Volcano on eastern Luzon Island is the most active volcano in the Philippines. The high level of vulnerability to volcanic hazards is apparent since Mayon is surrounded by eight cities and municipalities with a total population of approximately one million inhabitants. Thus there is an urgent need to develop and expand reliable and affordable long-term methods in volcano monitoring. Despite abundant open access satellite dataset archives, satellite remote sensing has been underutilized in Mayon's hazard mapping and monitoring system. Here, we perform monitoring analysis on a nineteen-year time series of Land Surface Temperature (LST) obtained from satellite thermal infrared images. Both ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) thermal imagery (with 90 m spatial resolution) and MODIS (Moderate Resolution Imaging Spectroradiometer) LST products (1 km spatial resolution) are used for the analysis. The Ensemble Empirical Mode Decomposition (EEMD) is applied as the decomposition tool to extract components of different timescales from the LST time series. Physical interpretation of decomposed LST components at various periods are explored and compared with Mayon's eruption records. Specifically, the LST annual period component is compared to regular annual cycle air temperature. Results show that LST annual period component tends to lose its regularity following an eruption. The dissimilarity of the two time series has been taken as an indicator of volcanic restlessness. Trends of different timescales based on LST components have been constructed, which all indicate the rising trend. This means that Mayon volcano will remain restless in the future decades. This study presents the advantages and effectiveness of satellite remote sensing on volcanic monitoring.