Analyze the spatial distribution of lava flows in Al-Ays Volcanic Area, Saudi Arabia, using remote sensing

Abstract

The Al-Ays Volcanic Area (AAVA) experienced a massive earthquake swarm in 2009 under the Harrat Lunayyir (HL). To examine the space distribution of basaltic lava flows in AAVA, we present here an analysis of satellite images. This has helped to identify three generations of lava flows within AAVA for the first time, their spatial extent and relationship to geological features. Various remote sensing treatments were applied to the Landsat 8 image: (a) color composites, (b) band ratioing, (c) principal component analysis, and (d) a mathematical index. Spectral analysis of the maps assists with charting the spatial configuration of the lava flows. Total area occupied by basalts is ~677 km2, of which the oldest lava flows occupy almost 52% (354 km2) and the lavas of intermediate age share 43% (295 km2) while the recent lava flows merely share 5% (28 km2), including 6.8 km2 referring to the volcanic cones. It should be noted that the generation of lava flows outlines a rather small area, of ≤20 km radius, circumventing the swarm epicenter zone. These maps may prove useful in volcanic hazard mapping for the rugged terrain.