Interferometric Synthetic Aperture Radar (InSAR) images of Kīlauea (left) and Mauna Loa (right) spanning the past several years. Concentric patterns of colored fringes indicate magma accumulation centered near the summit calderas of both volcanoes. InSAR is one of several techniques used by the USGS Hawaiian Volcano Observatory to track deformation of active Hawaiian volcanoes.
