Radar images show changes to Kīlauea caldera floor

These radar amplitude images were acquired by the Italian Space Agency's Cosmo-SkyMed satellite system and show changes to the caldera area of Kīlauea Volcano that occurred between May 5 at 6:12 AM local time (left image) and May 17 at 6:12 AM local time (right image). Two small explosions from the summit eruptive vent occurred during that time period. The satellite transmits a radar signal at the surface and measures the strength of the reflection, with bright areas indicating a strong reflection and dark areas a weak reflection. Strong reflections indicate rough surfaces or slopes that point back at the radar, while weak reflections come from smooth surfaces or slopes angled away from the radar. Major changes between the May 5 and 17 images include: (1) a darkening of the terrain south of Halemaʻumaʻu crater, which may reflect accumulation of ash over the 12-day period between the images; (2) enlargement of the summit eruptive vent on the floor of Halemaʻumaʻu crater, from ~12 acres on May 5 to ~34 acres on May 17; and (3) the development of a small depression (area of ~15 acres) on the east rim of Halemaʻumaʻu crater that reflects slumping of a portion of the rim towards the growing collapse pit on the crater floor.