(BIVN) – Several small to medium-sized rockfalls were recorded at the Kilauea volcano summit lava lake in recent days.

Much of the large ledge that had built up on the south side of the summit vent within Halema‘uma‘u fell into the lava lake on September 8. That day, USGS Hawaiian Volcano Observatory scientists say rockfalls happened at 11:06 a.m., 12:16 p.m., 3:12 p.m., 6:06 p.m. and 6:12 p.m. HST, and another occurred at 5:10 a.m. HST on Sept. 9.

Such rockfalls are common during significant drops in the lava lake level, scientists say, because support is removed from the crater walls.

On Tuesday, USGS published some photos of the rockfalls. The photo seen above came with this caption: