Breakouts since September 23 have resulted from dams within the tube. The roof and walls of the tube cooled when the tube emptied following the intrusion on September 12. Rocks shrink and crack when they cool, spalling off the sides of the tube. Consequently piles of rocks formed at a number of places in the tube. When lava again entered the tube, it had to spill onto the surface upstream of a strong dam, forming breakouts.
Small flows spill out from the pond, building the banks of the pond higher.
As a result, the surface of the pond can rise, spill out again, and rise once more. Perched ponds formed at several places where breakouts took place since September 23. They form seemingly anomalous high areas on the otherwise gently sloping flow field. On a few nights, those lucky enough to be at the end of the Chain of Craters Road have been treated to long-distance views of glowing lava flowing down Pulama pali. A tripod and long-lensed camera are necessary to capture these scenes adequately.