By early May, the lava flow was between and in height. It averaged more than and in some places was as much as thick. The flow carried off large blocks from the main cone that had broken off, as well as volcanic bombs. "The viscosity of the lava fragments ejected by the blasts was, for basalt, relatively high. Very little spatter was produced and scoria bombs sometimes broke up explosively in flight (presumably due to rapid vesiculation), and by rapid impact on landing." The high viscosity led to a "massive, blocky aā lava flow which moved slowly but relentlessly toward the north, northeast, and east."