No casualties were immediately reported.
Another eruption on Friday evening had sent clouds of ash up to 10 kilometers high, illuminating the night sky with glowing lava and bolts of lightning.
The two eruptions happened in a span of less than five hours.
Lewotobi Laki Laki, a 1,584-meter volcano on the remote island of Flores, has been at the highest alert level since its eruption on June 18, and an exclusion zone has been extended to a 7-kilometer radius as eruptions became more frequent.
The Indonesian government has permanently relocated thousands of residents after a series of eruptions there killed nine people and destroyed thousands of homes in November.
Indonesia is an archipelago of more than 280 million people with frequent seismic activity.
It has 120 active volcanoes and sits along the “Ring of Fire”, a horseshoe-shaped series of seismic fault lines encircling the Pacific Basin.
