Lava could be seen spewing out of the seventeenth fissure after two weeks of eruptions led to a major health hazard for the island's residents.
The activity from Kilauea has hit the tourism industry hard, with at least $5m (£3.7m) of cancellations for the three months to July.
Lava burnt through the rainforest on Tuesday and has come within two miles from pouring into the ocean, with evacuations widespread.
Balls of magma known as "spatter bombs" were sent 500ft into the air from a number of the fissures.
Fissure 17 opened over the weekend, while the US Geological Survey confirmed on Monday morning that the eighteenth had erupted.
Fissure 17 was the most voluminous, with estimates putting it at several hundred yards long.