One of the early hallmarks of this month's lava eruptions on Hawaii's Big Island was that the molten rock, though it destroyed homes and roads, generally didn't often ooze very far.
That could change soon, with scientists saying lava erupting in the Kilaeua volcano's rift zone could be even hotter, and therefore more runny.
Why? To start with, geologists think much of the magma oozing from the ground into the community of Leilani Estates since May 3 -- miles east of Kilaeua's summit -- may have been stored in underground channels in the volcano's rift zone since a 1955 eruption.
Rock samples and chemical analysis show the lava "so far looks to be similar to the 1955 lava chemistry," Tina Neal, the Hawaiian Volcano Observatory scientist-in-charge, told reporters Friday, according to CNN affiliates KGMB and KHNL.
That long-stored lava would be relatively cool, and would move slowly when it flows out of the fissures near Leilani Estates. But as that lava is getting cleared out, newer and hotter magma could be moving underground from the summit reservoir and replacing it, resulting in an eruption of hotter and runnier lava.
One analogy would be to honey -- it's going to be stickier when it's cooler and flow more easily when it's hot, said Erik Klemetti, a volcanologist and assistant professor of geosciences at Ohio's Denison University.
Cooler magma would be more sluggish -- in part because minerals such as olivine and feldspar will have formed in it.
"It might come from the source crystal-free, but as it cools, minerals will start to form," Klemetti said.
Hotter lava also could have more gasses dissolved in it, Klemetti said, which could lead to more lava spewing 100 feet into the air, like it did this week at one of the fissures.
The lava was flowing for hundreds of yards past that fissure. The observatory hasn't indicated that the composition of the lava has changed yet.
Earthquakes suggest magma still is moving into the rift zone, Neal and Klemetti have said.
"What we're all wondering ... is if it will take a turn for the worse in terms of hazards if fresher, hotter magma makes it to the surface," Neal told reporters Friday.