WILKES-BARRE — You think “volcano,” you think steep cone with big opening spewing steaming orange lava that pours destruction rapidly downward.
You probably don’t think of sluggish black blobs with orange streaks crawling from a crack in your back yard lawn.
So what’s with all those sideways eruptions of Kilauea on Hawaii’s biggest island?
Geology professor Sid Halsor can give you a pretty good idea, and not just because volcano-related seismic activity is a specialty. He and some Wilkes University students hiked six miles one way to stand in the well-established — until recently — lava flow field of Kilauea in March, less than two months before the magma mass made national headlines.
“These kinds of volcanoes are referred to as shield volcanoes. They have a very broad profile, gentle slopes and a wide base,” Halsor explained. “It’s as if you set a shield on the ground.”
So while it still has the traditional summit that in other volcanoes is high and conical, that’s not always where the lava breeches the surface.
For years Kilauea actually erupted in a well-established field on one side of the summit. That’s where Halsor and some students visited in March. He has photos of them standing amid a mass of gray glop’s that look like someone randomly sprayed blobs and swirls of liquid foam insulation left to harden.
This is not the only layer of lava in the field, Halsor added. A volcano like this one spews lava that “is very liquidy and can flow over a long distance, forming a long, thin flow. We call it low-viscosity.”
That’s why the flows you often see on TV look more black or gray than that dramatic orange stuff you remember from, say, the eruption of Mount Doom in the final “Lord of the Rings” movie (you know: “I’m glad to be with you, Samwise Gamgee, here at the end of all things.”)
It’s also why Halsor and company could make the long trek to the field in March without fearing calamity. Even if the fissure starts pouring forth anew, odds are good you can outrun the threat. Thus all those news shots of reporters standing near the lava flow behind them.
Such flows can harden before the next eruption puts another layer on top, a process that can repeat itself many times. In fact, the recent eruptions that have come on the south side of the summit that forced thousands to evacuate and destroyed dozens of homes is not as new as one might think.
“In the 1960s, lava erupted near where it is currently erupting,” Halsor said. In fact the homes currently being destroyed probably sit above old layers of lava covered and long forgotten.
The big trick now, Halsor said, is to try to figure out what happens next. He noted the shift in eruption locations this year was not entirely unforeseen. Scientists noticed a surge of magma near the summit and the traditional lava field, then watched it drop, which usually would mean it found a different path of least resistance to the surface — proven when it spewed in the residential area known as Leilani Estates.
A big indicator of where the magma has moved underground can be seismic activity, Halsor said. The rise and fall of magma can prompt rock above to fall, or can bring it in contact with groundwater, creating sudden steam that breaks up rock and ejects it explosively.
“Geoscientists can do a pretty good job of tracking magma beneath the surface,” he said. “right now there isn’t any other place it is flowing that I’m aware of.”
Which means that, if things don’t change, the area being overrun thanks to more than 20 new fissures in the last month or so could become uninhabitable for a long time — turning into another lava field akin to the one Halsor and his students visited in March.
Either way, these days Kilauea is a geoscientist’s dream destination.
“For geologists, this is the best place on earth to study the relation between volcanoes and earthquake activity,” Halsor said.
Reach Mark Guydish at 570-991-6112 or on Twitter @TLMarkGuydish