For the first time in recorded history, a pond of water has been discovered inside the summit crater of Hawaii’s Kilauea volcano. What happens when water and hot lava mix? Scientists aren’t exactly certain what comes next. But they do know that when lava interacts with water, the results can be explosive.
Researchers observed a mysterious green patch at the bottom of the volcano’s Halema‘uma‘u crater for a week. They confirmed the presence of water on Thursday, according to officials with the U.S. Geological Survey.
“The question is what does this mean in the evolution of the volcano?” USGS scientist emeritus Don Swanson says.
One possibility is that lava could slowly heat up groundwater and eventually create a new lava lake, Swanson says. Lava could also interact with the water table and create small explosions.
Yet another possibility is that the magma inside might rise rapidly. “That could produce a larger explosion,” says Swanson.
USGS officials stressed that there is currently “no reason to think hazards at the summit have increased or decreased” because of the water.
Kilauea has a history of alternating between long periods of explosive eruptions and times of slower, so-called effusive phases. Explosive periods are exactly what they sound like: centuries of massive explosions that send hot debris racing down hillsides and towering columns of rock and ash high into the atmosphere.
Effusive periods, one of which Kilauea has been in for about 200 years, are marked by slower, steady lava flows that—in comparison—trickle out of the ground. Researchers believe the next explosive period could be preceded by a massive collapse of Kilauea’s caldera (or crater) floor.
An eruption that was ongoing for more than 30 years came to a dramatic end last year when lava exploded from Kilauea’s flank. It covered a huge swath of land, destroying hundreds of homes in one of the largest eruptions in recent history. (See Volcano Forces Hawaiians Out.)
That eruption came with a significant drop of the caldera floor. Halema‘uma‘u crater collapsed nearly 2,000 feet over the course of several months. But Swanson says he expects an even larger collapse to trigger a prolonged explosive period.
Though researchers have never observed water on the caldera floor before, there are Native Hawaiian chants that describe the presence of ponds appearing just before explosive events.
“It’s really not scientific evidence but it nonetheless enhances the interpretation,” Swanson concedes.
(A small pond of green water can be seen at the lowest point of Kilauea volcano’s Halema‘uma‘u Crater in Hawaii. S. Conway/U.S. Geological Survey Hawaiian Volcano Observatory via AP Photos)