Hawaii's Kilauea volcano just exploded

Hawaii's volcanologists got it right.

Although Hawaii's volcanoes rarely erupt explosively, a perfect stage had been set for such an eruption to occur this week, and it did. According to the U.S. Geological Survey (USGS), Hawaii's Kilauea volcano erupted explosively at 4:15 a.m. Hawaii time on Thursday morning.

An imposing ash cloud reached 30,000 feet into the sky, presenting danger to aircraft and potential respiratory issues for islanders, depending on where the ash lands.

There have been no reported deaths or injuries from the explosion.

The explosion occurred at the famous Halema‘uma‘u crater in the middle of Hawaii Volcanoes National Park, which was closed down over the weekend as scientists warned that the volcano could erupt explosively at any point, hurling ash, "lava bombs," and massive boulders into the air.

Another such eruption could happen at any point.

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"At any time, activity may again become more explosive, increasing the intensity of ash production and producing ballistic projectiles near the vent," the USGS wrote on their Volcano Hazards website.

The USGS released a preliminary simulation of where the volcano's ash might land, but notes it's "Not an official forecast."

Scientists expected an explosive eruption for a specific reason: A large lava lake had drained over the last week and a half, lowering some 1,000 feet beneath the crater's rim.

Once the lava dipped below the island's water table (the point at which the ground is saturated with water), this could allow water to seep uninhibited into the lava, creating lots of steam.

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The problem, however, is that the retreat of lava left a thousand of feet of vulnerable rocky walls without any support, and rocks started tumbling down into the depth of the vent.

Scientists warned that if these rocks plugged up the vent, steam-derived pressure could build up, stoking an explosion of ash, gas, and rocks. Now, this appears to have happened.

But unlike volcanoes that are expected to erupt explosively, this Kilauea eruption shouldn't be deadly, as long as people stay away from the vicinity and avoid ash-choked air.

Truly explosive volcanoes -- like Mount Vesuvius or Mount St. Helens -- can blast out speeding avalanches of scorching rock, ash, and gas. Called "pyroclastic flows," these are unquestionably and historically deadly.