U.S. GEOLOGICAL SURVEY, HAWAIIAN VOLCANO OBSERVATORY Hawaiian Volcano Observatory geophysicist Jim Kauahikaua examined a volcanic hornito on January 25 in the area of the Puu Oo cinder cone. The spires were created by the spattering of lava propelled by gases.

Tower of Power

Mother Nature's rare
lava sculptures grace the
Big Island and reach skyward

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By Rod Thompson
rthompson@starbulletin.com

HILO >> In the lava wasteland surrounding the Puu Oo eruption area, a handful of chimneylike spires have risen in the last month.

Geologists call them hornitos, a Spanish word meaning little ovens. Inside these ovens, lava is cooking.

Hawaiian Volcano Observatory geologist Christina Heliker grew poetic in her description of how these pipelike stacks of lava grew over crusted lava rivers called tubes, starting in January.

"The hornitos quickly attained heights as great as 8 meters (26 feet) and assumed fantastic shapes -- tall, narrow spires and shrouded-monklike figures that provide a three-dimensional Rorschach test for bemused scientists," Heliker wrote.

Besides the shapes, the scientists were also bemused by their cause. The general process is understood, but no one knows exactly how the structures form.

Hornitos are formed when a lava tube fills and the lava has enough gas to make it spatter in a given spot.

"We hear the gas. It sounds like it's going to spit something up," said geophysicist Jim Kauahikaua.

No one has seen the spatter being deposited, he said.

A somewhat similar formation is a spatter cone, said Don Swanson, scientist-in-charge of the observatory.

But spatter cones have "roots," Swanson said. Their lava comes from a vertical magma source below the old ground level, and they tend to be bigger.

Hornitos are "rootless." They are created by horizontal lava movement near the surface.

Some crumble soon after they are formed.

"These are fragile features," said Hawaii Volcanoes National Park ranger Mardie Lane.

But they can also be sturdy. One went through a fairly strong earthquake without damage, Kauahikaua said.

Four or five dot the area now, the largest in number and size since the eruption began in 1983, Heliker said.

The hornitos site in the national park is technically open to the public, but remote and dangerous, Lane said.

"It would be most unwise to venture into that area," she said.

Instead, people can get an easy view of a 3-decade-old hornito just off Chain of Craters Road, about halfway to the coast, Lane said.