Courtesy of state Land Department
A waterfall provides a deceptively peaceful backdrop
to rocks from Sunday's landslide.

---

Geologists say exact
cause unknown

Koolaus and other ranges
are susceptible to slides

By Craig Gima
Star-Bulletin

It may have been the weather -- the heat and lack of rain -- that caused a section of an old lava flow to give way. Or it may have been tree roots that cracked the rock and the wind that caused the roots to move back and forth until the rocks broke off and fell.

Geologists may never know the exact cause, but they do know that landslides happen in the Koolaus and other aging mountain ranges in Hawaii.

"These things happen. I won't say they're common, but they're not uncommon either," said Glenn Bauer, a geologist with the Department of Land and Natural Resources.

Bauer and other geologists examined the slide area by helicopter and on foot yesterday. He said the slide began about halfway down on the Kaneohe side of the cliffs that tower above Sacred Falls.

A section of an old pahoehoe lava flow about 15 feet across and only a few yards deep gave way, Bauer said. It wasn't much material, but it was heavy and the rocks traveled about 600 feet straight down a dry waterfall.

"It took out more debris as it moved downslope, and it got channeled into that chute area so it just came sort of like shotgunned down," he said.

"When it hit, it kind of exploded out," Bauer explained.

The debris was scattered over an area of about 60 square feet in the pool below the falls and over an area where people sunbathe.

Bauer said he found evidence that some rocks flew as far as 150 feet away from the impact area.

The area high above the falls is still unstable. Small rocks fell around Bauer and another geologist as they were surveying the damage.

Land Board Chairman Tim Johns said people that go hiking need to be aware of the possibility of landslides, but there is not much that can be done to prevent them.

"I don't know how well-educated someone could be sitting there and expecting rocks to fall from the sky," he said. "That is something that at some point you have to say that you're in the arms of nature and there are certain things you can control and certain things you cannot control."

He said it is unlikely Sacred Falls can ever be totally safe from landslides.

"Geologists are not magicians. They may not ever be able to ever say for sure whether it's safe and whether it's not going to fall again," Johns said.