Experts: Diamond Head landslide could happen again

The road is open, but crews are still keeping a close eye on a hillside along Diamond Head Road. That’s where a retaining wall came crashing down on Tuesday.

Contractors say the concrete wall was built before 1930 and had no rebar in it, meaning it didn’t have any extra reinforcement

“At this point, it’s up to the property owner to further stabilize that hillside and ensure that whatever structures are on top are going to be safe and not going to impose a danger to the public,” said Ross Sasamura, Department of Facility Maintenance director.

Landslides like this are not all that unusual.

“The steep slopes, the layered fractured volcanic rock, the large amounts of precipitation, the nice, warm climate that we enjoy, contributes to the rocks breaking down more readily,” University of Hawaii geology professor Dr. Steve Martel said.

Dr. Martel says plants on the hillside can actually contribute to land or rockslides when their roots dig down into the rocks.

The city took away five truckloads of debris after this slide. Who pays the bill?

“And as far as the city is concerned, at this point, the efforts that we have expended to date so far in cleaning up the roadway, we’ll be seeking reimbursement for that,” Sasamura said.

If in the future more debris ends up on Diamond Head Road, the property owner will be responsible.

“The best option for the property owner is to seek the proper advice from registered professionals, get an engineer that can actually look at it, and make recommendations and then proceed according to those recommendations,” Sasamura said.

Dr. Martel points out that situations like this represent a force of nature.

“There will be landslides and rock falls out here without any human involvement whatsoever. It’s just that in many cases when we build houses or put roads in, now we’re entering into this geologic environment and we can affect it,” Dr. Martel said.

In the meantime, property owners living on a hillside should be aware of their obligations in the event of a rock fall like this.

Related story: Diamond Head Road reopened after retaining wall collapsed

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