HAUULA, Hawaii - The managers of Hawaii's state parks are turning to social media to counter online photos and statements encouraging people to visit a waterfall where a landslide killed eight people more than 15 years ago.

Signs warning people not to enter and trespassing citations haven't been keeping people away from Sacred Falls, said Curt Cottrell, assistant administrator for state parks at the Department of Land and Natural Resources.

So the state uploaded a video clip on Vimeo explaining why the area is off limits. It then posted the video on its Facebook and Twitter accounts to spread the word.

"We're essentially fighting fire with fire," Cottrell said. "Conventional methods of getting the word out about what's open and closed aren't working."

Sacred Falls is about an hour's drive from Honolulu on Oahu's lush eastern side. A park there used to be open to the public, but the state Department of Land and Natural Resources closed it in 1999 after boulders came crashing down on dozens of hikers.

Witnesses at first mistook the roar they heard for a flash flood. Instead, a chunk of the upper cliffs had slid down to the base of the falls, where people were sitting and swimming.

More than 50 people were injured, in addition to the eight killed.

The department has since posted signs warning about flash floods and rock falls at the park entrance and along the old trail. Signs note it's illegal to enter and that the fine for trespassing is $2,500. Even so, law enforcement officers issued more than 120 citations for trespassing last year.

Officials estimate about 40 to 50 percent of the citations are issued to travelers visiting Hawaii.

Officers say hikers tell them they read about the waterfall online.

Many web posts note the hike is illegal and warn about the fines, yet they also detail the waterfall's beauty.

One review at alltrails.com described Sacred Falls as "probably the most beautiful waterfall that I have ever seen."

But Guy Chang, the Oahu branch chief of the state's conservation enforcement division, said people who hike the trail put emergency response personnel at risk.

"If you're up there and injured, we're going to have to go in there and get you out," Chang said.

Firefighters responded to 911 calls from the trail once last year and three times in 2012, said Honolulu Fire Department spokesman Capt. David Jenkins.

Coty Gonzales, the founder of Exploration: Hawaii, a website that has chronicled over 100 trails on Oahu, said he removed directions to Sacred Falls on his site. Readers now see the department's video instead.

The 33-year-old psychology lecturer said the state should try to move its page up the Google search rankings and monitor the #sacredfalls hashtag on Instagram to further its social media campaign.

"It's natural to want to share what you're seeing, and social media makes that very easy. But then it's also very easy for novice hikers to think that they might be able to access and do the same hikes, which might be very dangerous," Gonzales said via email.

Sacred Falls is just one of several outdoor sites in Hawaii that are closed to the public but that are reviewed on social media sites. Online reviews direct hikers to climb Haiku Stairs - an Oahu trail that's also dubbed "Stairway to Heaven" - at night to avoid security guards posted there during the day.