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Big Island break off causing Oahu tsunami sounds like a “poorly-written disaster movie,” BYUH professor says

Large blue wave in the ocean with blue sky.

A viral post from a 2018 Big Island Now article claims that the Kilauea volcano on the Big Island, which is slowly slipping into the ocean, could break off and cause a catastrophic tsunami to strike Oahu. BYU–Hawaii geology professor, Dr. Benjamin Jordan, weighed in.

“In the end, the statement sounds like a plot from a really poorly-written disaster movie,” said Jordan, a professor in the Faculty of Sciences.

The viral post, which has gained traction again on Facebook, discusses the possibility that a piece of land on the south side of Kilauea could break off and tumble into the ocean. This piece of land is known as the Hilina Slump and is roughly the size of Manhattan. Such a huge piece of land falling into the sea would generate, according to the claims investigated by Big Island Now, “a tsunami … with 100-plus foot waves moving at 500 miles [an] hour.”

Furthermore, the original claim from Big Island Now includes the assertion that the possibility of the Hilina Slump causing such a disaster has been deliberately covered up by the United States Geological Survey. “The bosses at USGS know about this and are intentionally concealing the information for fear of causing panic,” the original post said. “Media outlets have been told not to say anything about this possibility for the same reasons.”
In response to the viral post, Jordan said, “Why would anyone want to hide such information? It does not make any rational sense. If such an event were going to happen anytime soon, geologists and community leaders would be doing everything they could to warn people and develop hazard mitigation processes to protect people. That’s what geologists do. Anyone that has taken a geology class that discusses the Hawaiian Islands, including any of mine, knows about the potential for mega-tsunamis caused by landslide collapses of volcanic islands. There is nothing hidden about it. A simple Google search will turn up a load of information on the subject.”

The danger posed by the Hilina Slump is minimal. “The likelihood of it happening anywhere in the next 100,000 years is almost nonexistent,” Jordan said. “This [article] is from three years ago, and if anything, Kilauea, although erupting again, has settled down since then. It is following a pattern that has been occurring for at least the last 200 years.”

Oahu is no stranger to landslides or tsunamis. According to Live Science, 15 giant landslides have occurred in the Hawaiian Islands in the past 4 million years. The most recent one occurred on Oahu a staggering 100,000 years ago. As for tsunamis, a landslide triggered by the Mauna Loa volcano caused one which left telltale deposits on the Big Island 50,000 years ago.

According to Gary McMurty, a University of Hawaii professor who was interviewed by Live Science, these events happen every 100,000 years. He said it should be noted that the volcanoes that originally formed Oahu are no longer active because the shifting of the Earth has gradually moved the island away from the hotspot which creates volcanoes.
Jordan said, “There is potential for volcanic island collapse. … It is a potential that exists at all volcanic islands worldwide, not just Hawaii. While there have been small coastal collapses that have generated tsunamis [in the past 200 years], none have been mega-tsunamis. All have had limited local impacts, although some led to tragic deaths.”

A list of mega-tsunamis compiled by PBS NOVA noted that the two most recent ones, in Chile in 1960 and the Indian Ocean in 2004, were caused by massive earquakes.