Massive waves slammed a U.S. Army base. How it happened is mysterious. (original) (raw)

One or more probable rogue or sneaker waves slammed into a military site on the island of Roi-Namur in the South Pacific earlier this week, causing extensive damage and inundating structures with water several feet deep.

Viral video of the episode shows the forceful waves bursting into a dining hall, breaking down doors and causing several people to fall.

Roi-Namur is the second-largest island on the Kwajalein Atoll, which is made up of 97 small islands along a coral rim that encircles a small lagoon. Part of the Republic of the Marshall Islands, Roi-Namur is home to the Ronald Reagan Ballistic Missile Defense Test Site, as well as a small military facility.

The waves struck Saturday when the National Weather Service in Guam had issued a warning for high surf, but the magnitude of the waves appeared to catch its victims off-guard. One person was injured.

A statement from the U.S. Army confirms that “flooding from the waves damaged much of the unaccompanied personnel housing,” and notes that 80 of the island’s 120 inhabitants were evacuated elsewhere. Sixty people remained for recovery efforts to restore basic services.

“The dining facility, Outrigger Bar and Grill, the chapel and the Tradewinds Theater were moderately to severely damaged,” wrote the Army. “The automotive complex remains underwater.”

Debris also littered the island’s only runway, which FAA documents indicate sits at 14.4 feet above sea level. Recovery efforts will be slow until relief aircraft can safely land on the island.

“The efforts of the garrison and multiple mission partners, which is named Operation Roi Recovery, could take months to complete,” read the Army statement. “Aerial photos show extensive damage to Roi-Namur’s infrastructure, and multiple areas on the island are underwater.”

Were they rogue waves?

A strong low pressure system had been present in the North Pacific at the time. Though it was thousands of miles away, its influence on the oceans was geographically extensive. Weather models and the National Weather Service alike indicated the potential for 10 to 15 foot waves coming in on a swell from the north.

To answer whether they met the criteria for rogue waves, a few definitions must be established.

First, wave heightrefers to the difference between the crest, or peak, and trough, or dip, of a wave. A wave might be 15 feet from trough to crest, but that means it only reaches 7.5 feet above sea level, since the bottom of the wave is 7.5 feet below sea level.

A rogue waveis defined as a wave at least twice the significant wave height, which itself is defined as the average of the biggest third of all waves. It sounds like a lot of jargon, but the takeaway is this: rogue waves are twice as big as the tallest of the rest of the waves.

We can make a couple assumptions:

• Since debris was washed onto the runway, which is 14.4 feet above sea level, we can assume that the wave heightswere at a very minimum 28.8 feet. It was more likely in the 30 to 40 foot range, since it also penetrated over 300 feet inland to reach the Outrigger Bar and Grill.
• 30 feet would be more than twice the significant wave height at the time, meaning this wouldqualify as a rogue wave according to that definition.

Therefore, rogue waves appear to be a plausible explanation. Alternatively, AccuWeather posits they may have been “sneaker” waves, which are unusually high waves among a group of smaller waves. They’re similar to rogue waves in that they’re very large and hard to anticipate. However, rogue waves are said to occur over the open ocean whereas sneakers strike shorelines. In this regard, Saturday’s event may have met the height criteria for rogue waves but more neatly match the definition of sneakers.

Dangerous and sudden

Rogue waves are poorly understood, difficult to study and virtually impossible to predict. While some have been measured and detected in recent years — like the 100-footer observed near Newfoundland during the passage of Hurricane Dorian’s remnants in 2019 — many are undetected.

Until researchers can obtain a long-spanning data set from multiple locations documenting essentially every wave over a lengthy time interval, scientists won’t be able to ascertain where there exist flukes or oddities in distribution of wave heights. Are rogue waves simply rare but expected extremes that are bound to happen? Or are there other mechanisms at play that create them? Scientists have several explanations for how they might form.

Regardless of their cause, rogue waves can be damaging and deadly. On Nov. 29, 2022, the Viking cruise ship Viking Polariswas hit by a rogue wave while navigating to Ushuaia, Argentina. One person was killed, and the Antarctic leg of the itinerary was canceled.

While understanding of rogue waves remains elusive, scientists may be gaining greater insights into how sneaker waves form. Last year, researchers at Oregon State University published a study finding sneakers that strike the Pacific Northwest coast are generated by far-off storms and conditions just right closer to the coastline.

Jason Samenow contributed to this report.