People in Japan hoping to predict the next big earthquake should ignore mysterious deep-sea fish after experts said rare sightings of the creatures on the country’s beaches did not, as some had believed, foretell a seismic calamity.
University researchers said they had debunked the theory of oarfish as a harbinger of doom by comparing sightings of deep-sea fish, including those caught in fishermen’s nets, with earthquake records going back more than 90 years.
“We thought that if we could understand the connection, it would be useful for disaster prevention,” Yoshiaki Orihara of Tokai University’s Institute of Oceanic Research and Development said.
The experts, however, found no correlation between the sightings and major earthquakes.
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They uncovered 363 reported sightings since 1928 of oarfish and seven other species of deep-sea fish that have long been associated with earthquakes, while there were 221 earthquakes of magnitude 6 or greater over the same period.
But the team, whose findings were published in the Bulletin of the Seismological Society of America, discovered that just one of those quakes – in July 2007 – had occurred within 30 days of a fish sighting and within a 100km radius.
“It was disappointing to find no correlation, but we also want to investigate any connection between mass beachings of dolphins and whales with earthquakes in the future,” Orihara told Kyodo.
The oarfish theory’s roots lie in Shokoku Rijin Dana, a collection of mystery stories published in the 18th century that makes a connection between deep-sea fish and seismic activity.
Some experts have speculated that the creatures move to shallower waters when they sense electromagnetic changes caused by tectonic movement related to active faults, fuelling the popular belief that beached oarfish are an omen.
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Several sightings of oarfish, whose dorsal fin runs the entire length of its body, on beaches or in stationary nets sparked fear of impending disaster earlier this year.
While Japan’s early-warning system typically gives people several seconds to take cover before the arrival of a major earthquake, there is no proven method of predicting when tectonic plates will shift.
Some experts believe there is a 70% to 80% chance that a large area of Japan’s Pacific coast will experience a catastrophic earthquake within the next 30 years, with worst-case scenarios putting the death toll at more than 230,000 – more than ten times the number of deaths in the March 2011 earthquake and tsunami in the country’s north-east.