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Researchers link lunar cycles to eruptions

Scientists find tidal forces could predict volcanic seismicity, save tourists from eruptions

Senior Staff Writer
Friday, February 9, 2018

A recent study shows a likely correlation between volcanic seismicity and lunar cycles before an upcoming eruption.

“We were interested in investigating whether we could use the response of volcanic systems to tidal stresses to detect whether a volcano is in a critical state, or when it is about to erupt,” said Társilo Girona, a NASA postdoctoral fellow at the Jet Propulsion Laboratory and leader of the study. “These stresses vary with the relative positions of the moon, sun and earth, and from the study, we found that volcanoes are sensitive to tides related to the lunar cycles when they are about to act.”

The Ruapehu volcano in New Zealand was chosen as the subject of the study. Ruapehu is home to two ski resorts, and one of the main reasons it was chosen was because GNS Science, who supplied the data, had been studying it for over a decade in an attempt to ensure the safety of tourists on the volcano, said Christian Huber, co-author of the study and assistant professor of earth, environmental and planetary sciences.

The data provided by GNS Science was measured against a model of synthetic tidal signals linked to lunar cycles.

“The correlation we are looking at is whether volcanic activity responds to fortnightly tides, which are related to lunar cycles,” Girona said. “Out of the 12 years of data, we didn’t find any type of correlation between the two except three months before the only eruption (in the time span). There was a very significant statistical correlation.”

Prior to the study, there was no way to predict the eruption. “There were zero unrest signals, which is very troublesome because these eruptions can be very dangerous,” Huber said. Three months before the volcano erupted, its tremors synced with the tidal activity. If this correlation can be applied to more volcanoes, it can lead to greater eruption prediction capabilities, Huber added.

The data was also able to predict false alarms. “There were times where the mountain was closed because of an anticipated eruption, but no eruption took place,” Huber said. “These were points where the correlation between volcanic activity and tidal waves was very low, which is also cool to see.”

Girona and his team have already begun looking at other possible data sets to examine, hoping to produce similar results that could make these findings relevant in the future. The team is currently considering Costa Rica, the Philippines and Japan as possible locations for future studies, Huber said.

While the study’s replicability in other volcanoes remains to be seen, researchers agree that it has a great deal of potential for future use in eruption detection.

“If it turns out that this detection could be used generally, meaning other volcanoes also show the same correlations, tides could be an incredible detector for eruptions,” said Baylor Fox-Kemper, associate professor of earth, environmental and planetary sciences.“It’s an interesting paper. To say that tidal forces are changing things other than whether or not we can go to the beach, that part is very cool.”

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