New Zealand scientists find tremor link that could predict volcanic eruptions | Volcanoes

Researchers in New Zealand develop a new warning system that monitors the tremor in volcanoes and can one day report whether an eruption is more likely in two to four days.

After the deadly The eruption of Wakaari in 2019researchers from the University of Canterbury have decided to determine whether the patterns of seismic frequency (shocks felt in the volcano) can help predict eruptions and prevent deaths.

Dr. Alberta Ardid, PhD in Natural Resources, Dr. Alberta Ardid studied GeoNet seismometer recordings – a tool that measures ground noise and vibration – up to 18 eruptions of six active volcanoes around the world, including three in New Zealand; Ruapehu, Tongarira and Wakaari.

The machine learning algorithm allowed Dr. Ardid to review thousands of records and highlight certain frequency patterns that occurred regularly before the eruption.

Conclusions that are published in Nature Communications, showed that three weeks and then a few days before the eruption there were similar changes in frequencies in some volcanoes.

The tremors became slower, indicating that there was a blockage in the shallow part of the volcano and that a seal or cap had formed that traps hot gas, creates pressure and sometimes causes an explosion.

“In our experience, this pattern began to manifest itself about three weeks before the eruption, and peaks about two to four days before the event,” Ardid said.

“However, it is important to note that we observed this sealing mechanism without any eruptions,” he said. Sometimes the pressure will passively drop, and other times it can explode. “That’s when it’s dangerous.”

The study found that Mount Ruapehu, an active volcano on the country’s North Island, shows signs of seal formation, Ardid said. “At this point we can say that the eruption will happen much more.”

Strong earthquakes have become more frequent in the last month, hot gas and liquid enter the crater lake, and sulfur spots appear on the gray water of the battleship near Mount Ruapehu. GeoNet, which monitors New Zealand’s geological hazards, has issued a warning of intensifying volcanic waves, saying activity over the past four weeks is “the longest period of earthquakes in 20 years.” It is impossible to predict whether a volcano will blow – unrest does not always lead to an eruption.

There is no tool for the final prediction of a volcanic eruption. As Ardid says, “The Holy Grail of Volcanology is trying to predict when an eruption will occur.” But what this study does allows scientists to more accurately determine the probability or probability of an eruption.

The study’s co-author, Dr. David Dempsey, a professor of civil and natural resources at the university, said that once the warning system passes a sufficient number of tests and scientists are confident enough about its level of accuracy, it could be used worldwide. .

Dempsey hopes they will be able to bring the tool to a stage where scientists can say the probability of an eruption in the next 48 hours is 10-20%. “It will be considered a very, very high level of confidence.”

Determining the relative risk of an eruption is very important – for example, to determine whether there is a probability of an eruption of one in 10 compared to one in 1,000. “With this information, you may or may not decide to postpone your visit to the mountain.”

New Zealand has 12 active volcanoes, and in many cases, including Mount Ruapehu, is a popular tourist destination or bordering residential areas.

“Active volcanoes, including Wakaari, Ruapehu, Tongarira and others around the world, where visitors and skiers are likely to be nearby, are unpredictable and sometimes dangerous,” Dempsey said. “Early warning systems can save lives and avoid debilitating injuries.”