The White Island, known as Whakaari by Maori, is New Zealand’s most active cone volcano, according tomedia New Atlas. Between 1975 and 2000, it was in a state of continuous eruptions, the longest continuous eruption in history, and there were several other eruptions between 2012 and 2016. More than 10,000 people visit the island each year to experience its unique landscape, so the authorities are watching the signs of volcanic activity closely.
Although New Zealand authorities raised their alert levels in the weeks leading up to Monday afternoon’s catastrophic event, the catastrophic eruption on the Isle of Wight could not be accurately predicted because the hydrothermal fluid was driven by the expansion of super hot water that turned into steam.
For volcanologists, these eruptions can occur suddenly and almost without warning signs. On November 18, GeoNet, a Geological Disaster Monitor in New Zealand, raised the volcano warning level on the Isle of Wight to Level 2, citing an increase in sulphur dioxide output from magma deep in the volcano and an increase in volcanic tremors. “Conditions may include steam, gas, debris, and lava eruptions,” the authorities warned. These eruptions may occur without warning. “
GeoNet provided updates on 25 November and 3 December, maintaining a level 2 alert and both noting that “monitoring observations are similar to those observed during the more active period 2011-2016” and “recommendation sakaari/Isle of Wight may be entering a period of activity that is more likely than normal.” “
By monitoring the water level of the crater lake, the activity of gas and steam gushing from the active vents, and seismic activity in the area, volcano experts can identify clear signs of increased risk of eruptions. However, some types of volcanic eruptions have been shown earlier than others, and the underground response to the Isle of Wight tragedy is rarely warned.
“The types of eruptions on the Isle of Wight are called steam eruptions; they can occur in volcanoes around the world and may be relatively common. Sally Sennert, a geologist with the U.S. Geological Survey, explained to New Atlas. “When hot matter and water – groundwater and oceans or lakes – come into contact with each other, steam outbreaks or steam-driven eruptions occur. When magma interacts with water, steam eruptions are difficult to predict because there are few precursors, such as an increase in the number of earthquakes, and these precursors can be short-lived. “
Another example of a sudden and destructive steam eruption is the eruption of Japan’s Mount Mount Ontake volcano in 2014, which is estimated to have killed at least 50 hikers. There were no obvious warning signs, and subsequent investigations suggested that this was caused by a widespread rupture of underground rocks and a strong boiling groundwater.
A similar process is believed to be on the Isle of Wight in New Zealand. Shane Cronin, a professor of geosciences at the University of Auckland, described the cause of the steam eruption in This week’s “Conversation”, writing that volcanic magma can overheat water trapped in rocky pores and form an “active hydrothermal system.” “Water expands rapidly at supersonic speeds into steam, which is 1,700 times larger than the original water,” the professor wrote.
Cronin told New Atlas: “It looks like the shallow pipe system has accumulated gas to overpressure it. I suspect that liquid water and steam will be present at the same time at pressures above 250 degrees C (482 degrees F). These pressures are built on the crater’s filling and surrounding pores and cracks, and may be sealed by mineralization, clay formation, and possible sulfur fillers. The pressure rises below the seal until it suddenly breaks. “
There are many possible causes for rupture. The mixture of gases entering the pores and cracks may have changed, or it may be an earthquake. GeoNet did record a 5.9-magnitude earthquake on November 24 thin beneath the eastern part of The Bay of Plenty. This constant volatility is what makes predicting volcanic eruptions so difficult.
“It’s hard to see their build-up in any seismic record or other record, because these systems are very natural seismically active and varied in any case,” Cronin explains. The progressive nature of overpressure accumulation makes it almost impossible to discern. In contrast, magma eruptions show many earthquakes, as rocks break and extend to allow magma to rise to the surface. “
Oliver Nebel, an associate professor at the School of Earth’s Atmosphere and Environment at the University of Monis, explains that the slow and hidden accumulation of these liquid pressure banks makes steam-driven eruptions more unpredictable. “Because of the distance of the process, it is difficult to track mass movements inside the Earth, ” he says. Conventional monitoring relies on secondary effects, for example, if the magma volume increases or volcanic tremors increase when the magma is moving, it can swell. For fluids, there are virtually no of these auxiliary signals. The earthquake occurred only a few seconds or minutes ago. There is no way to make predictions or early warnings. What we do know is that volcanoes are active, so volcanic eruptions can occur at some point. “
The Lasca volcano in the Andes mountains of Chile experiences a natural eruption on average every two to five years. Around an eruption of this kind in October 2015, a team of scientists from Germany and Chile put together retrospective data from cameras and seismic, gas and temperature sensors to try to bring together events that would cause the eruption.
Scientists recorded several signs of volcanic eruptions, including increased seismic activity, fluctuations in sulfur dioxide levels, and heavy rains about 10 days before the eruption. “This precipitation event affected the gas in the crater and caused a brief eruption of stress that eventually led to the eruption,” the team wrote in the journal Natural Disasters and Earth System Science. Despite their rigorous approach to processing different data and benefiting from hindsight, the complexity of predicting these outbreaks is obvious.
“This study shows the chronological order in which steam-driven eruptions peak, and also shows that even thorough monitoring of volcanoes makes it difficult to predict the occurrence of steam eruptions,” the researchers wrote. “
“These systems are dynamic and all changes must be considered based on the past experience of each system,” Cronin said. In short, it is difficult to see whether surface changes equate to a higher risk of eruptions. “
As in the case of studies on the Rasca volcano and the Imperial Mountains, this could shed more light on how these eruptions occur and some things to be noted in the future. But Cronin noted that adding things like depth and pressure sensors to monitor volcanic systems such as the Isle of Wight is dangerous and “can trigger eruptions.” As a result, the prospect of more complex, real-time monitoring systems becomes unlikely.
“Instruments and modeling can be improved in terms of predicting these kinds of events, but predicting natural events is never perfect,” Sennert said. I often associate volcanic events with events that may be more familiar, such as weather conditions. Meteorologists can warn of tornadoconditions, but they can’t say with any certainty that they will form, and they certainly can’t say exactly how long the tornado will last and how it will go. “