Why can’t volcanic eruptions be warned in advance?

The eruption of the New Zealand volcano caused many injuries. Whether any of them were Chinese nationals has become one of the questions we are most concerned about. The ensuing question is why there was no warning for the eruption of the White Island volcano? If you are also particularly interested in tourism, you should know that as early as 1953, White Island in New Zealand became a scenic reserve that attracted a lot of attention. Therefore, many tourists from other places often go here. Enjoy the scenery.

Although the volcanic eruption was classified as medium-sized by the New Zealand Seismological Monitoring Agency, its alert level has been raised to level four. Moreover, through the inspection of aerial reconnaissance aircraft, no signs of life activity were found on the White Island. This means that the volcanic eruption caused at least dozens of injuries or even direct deaths. So, why did the volcano on White Island suddenly erupt, and the people on the island did not receive any warning messages before the incident?

Why did a volcanic eruption occur suddenly on White Island?

As we all know, the geological phenomenon of volcanic eruption at any place is nothing more than the release of thermal energy inside the earth, and is accompanied by strong events on the surface. form of expression. The tourist attraction called White Island in New Zealand is about 48 kilometers away from the north east coast of New Zealand.

Although its appearance looks like a horseshoe, it is actually the most active volcano in the country composed of three volcanic cones. Just in the historical records, the volcanic cones have records of eruptions with temperatures reaching 800 degrees Celsius, and the floors of these craters have long been covered in volcanic ash. This is why this island was also rich in sulfur mines.

Although this is a popular tourist destination, no local residents live here because White Island is one of the volcanoes in New Zealand that may erupt at any time. Due to the shallow location of the magma, the gas and heat emitted have a significant impact on groundwater and even surface water, and a powerful hydrothermal system has already been formed around it.

Why was there no timely warning before the White Island volcano erupted?

In the powerful hydrothermal system of White Island, the higher temperature water is trapped in the pores of the rocks. It also caused the volcano to erupt due to the steam generated during the process. Moreover, such a submersible eruption, or a hydrothermal eruption, is inherently sudden, and there is almost no time to obtain effective early warning information. Many people may not understand that when water expands, it turns into water vapor.

When the speed of this transformation exceeds the speed of sound, the current volume of the liquid is approximately 1,700 times its original volume. Such changes will undoubtedly have catastrophic effects on other things. Even rocks that normally seem to be extremely hard will be shattered into ashes and gravel under its huge expansion energy, and erupted hundreds of meters into the distance.

Moreover, before the White Island Volcano erupted, experts from the New Zealand Geological Hazards Organization had already warned that the White Island Volcano had been experiencing obvious abnormalities for several weeks: From the existing observation data It seems that the White Island Volcano may be more likely to erupt than in the past! However, after such a reminder was issued, it did not attract much attention and did not prevent any tourists from visiting the island.

And, just as earthquake early warning is difficult to achieve, achieving early warning through volcano monitoring is itself very challenging. And we still know very little about the triggers for such events. When such a disastrous event occurs, with our current level of science and technology, warning information can only be obtained within a few seconds to minutes at most.

We can indeed learn about the underlying vapor and liquid pressures in hydrothermal systems by tracking them and learning from their behavior beyond criticality. But because every hydrothermal system is so different, there are no simple rules to follow from studying a single volcano.

Although it seems unreasonable to be unable to provide early warning for volcanic eruptions in this era, the essence of volcanic eruptions is not caused by magma. Therefore, our existing detection system is still difficult to track the exact time of volcanic eruptions caused by water vapor. Many fatal hydrothermal disasters caused by volcanic eruptions have occurred around the world, such as the Ontake eruption in Japan in 2014.

What are the characteristics of different stages of volcanic eruption

Volcanic eruptions are not instantaneous events, but go through a relatively replicated staged process. In fact, there are different stages in volcanic eruptions, including gas explosion, formation of eruption column, collapse of eruption column, etc.:

The first stage: gas explosion, when the volcano is still erupting During the gestation stage, earthquake swarms and gas exsolution led to violent gas explosions in the fracture density zones of the overlying rocks. The rock becomes fragmented as a result, and the channel for the volcanic eruption is opened. Therefore, these rock fragments are the first to be ejected by the volcano.

The second stage: the eruption column is formed. When the volcano ejects gas during the gestation stage, its huge ejection force causes the rock fragments and magma in the channel to be ejected high into the sky.

The eruption column formed after the gas explosion is divided into a gas rush zone located at the lower part of the eruption column (one-tenth of the height of the eruption column), a convection zone located above the gas rush, and a diffusion zone located at the top of the eruption column. Three districts.

The third stage: the collapse of the eruption column. Due to the existence of gravity, the debris carried by the eruption column will collapse from different heights, and the speed of their collapse mainly depends on: volcano The size of the mouth radius, the content of rock debris in the eruption column, the amount of solid rock in the eruption column, and whether there is surface water in the eruption column.

When a volcano erupts, it will be accompanied by violent ejections of ash and hot rocks, and the moisture-filled ash will radiate hurricane-like coarse particle airflow from the explosion vent. Although violent eruptions of volcanoes are short-lived, once such an eruption occurs, it means that the volcanic system here needs to be re-balanced. In short, further eruptions are possible, although they are usually much smaller than the first, and eruptions are not uniform.