Mount Etna erupting. Tomarchio Francesco/Shutterstock

How can we inform when a volcano goes to erupt? – Lena, aged eight, Frankfurt, Germany

Predicting when a volcano may erupt could be very troublesome. Some volcanoes erupt virtually always, akin to Kīlauea on Hawaii, however others could have gaps of lots of of 1000’s of years between eruptions.

However we’re significantly better at prediction now than we have been 20 years in the past, because of new or higher developed methods.

Firstly, it’s essential to understand how every volcano has acted up to now, as every behaves otherwise. Scientists referred to as volcanologists work this out by wanting on the supplies which have erupted from the volcano up to now.

If a volcano erupted gently, it will create lava flows, that are streams of molten rock. These cool and solidify to type sheets of laborious rock. Different volcanoes create explosions once they erupt. These explosions produce fragments of rocks, crystals and volcanic glass (molten rock that has cooled in a short time on the floor).

Volcanic glass.

steve estvanik/Shutterstock

Finding out these supplies may help volcanologists perceive how violent the eruptions have been, and the way typically the volcanoes explode.

Volcanologists can predict if a volcano is about to erupt by utilizing a number of methods. The floor of the volcano could get hotter, because the magma – the molten rock underground that pours out as lava when a volcano erupts – strikes nearer to the floor earlier than an eruption. This may be monitored by detectors on satellites that measure warmth.

Wanting from area

The floor of the volcano might also be lifted up or dropped down resulting from motion of magma beneath the floor. This may be detected on the bottom, however may also be measured from area by satellites utilizing radar.

Radar detection of volcano motion works by finding out any modifications within the time taken to bounce radio waves from the satellite tv for pc to the volcano and again once more. The time might be shorter if the volcano has been lifted up.

Monitoring volcanoes from area is now quite common. It’s safer and cheaper than having volcanologists on the bottom close to the volcano being studied, significantly whether it is erupting or in a really distant space.

Flowing lava.

Yvonne Baur/Shutterstock

One other method of discovering out when a volcano is about to erupt is by measuring the gases escaping from it. It’s because when magma strikes in direction of the floor, fuel escapes and rushes out forward of the magma. These gases could be measured from area or on the bottom. If the combination of gases coming from the volcano modifications, this will point out that the magma beneath is shifting.

Shifting magma

Volcanologists additionally generally use two different strategies to see if a volcano is about to blow. When magma strikes it shakes the land, creating a sort of earthquake referred to as a harmonic tremor. These tremors can point out how briskly and the place the magma is shifting.

A second methodology that may detect magma motion is gravity measurement. Gravity is, after all, the drive that stops the whole lot flying off the floor of the Earth into area. However the energy of that drive truly decreases barely if the floor beneath your ft turns into much less dense.

Curious Children is a collection by The Dialog that provides kids the possibility to have their questions concerning the world answered by consultants. When you have a query you’d like an knowledgeable to reply, ship it to curiouskids@theconversation.com. We received’t be capable to reply each query, however we’ll do our best.

This doesn’t imply you’ll all of the sudden fly into orbit, because the modifications are tiny, however they are often measured by devices referred to as gravimeters. Molten rock has a decrease density than when it’s stable, so areas of decrease gravity on a volcano, significantly if they modify over time, may point out magma – and the opportunity of an eruption.

By finding out a volcano’s previous historical past and mixing data from many alternative floor and area methods, we could be fairly assured that we’ll get it proper and be capable to challenge warnings in good time to the those who reside close by, earlier than the volcano erupts.

When sending in inquiries to Curious Children, be sure to embody the asker’s first title, age and city or metropolis. You may:

electronic mail curiouskids@theconversation.com

tweet us @ConversationUK with #curiouskids

DM us on Instagram @theconversationdotcom

Ian Skilling doesn’t work for, seek the advice of, personal shares in or obtain funding from any firm or organisation that will profit from this text, and has disclosed no related affiliations past their educational appointment.