You cannot stop a volcanic eruption, but you can predict it. Hekla is one of Iceland’s most active volcanoes. Scientists use a network of seismometers to peer into the belly of the mountain and warn of an impending eruption. The system uses extra-robust cables from LAPP. This is because the conditions in the Icelandic highlandsare anything but hospitable.
Reaching the peak of the volcano is a challenge for both man and material. The volcanologists’ equipment, including 3,000 metres of cable from LAPP, had to be transported through snow and ice to one of Iceland’s most dangerous volcanoes. When Hekla erupts, it spews a fountain of ash up to 30 kilometres into the sky. But since the last eruption in 2000, the volcano appears to have been on a break. This may be good news for tourists, but geophysicists are nervous.
A member of Martin Möllhoff’s team during the installation of the seismometer.
In the Middle Ages, people thought this was the gate to hell. Hekla is the centre of a volcanic crevice that stretches for 40 km and is at least 6,600 years old. Recently, the volcano has erupted around every 10 years: in 1970, 1980, 1991 and 2000. There are currently no signs that another eruption is imminent.
“The longer this quiet period goes on, the more violent the eruption will be”, warns Martin Möllhoff. The German physicist leads a team that monitors volcanoes around the world, including Hekla. If his probes detect minor tremors in the ground, it is red alert, as an eruption could be just 30 to 80 minutes away. That is why all visitors to Hekla must download an app to their smartphone that receives warning messages via SMS.
Detecting the warning signs
Near the crater, Möllhoff’s team has installed six seismometers that each contain a mass made from a thermally stable metal alloy. Tremors in the ground cause the housing to vibrate, while the mass does not follow the motion due to its inertia. This allows the team to detect movements measuring just millionths of a millimetre.
View of the seismometer.
As Hekla offers so little warning time, it would be impracticable to save these measurement values in the seismometer and take readings on site every few months as usual. Instead, they must be communicated immediately. This usually occurs via wireless. But in the gloomy Icelandic landscape, there is not enough sunlight for a solar-powered wireless modem.
That is why Möllhoff’s team decided to use a cable from LAPP to transfer the data. This cable also transfers the energy required to run the seismometer, which is generated by a small wind turbine. The scientists were able to order the precise length of cable they needed to cover the distances between the wind turbine, data transfer centre and the seismometers across the entire installation.
The main argument in favour of the LAPP cable was its robustness. The hard volcanic stone makes it impossible to install a cable underground, meaning it has to be rolled out over razor-sharp rocks. Here it has to withstand mechanical abrasion and sub-zero temperatures in the Icelandic winter, as well as highly corrosive gases from the rock and even snow in the middle of summer, or heat. Geophysicists have already measured temperatures of 50 degrees Celsius at a depth of just half a metre.
The cable was supplied by Johan Rönning, the market leader for electrical equipment in Iceland. Johan Rönning imports and sells LAPP products in Iceland, and supplies electrical components to most geophysical installations. The company has been working with LAPP since 1985. “We are very happy with the cooperation”, says Óskar Gústavsson, key account manager at Johan Rönning. Gústavsson praises the excellent support from LAPP’s experienced experts: “They’re also fantastic with delivery times”.