Network of seismometers deployed in Iceland

Jon Lawson

Hekla is one of Iceland’s most active volcanoes. Scientists hope to use a network of seismometers to peer into the belly of the mountain and warn of an impending eruption. Connecting this network calls for an especially tough cable from LAPP, as the environment in the mountains of Iceland is anything but friendly. 

Scientists are in the process of installing an array of seismometers on top of Hekla in order to warn visiting tourists of imminent eruptions. “Hekla could erupt at any minute”, warned Martin Möllhoff, “and the longer this quiet period goes on, the more violent the eruption will be.” The German geophysicist works at the School of Cosmic Physics of the Institute for Advanced Studies in Dublin, Ireland. Here, he leads the technical division that uses seismometers to monitor countless volcanoes around the world, including Hekla. The scientists decided to use a cable from LAPP for transferring both the data and the power required to run the seismometers, which is generated by small wind turbines supported by solar cells. 

On the volcano, the cable has to be rolled out over razor-sharp rocks. It has to withstand mechanical abrasion and sub-zero temperatures which can occur all year round. The cable features four twisted pairs, surrounded by an aluminium-coated plastic band that acts as screening. The PE outer sheath resists UV light and is transversely waterproof, meaning that it does not allow moisture to penetrate through the sheath. If water penetrates at the ends of the cable, in this case at the connections to the seismometer and the modem in the data centre, or through a tear caused by a sharp object, the water is prevented from spreading. This is because the cable is filled with petroleum jelly, commonly known as Vaseline. 

At the same time, due to the volcanic activity the ground can be very warm and highly corrosive gases flow out in some places. 

The measurement campaign is planned to continue until the next eruption occurs. The goal is to gain insights into developing a permanent early warning system. Such a system could then also be installed on other volcanoes. At any rate, the research goes on. Möllhoff: “There are still plenty of volcanoes we have not explored yet, and plenty of unanswered questions.”