Application | Volcano

WATERTIGHT IN EVERY DIRECTION On the LAPP website, Bergsson found an outdoor cable for connections in telecommunication. The cable features four twisted pairs, surrounded by an aluminum-coated plastic band that acts as shielding. The PE outer jacket resists UV light and is transversely waterproof, meaning that it does not allow moisture to penetrate through the jacket. If water penetrates at the ends of the cable — in this case at the connections to the seismometer and the modem in the data center — or through a tear caused by a sharp object, the water must be prevented from spreading through the cable. This is achieved by the petroleum jelly filling. Möllhoff thinks the choice of cable is a very good one. The 60-volt direct current power supply to the seismometers is stable, as is the data transmission in both directions via separate wire pairs. This allows the volcanologists to adjust the seismometer settings from afar. The measuring system for the first installed seismometer works perfectly; collecting 1.5 gigabytes of data per month and transmitting it live to Reykjavík and Dublin. UNTIL NEXT TIME... So far, there is nothing to suggest that Hekla might be about to erupt. The measurement campaign is planned to continue until the next eruption occurs. The goal is to discover how imminent eruptions are reflected in the measurement data and to provide 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. Martin Möllhoff: “There are still plenty of volcanoes we have not explored yet and plenty of unanswered questions.”

The conditions at the summit of Hekla roughly 4,800 feet above sea level, place special demands on the material.

the three kilometers of cable they needed for their entire installation. The main selling feature 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. Snowfall can also occur all year round. Another important factor is heat; here, above the thin crust of the Mid-Atlantic Ridge, the rock can get very warm. Geophysicists have already measured temperatures of 90° Fahrenheit at a depth of just 19 inches. To complicate matters further, highly corrosive gases flow out of the ground at some places. On the positive side, this inhospitable landscape is not home to any voracious animals that could gnaw away at the cable. The job of selecting the right cable fell to Bergur Bergsson. The engineer from Iceland’s meteorological office went looking for a petroleum jelly- filled Ethernet cable with four twisted-pairs, shielding, and a robust outer jacket. Bergsson’s colleagues have been using these cables in seismic measurement networks for 15 years, such as in a similar project on Vatnajökull, Iceland’s largest glacier. The decision to choose LAPP was above all thanks to the company’s website search function. “We were able to find exactly what we were looking for,” says Bergsson. “LAPP is also a very trustworthy brand in the cable sector.”

The Hekla volcano in southern Iceland. Source: Hansueli Krapf - Own work: Hansueli Krapf (User Simisa) Shared under Creative Commons CC BY-SA 3.0

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