“Much of the internet, phone systems, television and other high-speed communications relies on a world-girdling network of fibre-optic cables. By one estimate, more than 4 billion kilometres of such cables snake beneath and between cities; the longest ones span oceans. Normally, we don’t think much about this physical network, happy just to receive the calls, web pages and cat videos it transmits. Elsewhere, they are allowing researchers to measure the subsurface hum of London’s bustle, track the rumbling of Iceland’s volcanoes and map the upper reaches of our planet’s mantle. This new view of the underground has the potential to transform our understanding of the world’s constant vibration.”From New Scientist.