A breakdown of the catastrophic

Rescuers are struggling to reach around 100 people believed to be trapped alive in tunnels across Nepal's hydroelectric power network. It's been almost a week since some of the tunnels were buried under meters of mud when a glacier collapsed, triggering landslides and floods. Some of the hydropower workers managed to escape the tunnels, but officials say more than 900 hydropower workers are still missing. DW spoke to international tunnelling expert Arnold Dix, who is advising the Nepali rescue efforts from his base in Melbourne, Australia. He says there is no blueprint for such a challenging rescue. The first challenge is trying to locate the tunnels, after all above-ground markers have been swept away.