NEW DELHI — A deadly flash flood near Nepal's border with Tibet on Wednesday may have been triggered when the lower part of a glacier broke off and crashed on to the valley floor hundreds of metres below, experts said citing satellite imagery from Planet Labs. It was not clear what caused the glacier to collapse, but Nepali officials have pointed to an earthquake in the region minutes earlier as a possibility. Authorities on both sides fear the total number of casualties will be far higher than the nearly 100 bodies so far recovered. More than 300 travellers were missing, Nepal's government has said. Before-and-after satellite imagery of the region from Planet Labs, reviewed by Reuters, showed lush green mountainside now buried under brown debris and sediment. "It’s confirmed that a substantial portion of that glacier snout collapsed to initiate the event - probably including or entraining a fair amount of rock and sediment," said Vikram Gupta, who specialises in engineering geology and teaches at India's Sikkim University. Earth scientist Dan Shugar, an associate professor at the Uni