Emergency workers have been hampered by unstable ground since Tuesday, when a truck and its driver were swallowed north of Tokyo.
A fire department official said on Thursday that the hole had deepened, and that the front section of the truck, where the driver is believed to be trapped, was no longer visible. "The situation is extremely dangerous, and we can't send many rescuers," he said. "We will try to rescue him as soon as possible." Firefighters are considering the use of heavy machinery to clear the dirt and debris in order to access the trapped driver. On Wednesday, a large crane was able…