NAGAOKA, Japan — Prime Minister Junichiro Koizumi walked along crumbled mountain roads yesterday to inspect collapsed homes and speak to survivors yesterday as he surveyed the damage inflicted by Japan’s deadliest earthquake in nearly a decade.

The death toll rose to 31 as elderly victims died from the effects of the weekend quake.

Aftershocks rumbled across largely rural Niigata prefecture, about 160 miles northwest of Tokyo, where a magnitude 6.8 earthquake struck Saturday evening, buckling roads and unleashing landslides.

Another 5,000 residents entered public shelters amid fears the aftershocks would trigger more landslides, raising the total of evacuated people to more than 103,000. Thousands more camped out in tents and cars, too afraid to return home.

With many roads still blocked off by landslides, relief workers and troops in helicopters and cars struggled to get emergency goods to isolated hamlets and overcrowded evacuation centers.

As of yesterday evening, 28,500 households lacked electricity and 45,000 did not have running water.

Recovery efforts moved forward in some areas. The Hokuriku highway, a major thoroughfare running through Nagaoka, reopened late Tuesday after being repaired.

The Niigata government launched plans to build temporary homes in Nagaoka by year’s end for those who lost their homes, said Nobuyuki Kondo of Nagaoka city hall.

The housing should accommodate 2,200 people from the nearby village of Yamakoshi, which was almost completely wiped out in the quake, as well as thousands left homeless in Nagaoka, Kondo said.