Rescuers combing the peak of Mount Ontake have found more bodies, officials said Wednesday, bringing the death toll in Saturday’s unexpected eruption to 47.
The figure makes it Japan’s worst volcanic disaster in almost 90 years.
Precarious conditions at the summit have made the search an on-off effort, and other bodies may still be undiscovered.
Nagano Prefectural Police had said earlier in the day that the death toll had climbed to 48, but later revised the number to 47.
Japanese media reports have said up to 20 people remain unaccounted for, although local emergency services say a greater number have been reported missing.
Toxic gas billowing from the volcano’s vents and the risk of further eruptions have prevented rescue workers from reaching some of the corpses.
Around 1,000 troops, police and firefighters are helping the rescue effort, bringing down 14 of the bodies discovered on Sunday, but leaving 10 in place.
An official at Nagano Prefecture’s crisis management office said rescuers have used helicopters to bring the bodies off the mountain, the upper reaches of which are buried in ash and rock.
“We believe there are more people still missing, but we don’t know how many,” he added.
Hiking is popular in Japan, with mountain trails regularly promoted by tourist offices.
Tourism officials encourage trekkers to sign in and out to record their presence. But many ignore that advice.
“Usually only 10 to 20 percent of hikers register their names with authorities before entering the mountains in high season,” one local tourism association told the Asahi Shimbun newspaper.
At the time of the eruption, 327 hikers reportedly had registered to be on Mount Ontake.
Rescuers hope many of those who cannot be contacted simply neglected to let rangers know they were safe.Nagano Prefecture has posted a notice on its website calling for information about hikers on the list.
“We don’t know if there are people buried deep beneath accumulated ash,” a senior police official told the Asahi.
The local fire department said 71 people are missing, while a spokesman for Nagano prefectural police said it has received hundreds of reports of missing people.
Authorities cautioned that some of the individuals named likely were unconnected to the disaster.
The volcano erupted shortly before midday on a Saturday, when hundreds of people were on the mountain. Many made it down safely, but dozens were trapped on the peak as rocks and suffocating ash rained down.
Autopsies carried out on the first 12 bodies retrieved showed the cause of death was injury from falling rocks.
A sticky blanket of ash smothered the upper slopes. In some places, craters a meter wide suggested the violence with which rocks hailed down.
The roof of one of the huts near the caldera where hikers took shelter was punctured.
Since the eruption, volcanic tremors have continually jolted the peak as underground water boils into steam and breaks or shifts the rock underground, a volcanologist at the Meteorological Agency said.
The agency warned Wednesday the eruption was still underway, saying smoke had been seen rising from the volcano as of 9 a.m.
Until now, Japan’s single biggest death toll from a volcano had been 43, when Mount Unzen erupted in southwestern Japan in 1991.
In 1926, 144 people were left dead or missing after the eruption of Mount Tokachi on Hokkaido.