Following last week's eruption of Mount Moto-Shirane in Gunma Prefecture, both central and local authorities have come under fire for failing to issue a warning to climbers and skiers in the area until about an hour after the blast.

When a volcano erupts, the Meteorological Agency is supposed to issue an alert so people in the area can seek cover. Some experts blamed the tardy response to this incident on overly cautious officials.

The first alert "could just be that the volcano in question appears to have erupted. If they don't know, more information can be provided in a follow-up alert. They should have operated more flexibly," said Kazuhiro Ishihara, head of the Meteorological Agency's Volcano Eruption Prediction Liaison Council, which includes experts from both inside and outside the government.