By Sophie Knight
TOKYO (Reuters) - When Toshitsugu Fujii became head of a Japanese task force on disaster response at Mount Fuji, he was confronted with a startling oversight. Japan had no plan in place to deal with a disaster in which an earthquake sparks a volcanic eruption at the country's most famous landmark.
Fujii said a tremor "greatly increases" the chance of an eruption in a country that has experienced nearly 12,000 earthquakes since the magnitude 9.0 tremor that led to disaster on March 11, 2011.
"They always forget about the volcanoes," he said. "The government has never included Mt. Fuji in its earthquake scenarios."
Fujii's job is to change that. More than a year after the earthquake, tsunami and nuclear power plant meltdown that scarred a generation of Japanese, the government is still working to close the gaps in its disaster response.
Scientists say that the 2011 earthquake may have increased the chances of Mount Fuji erupting. The disaster caused a series of tremors around the mountain, including a magnitude 6.4 quake directly beneath it that caused a 20 meter-long crack in its side and put pressure on the volcano's magma chamber.
The volcano is active and if an eruption was to occur it would potentially threaten a vast area including Tokyo, 100 km (62 miles) away.
Still, Japan's tallest point at 3,776 meters (12,388 feet) and a national symbol that adorns Japanese passports has been silent since 1707.
"Although there are no signs of any irregularities at present, we need to watch it very carefully for another two or three years," said Eisuke Fujita, a senior volcano researcher at the National Research Institute for Earth Science and Disaster Prevention.
Fujita said there have been many examples of volcanoes erupting following a magnitude 9 earthquake, as in Kamchatka, Chile and Sumatra.
"The government has to prepare for a logistical nightmare," he said. "They've said they are going to do something but they haven't got their act together so far."
Part of the problem is the fractured nature of Japanese bureaucracy, with a division between the teams planning for earthquakes and eruptions.
"We don't include an eruption at Mt. Fuji in our earthquake scenarios because we simply don't know whether a quake would cause one or not," a Cabinet office spokesman told Reuters.
The Cabinet in August set up a task force to draft a disaster response plan based on a hazard map drawn up in 2004.
The map shows the areas likely to be affected by lava flows or an ash cloud and it sets priorities for evacuating the surrounding population.
Fujii, who heads the committee and is both a professor emeritus at Tokyo University and executive director of the Crisis and Environment Management Policy Institute, said the government had so far failed to set up sufficient defenses against even its own worst-case scenario.
Under that scenario, the 2004 map suggests economic damage from an eruption would be 2.5 trillion yen ($32 billion).
But it could be "several times" that, Fujii said.
Shizuoka, a prefecture that borders the mountain, will include for the first time an eruption as part of a revised earthquake contingency plan due to be published next June.
Local communities most at risk have been reluctant to discuss such a scenario in the past, concerned it would impact tourism.
A book published in 1983 wrongfully warning of an imminent eruption was blamed for driving tourists away and causing a $3 million loss in revenues for a prefecture bordering the volcano.
The government and Tokyo Electric Power Co Inc, the operator of the Fukushima power plant where the nuclear meltdown happened, described the March 11 disaster as "unforeseeable," despite historical evidence to the contrary.
Critics of the Mount Fuji hazard map say it has omitted several potential consequences of an eruption, ignoring past events.
This includes a partial collapse of the mountain, which could trigger a landslide and an enormous tsunami along Japan's south coast, Masaki Takahashi, professor of geology and volcanology at Nihon University, said.
"Most volcanoes only have one partial collapse in their lifetime, but Fuji has already had two in 20,000 years, meaning it cannot be ruled out as a possibility in the future."
(Editing by Tomasz Janowski and Neil Fullick)