The suddenness of the eruption of Japan's Mount Ontake volcano is an extremely rare phenomenon which makes it impossible to take precautionary measures, French volcanologist Jacques-Marie Bardintzeff told AFP Sunday.
After 35 years without a major eruption, the 3,067-metre (10,121-foot) volcano in central Japan reawakened on Saturday, spewing a deadly blanket of ash, rocks and steam down slopes popular with hikers.
Bardintzeff, of the Universities of Paris-Sud Orsay and Cergy-Pontoise, said in an interview that such sudden eruptions were rare.
"In general when a volcano becomes actives, certainly after 30 or 40 years (of dormancy) which is short, we normally expect 24 to 72 hours of warning, The magma moves, micro-seismic movement is registered.. there are changes in temperature."
Normally that is enough time to alert people living in the area to evacuate or to ban access to the site in a tourist area, he explained.
However eruptions which occur with only minutes of warning are not unknown.
The Ontake eruption, in which more than 30 people are feared to have died, was not only sudden but was particularly dangerous as there were so many people about on a busy weekend.
The mountain is popular with hikers, particularly in late September when the autumn colours make for dramatic scenery.
"A combination of factors turn this into a catastrophe," said Bardintzeff, adding that there were different explanations for the unexpected eruption.
"The magma could have found a crack which allowed it to rise up in a single stroke. This is very rare."
There is also another feared type of eruption called hydrovolcanic or phreatomagmatic eruptions.
"Often there are pockets of water in volcanoes. When the magma rises and a wave of heat accompanies it. The water can be quickly vaporised, creating high pressure like in a pressure cooker.
"If this pressure is greater than the resistance of the earth above it, all the rocks are pulverised into fragments known as cinder bombs," the volcanologist explained.
This type of eruption is particularly dangerous precisely because of the speed of events, with no real signs of what is about to happen.
Without more sophisticated seismological equipment than is currently available "unfortunately we are helpless," in such cases, Bardintzeff said.
For the time being no hypothesis has been confirmed as the reason behind the sudden Japanese eruption.
Mount Ontake is a classic Japanese volcano, he explained.
"Japan is a land of volcanoes, with a complex geodynamic system. There are many which erupt in turn."
They are usually of an explosive nature and the plumes of ash and smoke 11 kilometres high, seen in the latest case, are reasonably standard, he added.
"What is exceptional is the fact that it was so sudden."
AFP
Mon Sep 29 2014
Such eruptions were rare and Mount Ontake is a classic Japanese volcano. - AFP Photo
Who is Prabowo Subianto, incoming president of Indonesia?
A wealthy ex-general with ties to Indonesia's popular outgoing president and its dictatorial past, looks set to be its next leader.
Iran's supreme leader says Hamas leader's death will not halt 'Axis of Resistance'
The "Axis of Resistance", built up with years of Iranian support, includes Hamas, the Lebanese Hezbollah group, the Houthi movement in Yemen, and various Shi'ite groups in Iraq and Syria.
Putin says Russia willing to seek compromises between Iran and Israel
Russia is ready to help seek compromises between arch-foes Israel and Iran, President Vladimir Putin said on Friday, saying these would be difficult but possible.
What proposals will Russia push at the BRICS summit?
The proposal is also to establish a BRICS reinsurance company to allow uninterrupted shipment of goods and key commodities between members.
Indonesia's free meals plan in the spotlight as Prabowo readies for office
Prabowo calls the programme one of the main drivers of economic growth, eventually set to add an estimated 2.5 million jobs.
Astro AWANI's revamped English news website, AWANI International, launches on Oct 21
Astro AWANI's revamped English platform delivers in-depth global news and expert analysis to keep you informed on key developments.
Israeli strikes kill 33 people in Jabalia refugee camp in Gaza, medics say
Residents of Jabalia said Israeli tanks had reached the heart of the camp after pushing through suburbs and residential districts.
Liam Payne's ex-partner calls for media restraint after 'painful' death
Cheryl Tweedy used her statement to urge the media to remember they had a seven-year-old son, Bear, who could read the reports.
Analysts: Indonesia's strong MoF leadership team to boost investor confidence
Sri Mulyani Indrawati as head of Indonesia's Ministry of Finance is expected to instil confidence among investors.
Biden offers both a carrot and a stick to Israel as his term nears an end
Israel has frequently resisted US advice and has caused political difficulties for the Biden administration.
Putin says BRICS will generate most of global economic growth
Russian President Vladimir Putin will host a summit of the group in the city of Kazan on Oct. 22-24.
ISIS Malaysia's perspective of Budget 2025
An excellent rakyat-centric budget under the overarching principle of a caring and humane economy.
Budget 2025: Record increase in STR, SARA aid initiatives
The government will provide a significant boost to the Sumbangan Tunai Rahmah (STR) and Sumbangan Asas Rahmah (SARA) initiatives next year.
Budget 2025: EPF contributions to be made mandatory for foreign workers – PM Anwar
The government plans to make it compulsory for all non-citizen workers to contribute to the Employees Provident Fund (EPF).
What policies to expect from Indonesia's new President Prabowo
Prabowo will be open to foreign investment, his aide has said, such as by offering investors management of airports and sea ports.
Budget 2025: Govt allocates RM470 mil to empower women's participation in PMKS
The Women's Leadership Apprenticeship Program will be intensified as an effort to produce more female corporate personalities.
Israel sends more troops into north Gaza, deepens raid
Residents of Jabalia in northern Gaza said Israeli tanks had reached the heart of the camp, using heavy air and ground fire.
Indonesia ramps up security ahead of Prabowo's inauguration
Prabowo Subianto will be sworn in as Indonesia's president on Sunday with Vice President-elect, Gibran Rakabuming Raka, also taking office.
Immediate allocation of RM150 mil for local authorities, DID to tackle flash floods
Datuk Seri Anwar Ibrahim said this allocation is intended to address the recent flash floods that hit the capital and several major towns.
Budget 2025: Sabah, Sarawak to continue receiving among highest allocations - PM
Sabah and Sarawak continues to be prioritised under Budget 2025, with allocations of RM6.7 billion and RM5.9 billion respectively.