Japan will honour nearly 20,000 victims of a massive earthquake and tsunami that struck Japan 10 years ago, destroying towns and triggering nuclear meltdowns in Fukushima, the world’s worst nuclear disaster since Chernobyl.

Emperor Naruhito and Prime Minister Yoshihide Suga will mourn the dead at a commemorative anniversary ceremony in Tokyo on Thursday, while several other events were planned across north-eastern Japan, which was most badly hit by the tremor.

An onslaught of waves triggered by the 9.0-magnitude quake – one of the strongest on record – crashed into the north-eastern coast, crippling the Fukushima Daiichi nuclear power plant. More than 160,000 residents fled as radiation spewed into the air.

The government has spent about 32.1 trillion yen ($A390 billion) to rebuild the tsunami-devastated Tohoku region, but areas around the Fukushima plant remain off-limits over lingering radiation fears. Decommissioning of the crippled plant will take decades and billions of dollars.

The disaster has also left survivors in Tohoku struggling to overcome the grief of losing families and whole communities to the waves in a few frightening hours on the afternoon of March 11, 2011.

Japan is again debating the role of nuclear power in its energy mix as the resource-poor country aims to achieve net carbon neutrality by 2050 to fight global warming. But an NHK public TV survey showed 85 per cent of the public worries about nuclear accidents.

An abandoned house at Okuma, inside the Fukushima exclusion zone. Photo: Getty

The mass demonstrations against nuclear power seen after the tsunami have faded, but distrust lingers. Some anti-nuclear activists are planning demonstrations in front of the operator of the plant, Tokyo Electric Power, for Thursday night.

Only nine of Japan’s 33 remaining commercial reactors have been approved for restarts under post-Fukushima safety standards and only four are operating, compared with 54 before the disaster.

Nuclear power supplied just 6 per cent of Japan’s energy needs in the first half of 2020 compared with 23.1 per cent for renewable sources.