At 1:23 a.m. on April 27, 1986, the Chernobyl nuclear power plant blew up. The world's worst nuclear disaster to date, it left 30 people dead and created a time capsule-like ghost town in Ukraine that is only now beginning to be re-opened to the public.

There are striking differences between that explosion, and the current calamities taking place at Japan's Fukushima Dai-ichi nuclear plant after a magnitude-9 earthquake and tsunami rocked the island nation last week.

While the Japanese disaster is the result of the quake and the tsunami it triggered, Chernobyl happened at the hands of humans.

And the tragic results of the Ukraine explosion were likely worsened by the then-Communist government's lack of transparency, safety standards or emergency management plans, according to David E. Hoffman, author of "The Dead Hand," a book that chronicles the disaster.

The No. 4 reactor at Chernobyl had no containment shell around the reactor itself, and when it exploded it immediately began to spew radioactive debris into the air.

Some of the radioactive debris fell in the immediate area, but a cloud also formed and elements were detected as far away as Sweden.

The Chernobyl explosion also sparked a fire that sent poisonous smoke into the air for 10 days.

It was the heroic firefighters who battled the blaze who suffered most of the casualties. Twenty-eight died within a few weeks from acute radiation poisoning. Two plant workers were also killed and more than 100 people who took part in the cleanup were later confirmed to have acute radiation syndrome.

There has also been a reported increase in childhood thyroid cancer since the incident.

Many of the problems around Chernobyl were a direct result of the Soviet government's poor communication skills, both internally and externally, said Victor Malarek, senior reporter with CTV's W5.

He covered the disaster in 1986 as The Globe and Mail's environment reporter.

"It was a very scary time. You think of all the people back in the Soviet days who were scrambling to get any information they possibly could, but there was a secretive lid (on the disaster). People were exposed to huge amounts of radiation and no one was telling them anything," Malarek told CTV's Canada AM.

It was only 36 hours after the blast that residents of the nearby town of Pripyat began to be evacuated. It was more than a week after the blast, on May 5, that a wider evacuation began, displacing 116,000 people.

The radioactive material that fell contaminated soil, and therefore plants and animals, causing repercussions that were felt for decades.

Moscow was even slower in acknowledging the problem to the outside world, Malarek said.

"It was only when radiation started to fall on Sweden that the alarm bells went off and people said, 'Hey, something has happened, where has it happened?' And they brought it all the way back to this small town in Ukraine and said there's something catastrophic there," he said.

It took two-and-a-half weeks for Soviet Leader Mikhail Gorbachev to go public, appearing on television to make an address about the situation.

The Japanese disaster is currently considered a "serious incident" and has been rated a 6 on the International Nuclear and Radiological Event Scale.

Chernobyl is rated as a 7 on the scale, which qualifies it as a "major incident." Three Mile Island is considered a 5, as an "accident with wider consequences."

Ihor Ostash, Ukraine's ambassador to Canada, lived in Kiev, just 100 kilometres from Chernobyl, when the disaster occurred.

He told Canada AM he remembers being forced to seal doors and windows, and at least twice a day wash everything down with soap and water.

"It was really an invisible threat, an invisible challenge and it was the first time of course and the difference is that at that time the Communist government hid the information from the people and it was a time when we lived with rumours," Ostash said.

"It was really not a pleasant experience for me."

Ostash said his country feels a sense of solidarity with Japan, having been through a similar calamity, and is sending a team to help out in any way possible.

Chernobyl is considered the worst nuclear disaster ever, followed by Three Mile Island in Pennsylvania, and now Japan's crisis. The Three Mile Island facility, like Japan's, had a containment unit and even though a large portion of the reactor melted, there was very little radiation leakage and no casualties.

The containment shell, so effective at Three Mile Island, so far seems to be holding at the Fukushima Dai-ichi plant.

And Japan appears to have learned from Chernobyl's mistakes. So far 180,000 people have been evacuated, the government has been communicating with the public on a daily basis, and emergency measures are in full effect.

But there's still room for improvement for the Japanese government, which is often seen as less than transparent by the public. As Hoffman wrote in a piece for NPR's website, the most important lesson Gorbachev learned from Chernobyl was about the value of "glasnost," or openness, and the risks of deceiving the public during a time of crisis.

"No matter what happens in Japan, being open about it is a huge gain, still, a quarter century later," Hoffman wrote.