Nagasaki marks 73 years since atomic bombing

A memorial service was held in the city of Nagasaki where the bomb was dropped, just 3 days after the first one leveled Hiroshima. For the first time a United Nations Secretary-General took part in the Nagasaki ceremony.

The city's Peace Park fell silent at 11:02 AM -- the exact moment the bomb exploded in 1945.

More than 70,000 people died in that year alone, and many others from long-term effects. 3,511 survivors passed away in the last 12 months, including a leading advocate for nuclear disarmament.

Among the thousands in attendance were dignitaries of more than 70 countries. UN Secretary-General Antonio Guterres also joined.

The average age of the remaining survivors, known as hibakusha, is now over 82.

An atomic bomb survivor, Terumi Tanaka said, "To this day, I cannot erase from my memory the horrifying scene I witnessed in the Urakami area that day. In a matter of seconds, the atomic bomb indiscriminately stole many lives and injured a great number of people. It will continue to haunt the hibakusha until the day they die. Of all the things humans can do to one another, this is one that can never be forgiven or tolerated."

Tanaka was 13 at the time of the blast and lost 5 relatives on that day. He led a national group of bombing survivors for nearly 2 decades and has dedicated his life to telling his story to people around the world.

The anniversary comes as the Treaty on the Prohibition of Nuclear Weapons was adopted at the UN last year.

Nuclear powers such as the US and Russia didn't support the adoption and have not signed it. Japan which is protected by America's nuclear umbrella also has not signed it. For the treaty to come into force, 50 countries need to ratify it, but so far only 14 have.

The mayor of Nagasaki made an appeal to nuclear powers and countries that depend on their protection -- he then specifically called on the Japanese government.