The haphazard history that gave Hong Kong some of the most valuable real estate in the world has just got more random.
Geologists say that it sits in the caldera of a supervolcano and is only there thanks to an extraordinary volcanic eruption.
It was one of only about 50 supervolcanoes to have erupted since man walked the planet, none of which have occurred in recorded history.
And now, 140 million years after the event, its existence has been unveiled by geologists who realised what they were looking at during the course of their daily survey work.
“It is correct to say that the main city sits on a very old volcano,” Denise Tang Lai-kwan, Civil Engineering and Development Department geotechnical engineer said.
“Though most of the remnants are submerged, the granite in Kowloon and the rock pillars in Ninepin Islands can be traced back to this one source.“
Her colleague, Dr Roderick Sewell, added: “There are only around 50 supervolcanoes in the history of mankind. We suspect more will be added to the list following our discovery.“
The High Island supervolcano in Hong Kong
Geologists have mapped out its entire anatomy running from eastern Sai Kung to Kowloon and Hong Kong Island itself, formed by the lava and ash left behind.
It has been named the High Island Supervolcano after the Sai Kung island, which marks the volcano’s top edge.
The 18-kilometre-wide (11 miles) caldera of the supervolcano was formed as high pressure and heat at the earth’s core caused the surface to collapse.
The deepest part of the supervolcano is in the middle of the city, in Kowloon and Hong Kong Island, where leftover pockets of magma are marked out in the form of granite.
This supervolcano represents the first discovery of its kind in southeastern China. The volcano is now extinct and poses no threat to Hong Kong. Well this is what they always say…
When it last exploded 140 million years ago, the supervolcano would have darkened the sky with 312 cubic miles of ash, enough to blanket all of Hong Kong.