A supervolcano is a large volcano that has had an eruption with a Volcanic Explosive Index (VEI) of eight, the highest value recorded on the index. This means that the volume of deposits for that eruption is greater than 1,000 cubic kilometers, enough to erase entire cities from the map and cause a global catastrophe of the consequent effects, such as a nuclear winter. Hong Kong’s geology is dominated by igneous rocks, including granitic rocks and volcanic rocks, formed during a major period of volcanic eruption in the Mesozoic era, and researchers say the city’s origins date back to lava and ash. they remain after an eruption of the supervolcano 140 million years ago in the area.
The discovery was made by geologists during the course of their daily study, as they discovered that the rocks they were looking at could be linked to a single source, making the discovery the first of its kind in the region.
The geotechnical engineer from the Department of Civil Engineering and Development, Denise Tang Lai-kwan, said in 2012: “It is correct to say that the main city is located on a very old volcano.
“Although most of the remains are submerged, the granite at Kowloon and the rock pillars on the Ninepin Islands date back to this single source.”
His colleague, Dr. Roderick Sewell, recalled the moment when he realized he was doing something great: the explanation of the city’s unique landscape.
He said, “The ‘ah-ha’ moment for me was realizing that everything pointed to a source, a supervolcano, the only system that could have preserved all of Hong Kong’s unique geological features.
“We are seeing something much bigger than we thought.
“There are only around 50 supervolcanoes in the history of humanity.
“We suspect that more will be added to the list after our discovery.”
The team then mapped out their entire system, from eastern Sai Kung to Kowloon and Hong Kong Island itself, made up of the lava and ash left behind, and called it the ‘High Island Supervolcano’ after Sai Kung Island, which marks the top of the volcano. edge.
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Dr. Sewell added: “The tilt of the system made a lot of difference.
“Erosion and weathering present a cross section of the caldera that gives geologists a window into the anatomy of a volcano in exquisite detail.”
Fortunately, however, there is no reason to fear, as experts said the volcano is now extinct and does not pose a threat to Hong Kong.
But when it last exploded 140 million years ago, it would have darkened the sky with 312 cubic miles of ash, enough to cover the entire region, most likely eliminating any form of life and wreaking havoc in subsequent years.
