Researchers have uncovered the details of a catastrophic volcanic eruption that occurred over 1,000 years ago, leading to a massive flood that reshaped the landscape. The 946 CE eruption of the Changbaishan-Tianchi volcano, located on the China-North Korea border, released vast amounts of magma and triggered a devastating flood that left lasting evidence in the form of boulders and rocks. This discovery sheds light on the potential risks posed by this active volcano and the importance of understanding ancient natural disasters to prepare for future threats. Changbaishan and volcanic eruptions are key topics in this story.
Revisiting The Flood of Catastrophic Nature
In 946 a.d., the Changbaishan-Tianchi/Baekdu volcano displayed its fury, unleashing tens of cubic kilometers of magma from deep within the crust. The eruption then caused a huge flow of water from the lake at the top of the volcano — Heaven Lake. Their analysis of layered deposits following the flood at Grímsvötn was led by Shengwu Qin.
The researchers found that as much as 1 cubic kilometer of water gushed out from the caldera, eroding sediment up to about 34 meters per hour for approximately three hours. Evidence of this flood persists today in the ample boulders and smaller rocks that were scoured from higher up the mountain, and then transported a few hundred metres down to where we now stood. In addition the geologists determined that there were two phases of the eruption with the deluge taking place between them.
The Flood — Investigating the Mechanics
It also contradicted many previous theories about the dynamics of the flooding event, which were published in Water Resources Research. According to Live Science, other scientists proposed that the flood was just one huge deluge emanating from a single blow when the eruption cracked the volcano’s rim. But the authors of this study said they thought that was unlikely because the sediment wasn’t scattered as widely enough to have formed simply from a sudden rush.
Instead, researchers offer three other possible ways the deluge may have played out. In the first, the water spilled from one side of the basin in response to magma rising beneath it. Previously, the volcano triggered an earthquake which resulted in the inner wall of the caldera collapsing into the lake and its over-flooding. The second filled the caldera to its brim with rainfall preceding the event, and weakened part of the south crater rim to allow for overflow.
Protecting Against Future Natural Disasters
But exploring ancient floods like those of 946 CE at Changbaishan-Tianchi may help other susceptible populations gear up for future natural disasters across the globe – not just at this volcano but elsewhere, too. So, while the current activity of Changbaishan-Tianchi may give some volcanologists a jump-start into looking at its risks for local human populations …
The results of this study could be used to improve disaster preparedness and implement risk mitigation strategies. By understanding what caused the catastrophic flood, researchers can identify trends in these types of natural disasters and hopefully protect lives and reduce the impact of a similar event down the road.
