In 946 CE, a powerful volcanic eruption occurred at Changbaishan-Tianchi, a volcano located on the border between China and North Korea.
Known as Baekdu in Korean, this volcano released a massive amount of magma and triggered a devastating flood from the lake at its summit, which is now called Heaven Lake.
The eruption sent large boulders and smaller rocks tumbling down the mountain, evidence of which can still be seen today.
Changbaishan-Tianchi is still an active volcano, and scientists are studying it to understand the risks it poses in case of another eruption.
To learn more about the catastrophic flood that followed the 946 eruption, a research team led by Qin investigated the deposits of rock and sediment left behind.
Their findings, published in Water Resources Research, suggest that at least 1 cubic kilometer of water spilled out from the lake on top of the volcano.
This caused intense erosion, with the ground wearing away at rates as high as 34 meters per hour over a period of about three hours.
The study also revealed that the eruption took place in two phases, with the flood happening between them.
Some scientists had previously thought that the flood occurred as one sudden burst after the eruption cracked the rim of the volcano’s crater.
However, Qin’s team found this idea unlikely because the spread of sediment wasn’t as wide as it would have been in such a scenario.
Instead, the researchers proposed three other possibilities for how the flood might have happened.
In the first, magma rising up from inside the volcano could have caused the water to overflow the edge of the caldera. In the second scenario, the eruption could have triggered an earthquake that caused part of the caldera wall to collapse into the lake, which would have forced the water to overflow.
The third possibility is that heavy rainfall before the eruption could have filled the caldera to its limit, weakening the crater rim and allowing the water to spill out.
Studying ancient events like the 946 CE eruption and flood can help scientists understand the dangers of similar future events. By learning more about past volcanic floods, researchers hope to better prepare communities near volcanoes for potential natural disasters.
This research not only applies to Changbaishan-Tianchi but also to other active volcanoes around the world, helping to protect vulnerable populations from future eruptions and floods.
Source: American Geophysical Union.
