Tips about the Changbai Mountain

Jianguang Zhang 2020-10-19 22:49:36

In 2020, Prof. Dr. Pujun Wang et al published a popular science article in the journal of Acta Petrologica Sinica: Characteristic and source-sink response of the Lahar deposits in Changbaishan-Tianchi volcano and adjacent area following the Millennium Eruption. The article includes some questions which draw the attention of the public, so that they are shared here.

1. It is rumoured that the Tianchi Lake, the crater of the Changbai Volcanic Mountain, only has water that goes out, but there is no water that comes in. Is it right?
The answer is No, because it does not comply with the principle of conservation of mass.

2. It is rumoured that the Tianchi Lake is always full of water. Is it right?
The answer is No, because it does not comply with Darcy\'s law of percolation. According to the principle of conservation of mass and Darcy’s law, the results of mathematical simulation of the accumulation conditions, and water collection process of the Tianchi Lake, when the overall permeability of the volcano is higher than a certain value (4-6 milli-darcy), the Tianchi Lake will be a leaky basin which makes it impossible to collect water. Therefore, when each large-scale eruption of the volcano leads to the development of the fissure system and the overall permeability of the volcano is at a high level, water in the Tianchi Lake will leak quickly, and it will take at least 200 years for the water to refill each time thereafter.

3. It is rumoured that the catastrophic volcanic debris flow in Changbai Mountain can only happen when the volcano erupts. Is it right?
The answer is No, because through the source-sink comparison of sediments, it has been found that since 950 AD, there have been more than ten volcanic debris flow events in the Tianchi Lake and adjacent areas of Changbai Mountain, most of which were formed after the eruption period.