CUHK-Led Research Finds That Landslide-Dammed Lakes May Trigger Earthquakes

CUHK-Led Research Finds That Landslide-Dammed Lakes May Trigger Earthquakes
A latest study from an international team led by the Earth and Environmental Sciences of the Faculty of Science at CUHK found that landslide-dammed lakes are not only the result of earthquakes, but they may also initiate earthquakes. Adrian Yu/The Epoch Times
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Earthquakes trigger landslides, with the resulting downpour of mud and rocks blocking riverbeds to form landslide-dammed lakes (LDLs). A global study led by the Earth and Environmental Science Research Team of the Faculty of Science at the Chinese University of Hong Kong (CUHK) found that LDLs are not only the result of earthquakes, but they may also cause earthquakes. This is the very first study to conclude that surface hazards and earthquakes have such a mutual cause-and-effect relationship. Researchers believe that this discovery will help implement precise disaster prevention efforts post-earthquakes.

In 2018, two landslides occurred at Baige on the Qinghai-Tibet Plateau. The volume of the cascades from those two incidents totaled 33 million cubic meters (1.17 billion cubic feet), equivalent to 13,000 Olympic-standard swimming pools, and formed LDLs. The CUHK Earth and Environmental Sciences course members later observed that more than 60 earthquakes occurred in the area within a week after the landslide, a frequency 20 times higher than before the formation of the LDLs.

The CUHK team led an international research cohort, comprising the Swiss Federal Institute for Forestry, Snow and Landscape Research, the Chengdu Institute of Mountain Hazards and the Environment of the Ministry of Water Resources of the Chinese Academy of Sciences, and the Seismological Bureau of Sichuan Province. The team analyzed a high-precision earthquake catalog constructed based on artificial intelligence (AI), and established a seismic stress triggering model, confirming that the earthquakes mentioned above are likely to be triggered by the gravity loading and fluid pressure diffusion of the barrier lake.

Increased Water and Pore Pressure Causes Faults to Slip Further Triggering Earthquakes

Assistant Professor Tan Yen-joe of the Earth and Environmental Sciences Program at the Faculty of Science of CUHK, who led the research, said that this study is the first of its kind to confirm that earthquakes can be triggered by natural disasters on the Earth’s crust. He explained that when landslides block river valleys or riverbeds and form LDLs, the rise in water level causes an increase in water pressure, thereby increasing the load on the ground. The lake water will also diffuse into the underground pores and increase the pore pressure. A combination of these two pressure buildups will push the nearby faults to separate and trigger further quakes.

Zhang Zhen, the lead author of the study and a postdoctoral researcher in the Earth and Environmental Sciences Program at the Faculty of Science of CUHK, pointed out that the results of this study are of great significance for future earthquake risk management. For example, he cited the 2008 Wenchuan earthquake in China, which triggered more than 100,000 landslides and formed hundreds of LDLs. They may have been one of the factors responsible for some of the subsequent earthquakes that year. This study confirms that natural disasters at ground level and earthquakes could be the cause and effect of each other and may even develop into a recurring vicious cycle.

Mr. Zhang added that in areas where large-scale landslides frequently occur and LDLs form, such as in seismically active high mountain areas in southwest China and the Himalayas, the chain effects of earthquakes caused by the LDLs may need to be taken into consideration in performing future natural disaster risk assessments. Especially in the aftermath of a large-scale landslide, emergency response departments in relevant areas must prepare for possible aftershocks.

Melting Glaciers May Also Increase Earthquake Frequency

Liu Min, the second author of the study and a postdoctoral researcher in the Earth and Environmental Sciences Program at the Faculty of Science of CUHK, said that the melting of glaciers would also cause the volume and weight of glacial lakes to increase, forming a structure like an LDL, and may then go through similar processes as the mechanism causing earthquakes. In this respect, global warming may increase the frequency of earthquakes in some high-risk areas.

Mr. Tan said that the team will study further in the future whether there were phenomena in other parts of the world exhibiting similar earthquakes caused by the landslide to understand the scale and prevalence of this phenomenon. They will also try to learn more about structures that are similar to LDLs, such as glacial lakes, and their potential links to triggering earthquakes. He added that the huge Baige slope had been moving slowly for decades, and suddenly collapsed in 2018, forcing the evacuation of more than 120,000 people. Therefore, the team hopes to study further the mechanism of the instantaneous collapse of these slow-moving huge slopes to understand whether there are ways to predict sudden landslide disasters.

The research results have been published in the internationally renowned academic journal “Nature Communications.”