Mudflow phenomenon in Phu Yen: Signs of geological fault activity

(Illustrative photo. Source: VNA)

Since April 7-9, in Tan Vinh village (Xuan Son Nam commune, Dong Xuan district, Phu Yen province), there has been a phenomenon of mud overflowing on the ground, flowing into streams and then solidifying, with many long cracks appearing around.

The strange phenomenon attracted the curiosity of local people. Many information about the incident was quickly posted on social networking sites with some unverified information, causing some confusion among the public.

"Decoding" the phenomenon of mudflows

Faced with the above phenomenon, a representative of the Central Region Water Resources Planning and Investigation Federation (National Center for Water Resources Planning and Investigation) said that experts had been sent to the field to survey, measure, and collect relevant information, in order to make assessments of the nature of the phenomenon based on accurate factual bases and scientific arguments.

Dr. Vu Manh Hai - Deputy Head of the Central Region Water Resources Planning and Investigation Federation, said that the location of the self-erupting mud is located at the intersection of the extension direction of the fault systems developing in the Northwest - Southeast direction and the meridian direction.

According to Mr. Hai, the composition of the mud includes quartz gravel fragments which are predicted to be weathering products of intrusive rocks in the area covered by unconformable Quaternary sediments.

“This may give an initial conclusion that the mud is being released due to tectonic activities along the fault extending from high terrains in the neighboring mountainous areas when conditions are favorable for exposure (specifically where the cover above the fault is thin and loses its connection when the soil on the surface dries out),” Mr. Hai analyzed.

The Deputy Head of the Central Region Water Resources Planning and Investigation Federation also said that a similar phenomenon of spontaneous mud eruption at the same location had been recorded nearly 50 years ago, lasting about 10 days before stopping. The cause could be that the mud erupted and then solidified, filling the system of cracks connected to the fault, blocking the paths for the mud to flow out of the ground.

“The result of this spontaneous mud eruption is the formation of the current small hill with the peak at the eruption location a few meters higher than the surrounding area, completely natural, not the result of any human leveling process or other natural phenomenon,” Dr. Vu Manh Hai further explained.

Previously, speaking to the press, Professor Tran Thanh Hai - Principal of the University of Mining and Geology, also said that mud eruption is a geological phenomenon in which a mixture of mud, solution and gas accumulated underground erupts to the surface.

Recent geological research results show that mud eruptions often occur in areas with high pressure gas, active tectonic activities, increased geothermal resources, and areas with underground oil and gas accumulations.

Mudflows can also occur in basins that are buried with young, loose sediments rich in decaying organic matter. In some earthquake-related cases, mudflows may be formed by the liquefaction of loose, clay-rich, water-rich sediments.

No signs of danger

Although the phenomenon of mud overflowing on the ground and flowing into streams, through the results of surveys and practical research, Dr. Vu Manh Hai assessed that the quality of the mud is relatively good in terms of sensory perception, with normal temperature, and has not recorded any harmful risks to the environment and people's health and lives.

However, the representative of the Central Region Water Resources Planning and Investigation Federation also noted that the quality of mud will be specifically assessed after the results of analyzing some important components and comparing with the corresponding components in mineral mud currently used for bathing in the area, especially in Khanh Hoa province.

In addition, accurate conclusions need to be based on other in-depth experiments and surveys conducted on the basis of the observations drawn from this rapid survey. Therefore, the government and relevant agencies need to continue to closely monitor the developments of this phenomenon in the coming time to have appropriate responses when necessary.

According to vietnamplus.vn

Source: https://baodanang.vn/xa-hoi/202504/hien-tuong-bun-trao-o-phu-yen-co-dau-hieu-hoat-dong-cua-cac-dut-gay-dia-chat-4003468/