Nan Mountain Collapse Expands, Threatening School Buildings

A mountain slope in Tha Wang Pha district, Nan province, Thailand, has experienced a significant expansion of collapse during the rainy season, growing from approximately 2 meters last year to over 100 meters. This escalation has raised safety concerns for Ban Doi Tiew School and nearby residences. Officials from the Nan Provincial Office of Natural Resources and Environment, accompanied by geologists and local agency representatives, inspected the site in Ban Doi Tiew, Si Phum subdistrict, following reports of continuous ground movement. The inspection revealed extensive subsidence and multiple landslide scars around the school, situated at an elevation of about 1,116 meters above sea level. Cracks and fractures were also observed in school buildings, a multipurpose facility, and other structures, indicating ground movement. Local residents reported the initial landslide in the area occurred between May and July 2025, with the affected section being about 2 meters wide. However, this year's rainy season saw the collapse expand to over 100 meters, with additional cracks and fissures appearing across the terrain. Geological surveys identified the site's underlying rock as reddish-brown siltstone and shale, characterized by a high degree of weathering and a thick layer of clay-rich soil covering the slope. These geological conditions increase the potential for further ground movement and landslides, especially during periods of heavy rainfall. The Department of Mineral Resources had previously classified the area as having a moderate to very high risk of landslides. Following the inspection, the Office of Mineral Resources Region 1 prepared a report detailing its findings and recommendations, which has been submitted to the Nan Provincial Office of Natural Resources and Environment. Authorities are continuing to assess the unstable area, with particular focus on the expanding ground collapse and damage to structures at Ban Doi Tiew School. Information source: Pattaya Mail