Tianmo Gully is situated along the Yigong Tsangpo–Parlung Tsangpo Deep Fault Zone and constitutes a tributary on the right bank of the Parlung Tsangpo River. The catchment covers an area of approximately 40 square kilometers, with a main gully length of 4 km and an average channel gradient of 244‰. The elevation at the gully mouth stands at 2,460 meters, while the highest peak reaches 5,560 meters, creating a relative elevation difference of 3,100 meters. Modern glaciers have developed above an altitude of 3,800 meters in the upper reaches of the gully, covering roughly 30 square kilometers. The steep terrain and well-developed modern glaciers within Tianmo Gully create favorable conditions for debris flow initiation. Meanwhile, sustained temperature rise accelerates glacial meltwater runoff, generating abundant moraine deposits, rockfall-ice-snow materials and residual deposits in the catchment, which serve as ample loose solid sources for debris flow activities. Seven large-scale debris flow events occurred in Tianmo Gully between 2007 and 2018. From September 5 to 8, 2010, a severe debris flow broke out in Tianmo Gully, blocking the Sichuan-Tibet Highway for 16 consecutive days and causing direct economic losses exceeding 19.7 million RMB.
In April 2020, the Institute of Mountain Hazards and Environment, Chinese Academy of Sciences & Ministry of Water Resources, and the Sichuan Earthquake Administration signed a cooperation agreement to implement seismic monitoring of debris flows in Tianmo Gully, Nyingchi, Xizang. On May 14, 2020, Dai Shigui, Deputy Director of the Institute of Disaster Reduction and Rescue, Sichuan Earthquake Administration, led a team including Senior Engineer Wang Yuwei, Deputy Director of the Mountain Seismic Hazard Research Office, to Bomê County for the installation and commissioning of seismic ground motion monitoring network equipment in Tianmo Gully. After six days of long-distance travel and three days of field operation, the installation and commissioning of the Tianmo Gully seismic monitoring system were completed. The monitoring system consists of three broadband seismic monitoring stations deployed at the gully mouth, the middle reach and beneath the glacier of Tianmo Gully. Monitoring data are transmitted in real time to the Sichuan Engineering Seismic Network Center. Operating around the clock, the system monitors debris flow activities and issues event early warnings, providing valuable observational data for landslide dynamics research and hazard assessment.
Overcoming harsh natural conditions including plateau hypoxia, hiking across landslide masses, working in the rain and insect harassment, the technical team from the Institute of Disaster Reduction and Rescue successfully completed the installation and commissioning of the seismic monitoring network. The team demonstrated the dedication of staff from the Sichuan Earthquake Administration. This work has won high recognition from the Institute of Mountain Hazards and Environment, CAS & MWR, laying a solid foundation for long-term cooperation between the two institutions.
(Source: Sichuan Earthquake Administration)