Monitoring equipment deployed in Gyirong as data shows stable conditions

China has deployed around 20 sets of monitoring equipment across the disaster-hit Gyirong area in the Xizang autonomous region, with real-time data showing geological conditions stabilizing, a senior geologist said.

The devices — including debris flow monitors, slope radars and microseismic sensors — were installed by the China Geological Survey and other emergency response teams following last month's ice-rock avalanche that buried parts of the Gyirong border crossing, causing massive casualties on both sides of the border.

Ge Daqing, deputy director of the China Aero Geophysical Survey and Remote Sensing Center for Natural Resources, said the equipment was positioned at key risk points across the disaster zone to monitor slope movement, debris flow channels and ground deformation in real time.

Two additional slope radars were installed on Wednesday near the border crossing after rescue teams cleared access roads, he added.

The devices are positioned to protect workers repairing roads and power lines by issuing early warnings if falling rocks or shallow landslides are detected on the slopes above.

Data collected so far indicates the dynamic processes at the site have entered a relatively stable phase. "Overall, there have been no significant fluctuations or changes," Ge said, adding that the risk of a large-scale secondary disaster is currently assessed as low without external triggers. However, he cautioned that high-risk factors persist due to the complex terrain.

Some minor rockfalls have been observed at the glacier front in the collapse zone, but Ge said these pose no immediate threat.

The monitoring equipment is primarily intended for the emergency response phase. Once a comprehensive risk assessment is completed and no major threats remain, the devices may be withdrawn, he said.

Beyond the immediate response, the disaster has underscored the limitations of existing monitoring technologies in the high-altitude, cloud-prone Himalayan region.

Ge said optical satellite imagery — the most common remote sensing tool — is severely hampered by persistent cloud cover and fog in the area. Clear images can be obtained on only about 20 days a year, and most of the optical data received recently have been obscured by clouds.

To address this, Ge called for the accelerated development of new synthetic aperture radar satellites, particularly an interferometric SAR satellite constellation that combines L-band, high-resolution, wide-swath capabilities, and both sun-synchronous and low-inclination orbits. This can overcome the challenge of monitoring rapid deformation in the high-elevation mountains and glaciers of the Himalayas.

He also stressed the need to improve satellite revisit cycles and spatial resolution to enable more frequent and rapid monitoring.

Unmanned aerial vehicles offer another monitoring option, but current drones struggle to operate above 7,000 meters and their sensors remain vulnerable to cloud interference. New radar-based sensors and improved high-altitude flight capabilities are needed, he added.

Looking ahead, Ge warned that the risk of high-altitude ice-rock avalanches in the region is likely to increase.

"The 2015 Nepal earthquake caused internal damage to these mountain masses," he said.

"Combined with glacial erosion at high elevations and steep terrain, the structural integrity of rock formations has been compromised, making them prone to collapse."

Given the transboundary nature of such hazards, Ge highlighted the importance of international collaboration in disaster monitoring and early warning across the Himalayan region, noting that ice-rock avalanches and glacial lake outburst floods do not respect national borders.

limenghan@chinadaily.com.cn