Tibetannet

A firefighter checks a search dog helping to find the missing after a massive landslide in Xinmo Village in Maoxian County, Tibetan and Qiang Autonomous Prefecture of Aba, Southwest China's Sichuan Province, June 24, 2017. (Photo: China News Service/An Yuan)

Technological advances over the past decade have helped make China's disaster rescue more sophisticated.

This was demonstrated recently after landslides hit a valley in the southwestern province of Sichuan, and rescue workers were warned of risks.

>> Latest on Sichuan Landslide: 

Another 20 taken off missing people's list in China landslide

Secondary landslides hamper rescue efforts

As rescuers were combing through the debris Monday during the search for 93 missing people, they were ordered to leave the site as a slope stability radar sensed secondary slides.

The following day, another landslide hit.

"These new gadgets help us a lot and enable us to better plan the rescue," one rescuer said.

Yang Xiaolin, a senior engineer with China Academy of Safety Science and Technology, said the synthetic aperture radar can detect tiny changes to predict slides.

A drone was also flown over the landslide site that captured data to compile a 3D topographic map. The map was then used to reveal the location of collapsed houses and the depth at which they were buried, rescuers say.

Yan Buqing, an army rescuer, said drones made rescues much more efficient, as they helped narrow down the search area. Life detectors, although a common piece of equipment the world over, sometimes struggle to pick up signals when people are buried deep down, he said.

Rescue teams are typically formed by local army corps, police, fire departments, and red cross branches. The local government directs the operation.

The teams in Sichuan are very experienced as the province seems to suffer more than its share of catastrophes.

In May 2008, a 8.0-magnitude earthquake struck Wenchuan and killed more than 80,000 people. In 2013, another quake hit Lushan, killing 196.

Past rescues have taught the authorities to clear road blocks and restore power and telecommunication as a priority in rescue, said Yan Yudong, head of the civilian Yong'an Rescue Team.

"With roads, goods, power, and telecommunication in place, we can operate with higher efficiency," Yan said.

Despite the improvements, the landslide this month saw eight million cubic meters of rocks and mud accumulating up to 30 meters high, exhausting oxygen beneath the debris, rescuers say.

The 72-hour "golden window" for survival ended Tuesday.

The authorities, however, have not announced the end of the rescue.

Sichuan is situated close to the eastern borders of Qinghai-Tibet Plateau. Earthquakes are frequent making the rocks and earth of the area's mountain slopes very dangerous.

The town proper of Maoxian is built atop ancient landslide ruins. The area was hit by a major earthquake in 1933. Geologists say Maoxian has as many as 900 high-risk areas.

Despite the dangers, people still want to live in the lush valleys like the one hit by landslide, where it is not only beautiful but is easier to grow crops.

>> What lessons can be learned after disaster?

Geologists are working on a warning system that can predict landslides.

In May, signs of a landslide in the province of Gansu were detected and a warning was issued about 40 minutes before it occurred. Farmers and herders were evacuated in time.

"We are making progress, but landslides are still hard to predict," said Xu Qiang, a professor with Chengdu University of Technology who is involved in the research.