A 6.2-magnitude earthquake jolted the plateau county of Jishishan in northwest China's Gansu Province at midnight Monday, killing 118 people in Gansu and the neighboring Qinghai Province. 

The earthquake took place in an area on a seismic belt that is very active and prone to large earthquakes in history, according to Professor Ma Changqian from the School of Earth Sciences at the China University of Geosciences.

"The county is located on the north-south seismic belt of China. Historically, large earthquakes occurred frequently here," Ma told CGTN.

"The most well-known quake that has occurred on this belt is the Wenchuan Earthquake on May 12, 2008," he said, referring to the 8.0-magnitude earthquake in southwest China's Sichuan Province, killing nearly 70,000 people and leaving nearly 18,000 missing. "Both quakes are on the same seismic belt but on two different seismic faults."

Ma said that the belt lies between the Eurasian Plate and Indian Plate, two tectonic plates that are pushing against each other, leading to frequent quake activity. He also warned of secondary disasters such as landslides.

According to the International Knowledge Center for Engineering Sciences and Technology under the Auspices of UNESCO, the north-south earthquake belt of China is a dense seismic belt that runs through the Chinese mainland, roughly in the direction of north and south, from northwest China's Ningxia Hui Autonomous Region through eastern Gansu, western Sichuan, until Yunnan Province in southwest China.

Causes behind casualties

Professor Xu Xiwei from the China University of Geosciences believes that there are three reasons why the quake has caused so many casualties: poor earthquake resistance of residents' houses, relatively dense population in the area and less time for residents to respond as the quake shook at midnight when most people are asleep. 

According to the Blue Sky Rescue Team, China's largest non-governmental humanitarian organization, which sent members for rescue missions, casualties in the densely-populated county center area have not been severe, but the destruction to residents' houses in rural areas is more serious.

"It's very different when an earthquake happens in a rural area compared with that in a city. Most houses in a city are reinforced concrete structures, which can stand on the ground for some time when an earthquake happens. In a rural area, however, most houses are made of earth and wood, which could fall quickly during an earthquake. Such circumstances require faster search and rescue, in just a couple of hours," said Yu Ruofei, head of Blue Sky's Gansu division.

Xinhua News Agency reported the damaged houses, roads and other infrastructure. Several villages suffered power failure and water supply disruption. 

Over 2,000 responders have been sent to help with rescue and relief work. 

Blue Sky members said that the low temperatures in the area have become a major challenge for their operation. Local meteorological authorities forecast the daily low temperature in Jishishan is reported to reach minus 10 degrees Celsius on Tuesday.

(Cover: Rescuers carrying out search and rescue mission in Jishishan Bao'an, Dongxiang, Sala Autonomous County in northwest China's Gansu Province, December 19, 2023. /Gansu Forest Fire Brigade)